Power transfer system and methods

Abstract

A system and associated method for transmitting power between a DC source and a variable load. Two power signals are extracted from the DC source at a high frequency via two self-synchronizing radio frequency rectifiers / amplifiers switched by two corresponding high-frequency switching signals, the two corresponding high-frequency switching signals having a phase difference controlled by a duty cycle and overlap controller. The two high-frequency power signals are mixed in a wired, wireless, or dual-peak wireless high-frequency power link system to generate a transmitted power signal based on the mixing and manipulation of the phase difference. An expanded output power signal is formed from the transmitted power signal by a power signal conversion circuit communicating with the high-frequency power link system. This system and method allow an adjustable DC power signal and an AC power signal phase-locked to an existing power signal in the load to be transmitted to the load.

Description

Power transmission system and method The present invention relates to a power transmitter, a receiver, and a system and method for power transmission. In inductive power transfer (IPT), power is typically transferred between coils via a magnetic field. Alternating current (AC) is driven through a transmitter coil, creating an oscillating magnetic field. This magnetic field passes through a receiver coil, where it induces AC in the receiver coil. The induced AC can then drive a load directly or be rectified into direct current (DC), which is then applied to drive a load. To achieve high efficiency, the transmitter and receiver coils must be very close together. For example, the transmitter and receiver coils are typically separated by only a fraction of the coil diameter (e.g., within a few centimeters), and the coil axes are closely aligned. In some IPT systems, resonant inductive coupling is employed. Resonant inductive coupling can improve IPT efficiency by using a resonant circuit. Resonant inductive coupling can achieve higher efficiency over longer distances than non-resonant inductive coupling. In resonant inductive coupling, power is transferred via the magnetic field between two resonant circuits: one in the transmitter and the other in the receiver. Both circuits are tuned to resonate at the same resonant frequency. In some IPT systems, magnetic fields can induce eddy currents in nearby metal. This can lead to significant temperature increases and fire hazards. Ferromagnetic plates can be used to provide shielding and improve inductive coupling, but this can increase the cost of these systems. Capacitive power transfer (CPT) utilizes electric fields to transfer power between two electrodes, such as metal plates. Typically, four metal plates are used in a CPT system to form a capacitive coupler. Two plates act as power transmitters, while the other two act as power receivers, resulting in at least two coupling capacitors that provide a power flow loop. The transmitter applies an AC voltage to the transmitting plate. The oscillating electric field induces an AC potential on the receiver plate, causing AC current to flow in the load circuit. Resonance can also be used with capacitive coupling to extend the power transfer range. In CPT systems, eddy currents can be reduced, and the plates used are low-cost, reducing system costs. However, a problem with many systems is that high voltages can be forced across the plates. These high voltages can generate strong electric fields, which can lead to significant field emissions to the surrounding area. CPT and IPT systems also present challenges associated with capacitive or inductive compensation networks. Currently, both CPT and IPT systems require minimal separation between the receiver and transmitter. This typically requires large capacitors and inductors in the compensation networks on both the primary and secondary sides. Manufacturing these large components is difficult, and their parasitic resistance can significantly reduce system efficiency. Furthermore, these compensation components do not directly participate in the power transfer process. Wireless power transmitters and receivers with fewer components and / or reduced cost are still desirable. Wireless power transmitters and receivers with reduced reliance on compensation networks are still desirable. Wireless power transmitters and receivers with higher efficiency are still desirable. Wireless power transmitters with more flexible requirements regarding alignment and spacing between them are still desirable. There is still a need for power transmission systems capable of transferring power in both forward and reverse directions between a load and a power source, including between a DC source and an AC grid. The field of power transmission in consumer products is becoming increasingly important. In the automotive sector, wiring harnesses have become a critical and expensive subsystem of the vehicle. The automotive wiring harness market is expected to exceed $77 billion this decade. In an era of increasing focus on gas mileage and carbon emissions for internal combustion vehicles, as well as the range of electric vehicles, the cost, weight, and power transmission efficiency of these wiring harnesses have become major concerns in vehicle design. These concerns are understandable, given that materials and components account for 57% of vehicle manufacturing costs. While battery technology has steadily improved to provide higher energy density, consumer demand for an increasing number of auxiliary user electronics and electric drive systems integrated into vehicles has also increased. This has placed increasing demands on battery and vehicle weight, cost, and power transmission efficiency. In the 1990s, the automotive industry advocated for higher voltage battery systems, partly due to the desire to reduce wiring harness weight. There have been many efforts to reduce the amount of expensive copper used in wiring harnesses, and there is a trend towards using cheaper aluminum. This trend is also driven by the desire to save about 40 pounds of weight in a typical car. This trend towards aluminum has its own problems, in part because aluminum has a resistivity 1.58 times that of copper. Aluminum also suffers from a phenomenon called creep, which can cause connections to loosen. In addition, aluminum can oxidize, so precautions must be taken with connections. Some aspects of wiring harnesses still require copper, and any connection between copper and aluminum will introduce problems with current potential. Therefore, there is a clear need for an alternative approach to vehicle wiring harnesses that reduces expensive copper content, provides flexibility in voltage, avoids the problems typified by aluminum, and reduces weight. At the same time, the efficiency of power transmission technology needs to be improved to keep pace with the rapid advancement of battery technology, which is in turn stimulated by developments in the electric vehicle field. For example, these requirements are not limited to the automotive sector but also apply to the field of solar power transmission and, with certain modifications, to other consumer devices in the home, such as computers and television monitors. Power conditioning units that optimally extract power from power sources with varying voltages are widely used today, but these power conditioning units are often subject to limited control facilities. This, in turn, prevents optimization of power transmission efficiency. The above examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of ordinary skill in the art after reading this specification and studying the accompanying drawings. In a first aspect, a dual-peak near-field resonant wireless power transmission system is provided. The dual-peak near-field resonant wireless power transmission system is configured to simultaneously perform capacitive power transmission and inductive power transmission according to an adjustable transmission mode ratio at a resonant power signal oscillation frequency. The system includes: a transmitter subsystem including a transmitter antenna subsystem and a power signal tuner module, the tuner module being configured to adjust the transmission mode ratio by adjusting the power signal provided by the tuner module to the transmitter antenna subsystem; and a receiver subsystem including a receiver antenna subsystem, the receiver antenna subsystem being configured to receive power from the transmitter antenna subsystem according to the transmission mode ratio. The tuner module may be configured to adjust the power signal provided to the transmitter antenna subsystem by adjusting a phase difference between a current and a voltage of the power signal. The transmitter subsystem may further include: a controller; and at least one sensor, wherein the controller is configured to receive sensor information from the at least one sensor and to automatically provide a tuning instruction to the tuner module based on the sensor information; and the tuner module is configured to adjust the phase difference between the current and the voltage of the power signal provided to the transmitter antenna subsystem according to the tuning instruction. The at least one sensor may be disposed on the transmitter subsystem. In other embodiments, the at least one sensor may be disposed on the receiver subsystem, and the controller may be configured to wirelessly receive the sensor information. The at least one sensor may be one of the following: a power load sensor, a transmission power sensor, a surrounding object detector, and a distance detector configured to monitor the distance between the transmitter antenna and the receiver antenna. The resonant power signal oscillation frequency can be freely varied within a predetermined frequency band. The predetermined frequency band can be an Industrial, Scientific, and Medical (ISM) band. The system can be detuned to a degree that allows the resonant power signal oscillation frequency to vary within opposite extremes of the predetermined frequency band. In another aspect, a wireless method for bimodally transmitting power at a resonant power signal oscillation frequency according to an adjustable transmission mode ratio is provided, the method comprising: providing a transmitter subsystem comprising a power signal tuner module and a transmitter antenna subsystem configured to resonate at the resonant power signal oscillation frequency; providing a receiver subsystem comprising a receiver antenna subsystem configured to resonate at the resonant power signal oscillation frequency; providing a power signal from the tuner module to the transmitter antenna subsystem at the resonant power signal oscillation frequency; adjusting the transmission mode ratio by adjusting the power signal from the tuner module to the transmitter antenna subsystem; and receiving the transmitted power at the resonant power signal oscillation frequency via the receiver antenna subsystem at the transmission mode ratio in the receiver subsystem. Adjusting the transmission mode ratio may include adjusting a phase difference between a current and a voltage of the power signal provided to the transmitter antenna subsystem. Providing a transmitter subsystem may further include providing a controller and at least one sensor, wherein the tuner module may adjust the phase difference between the current and voltage based on sensor information received by the controller from the at least one sensor via a command from the controller. Upon receiving the sensor information, the controller may automatically issue the command from the controller to the tuner module; and the tuner module may automatically execute the command from the controller to change the phase difference. The method may further include allowing the resonant power signal oscillation frequency to vary within a predetermined frequency band. The predetermined frequency band may be an Industrial, Scientific, and Medical (ISM) band. Providing a transmitter subsystem may include providing a transmitter subsystem that is detuned to a degree that allows the resonant power signal oscillation frequency to vary within opposite extremes of the predetermined frequency band. In another aspect, a dual-peak near-field resonant wireless power transfer system is provided. The dual-peak near-field resonant wireless power transfer system is configured to simultaneously perform capacitive power transfer and inductive power transfer according to an adjustable transfer mode ratio of capacitive power transfer and inductive power transfer at a variable resonant power signal oscillation frequency. The system includes: a transmitter subsystem including a transmitter antenna subsystem and a power signal tuner module, wherein the power signal tuner module adjusts the transfer mode ratio by adjusting a power signal provided by the power signal tuner module to the transmitter antenna subsystem; and a receiver subsystem including a receiver antenna subsystem, which receives power from the transmitter antenna according to the transfer mode ratio. The system transmits information between the transmitter antenna subsystem and the receiver antenna subsystem via the transmitter antenna and the receiver antenna of the receiver antenna subsystem. The system may further include a modulator for modulating information onto an information-bearing signal and providing the information-bearing signal to the transmitter antenna subsystem. The system may modulate information onto an information-bearing signal and provide the information-bearing signal to the transmitter antenna subsystem. The modulator may be arranged to modulate the information-bearing signal to the transmitter antenna subsystem based on the information. The power signal tuner module may include the modulator. The information-bearing signal may have a frequency different from the oscillation frequency of the variable resonant power signal. The modulator may modulate the information-bearing signal by any of frequency modulation, amplitude modulation, and phase modulation. The information-bearing signal may be modulated such that the oscillation frequency of the variable power signal is a harmonic of the frequency of the information-bearing signal. The information-bearing signal may be modulated onto a harmonic of the power signal. The modulated signal provided to the transmitter antenna subsystem may be the power signal. The modulator can modulate a reflection characteristic of the receiver antenna and transmit the information from the receiver antenna subsystem to the transmitter antenna subsystem by modulating the reflection characteristic of the receiver antenna according to the information. The modulated reflection characteristic of the receiver antenna can be an impedance of the receiver antenna. The system can transmit information from the receiver subsystem to the transmitter subsystem by modulating the reflection of the signal from the transmitter subsystem by the receiver antenna. The receiver subsystem can modulate the reflection characteristics of the receiver antenna. The receiver subsystem can modulate the impedance of the receiver antenna. An electrical load may be present at the output of the receiver subsystem; and the information may include one or more of the presence of the electrical load, the charge level of the electrical load, the power transfer efficiency, the charging rate of the electrical load, the status of the electrical load, the presence of voltage across the electrical load, the charge capacity of the electrical load, and a remaining time to charge the electrical load. The system can transmit digital information between the transmitter subsystem and the receiver subsystem via the transmitter antenna. The system can transmit analog information between the transmitter subsystem and the receiver subsystem via the transmitter antenna. The receiver subsystem can be configured to transmit power to a subsequent receiver subsystem. The receiver can further include a rectifier including a phase shifter. In yet another aspect, a dual-peak resonant near-field RF power transfer system is provided, comprising a plurality of power transmit-receive modules configured to simultaneously perform capacitive power transfer and inductive power transfer at a power signal frequency via a power signal according to an adjustable transfer mode ratio, wherein each of the plurality of power transmit-receive modules is in wired communication with a transmitter-receiver resonator configured to exchange power with at least one other of the plurality of power transmit-receive modules. A first power TRX module among the plurality of power TRX modules may include a power signal tuner module, the power signal tuner module being adjustable for varying the transmit mode ratio by adjusting a power signal provided by the power signal tuner module to a TRX resonator in wired communication with the first power TRX module among the plurality of power TRX modules. At least one of the plurality of power TRX modules may include a modulator configured to modulate information onto a radio frequency signal, the radio frequency signal being exchanged between an associated TRX resonator in wired communication with the at least one power TRX module and a TRX resonator in wired communication with any other of the plurality of power TRX modules. The modulator may be any one of an amplitude modulator, a frequency modulator, and a phase modulator. The information may include one or both of digital information and analog information. The RF signal modulated by the modulator may be a power signal. The RF signal modulated by the modulator may have a frequency different from the power signal frequency. The RF signal modulated by the modulator may have a frequency that is a harmonic of the power signal frequency. The power signal frequency may be a harmonic of the frequency of the modulated signal. The modulator may be arranged to modulate a reflection characteristic of an associated wire-connected transmitter-receiver resonator according to the information to impose the information on a signal reflected by the wire-connected transmitter-receiver resonator. The modulator may be arranged to modulate a signal provided to the associated transmitter-receiver resonator according to the information. The power signal tuner module of the first power transmit-receive module of the plurality of power transmit-receive modules may include the modulator. Each of the power transmit-receive modules may include a compensation network, and the compensation network may include the modulator. At least one of the power transmit-receive modules may include a radio frequency oscillator that provides a signal to the at least one power transmit-receive module at the power signal frequency, and the radio frequency oscillator may include the modulator. Each of the plurality of power transmit-receive modules can be reconfigured between a power transmitter mode and a power receiver mode. Each of the power transmit-receive modules can include a differential self-synchronous RF power amplifier / rectifier, which can be reconfigured between an amplifier state and a rectifier state corresponding to the power transmitter mode and the power receiver mode of the power transmit-receive module, respectively. The differential self-synchronous RF power amplifier / rectifier can be a differential switching mode self-synchronous RF power amplifier / rectifier. Each of the power transmit-receive modules can include a controller, and the reconfiguration can be controlled by the controller. Each differential self-synchronous RF power amplifier / rectifier can include a phase shifter, which can be adjusted by the controller to reconfigure the differential self-synchronous RF power amplifier / rectifier between the amplifier state and the rectifier state. When a power load is present at the output of one of the plurality of power transmit-receive modules in receiver mode, the information may include one or more of the presence of the power load, the charge level of the power load, the power transfer efficiency, the charging rate of the power load, the status of the power load, the presence of voltage across the power load, the charge capacity of the power load, and the remaining time to charge the power load. In yet another aspect, a near-field radio frequency (RF) method for transferring power via a power signal at a power signal frequency is provided. The method includes providing a dual-peak resonant near-field RF power transfer system comprising a plurality of power transmit-receive modules, wherein each of the plurality of power transmit-receive modules is in wired communication with a transmitter-receiver resonator configured to exchange power with at least one other of the plurality of power transmit-receive modules; and operating the power transfer system for simultaneous capacitive power transfer and inductive power transfer according to an adjustable transfer mode ratio. A first power transmit-receive module among the plurality of power transmit-receive modules provided may include a power signal tuner module; and operating the power transfer system may include changing the transmit mode ratio by adjusting the power signal tuner module. Providing the power transfer system may include providing at least one power transmit-receive module among the plurality of power transmit-receive modules that is in wired communication with an associated transmitter-receiver resonator and has a modulator; and operating the power transfer system may include exchanging radio frequency signals between the associated transmitter-receiver resonator and a transmitter-receiver resonator in wired communication with at least another one of the plurality of power transmit-receive modules; and modulating information onto the exchanged radio frequency signals. When a power load is present at the output of one of the plurality of power transmit-receive modules, the information may include, for example, without limitation, one or more of the presence of the power load, the charge level of the power load, the power transfer efficiency, the charging rate of the power load, the status of the power load, the presence of voltage across the power load, the charge capacity of the power load, and the remaining time to charge the power load. The information may be modulated onto the exchanged radio frequency signal by amplitude modulation, frequency modulation, or phase modulation. Modulating the information onto the exchanged radio frequency signal may include modulating digital information or analog information onto the exchanged radio frequency signal. Modulating the information onto the exchanged radio frequency signal may include modulating the information onto the power signal. Modulating the information onto the exchanged radio frequency signal may include modulating the information onto a signal having a frequency different from the power signal frequency. Modulating the information onto the exchanged radio frequency signal may include modulating the information onto a signal having a frequency that is a harmonic of the power signal frequency. Modulating the information onto the exchanged radio frequency signal may include modulating the information onto a signal having the power signal frequency as a harmonic. Modulating the information onto the exchanged radio frequency signal may include modulating a reflection characteristic of the associated wired transmitter-receiver resonator according to the information to impose the information on a signal reflected by the wired transmitter-receiver resonator. Modulating the information onto the exchanged radio frequency signal may include modulating a signal provided to the associated transmitter-receiver resonator according to the information. The method may include operating the power signal tuner module of the first power transmit-receive module of the plurality of power transmit-receive modules to modulate the information onto the exchanged RF signal. Each of the provided power transmit-receive modules may include a compensation network, and the compensation network may include the modulator, allowing the compensation network to be operated to modulate the information onto the exchanged RF signal. At least one of the power transmit-receive modules may include a RF oscillator that provides a signal at the power signal frequency to the at least one power transmit-receive module, and the RF oscillator may include the modulator, allowing the information to be modulated in the oscillator onto the exchanged RF signal. Each of the plurality of power transmit-receive modules provided is reconfigurable between a power transmitter mode and a power receiver mode; and the method may further include reconfiguring at least two of the plurality of power transmit-receive modules between the power transmitter mode and the power receiver mode to reverse the direction of power transmission between the at least two transmit-receive modules. Each of the power transmit-receive modules provided may include a differential self-synchronous RF power amplifier / rectifier capable of reconfiguring between an amplifier state and a rectifier state corresponding to the power transmitter mode and the power receiver mode of the power transmit-receive module, respectively; and the method may include reconfiguring the differential self-synchronous RF power amplifier / rectifier of the at least two transmit-receive modules between the amplifier state and the rectifier state. Each differential self-synchronous RF power amplifier / rectifier may include a phase shifter that is adjustable for reconfiguring the differential self-synchronous RF power amplifier / rectifier between the amplifier state and the rectifier state; and the method may include adjusting the phase shifter of each of the differential self-synchronous RF power amplifiers / rectifiers in the at least two transmit-receive modules. In yet another aspect, a near-field resonant wireless power transfer system is provided, comprising: a transmitter subsystem including a plurality of substantially mutually decoupled transmitter resonators, and a corresponding transmitter module in power signal communication with each transmitter resonator, each transmitter module including a transmit controller and a power signal source having a power signal oscillation frequency and a power signal phase, each power signal source being controlled by the corresponding transmit controller; one or more receiver subsystems, each including a corresponding receiver resonator; a software lookup table having discrete allowed power signal oscillation frequencies for the power signal sources; and software that, when loaded into memory and executed by a controller of any of the transmitter modules, performs the following actions: measuring one of an input impedance of the corresponding transmitter resonator and a test signal power draw of the corresponding transmitter resonator; and selecting a frequency for the corresponding power signal source from the lookup table based on one of the input impedance of the corresponding transmitter resonator and the test signal power draw of the corresponding transmitter resonator. The software, when executed, can measure power levels transmitted by corresponding transmitter resonators while adjusting phases of power signals from corresponding power signal sources. The transmitter resonators can be substantially decoupled from each other by a grounded shielding mesh. In another aspect, a wireless near-field method for transferring power from a multiple transmitter subsystem to a single resonant receiver subsystem at a variable resonant power signal oscillation frequency is provided, the method comprising: providing the multiple transmitter subsystem comprising a plurality of mutually independent transmitter resonators, each of the transmitter resonators being driven by a corresponding transmitter module, the corresponding electrically connected transmitter modules being independently configurable to one of a plurality of predetermined power signal oscillation frequencies within a predetermined frequency band, wherein all of the transmitter resonators have a common emitting surface; and disposing a resonant receiver subsystem proximate the common emitting surface, the resonant receiver subsystem comprising a plurality of mutually independent transmitter resonators, each of the transmitter resonators being driven by a corresponding transmitter module, the corresponding electrically connected transmitter modules being independently configurable to one of a plurality of predetermined power signal oscillation frequencies within a predetermined frequency band. The method further includes: providing a single receiver resonator superimposed thereon; measuring one of an input impedance of each of the transmitter resonators and power drawn by each of the transmitter resonators from a test signal; setting a power signal to each of the plurality of mutually independent transmitter resonators to one of an off state and an active state based on the corresponding measured resonator input impedance and the power drawn by the corresponding transmitter resonator from the test signal; selecting a power signal oscillation frequency for each active transmitter resonator from the plurality of predetermined power oscillation frequencies based on the measured input impedance of the active transmitter resonator; and setting the power signal to each active transmitter resonator to the corresponding selected frequency. The method may further include adjusting a phase of the power signal applied to each corresponding transmitter resonator to a phase at which power transfer through the transmitter resonator is substantially maximum. In another aspect, a wireless near-field method for transmitting power from a multi-transmitter subsystem to two or more receiver subsystems at a variable resonant power signal oscillation frequency is provided, the method comprising: providing the multi-transmitter subsystem comprising a plurality of mutually independent transmitter resonators, each of the transmitter resonators being driven by a corresponding transmitter module, the corresponding transmitter module being independently configurable to one of a plurality of predetermined power signal oscillation frequencies in a predetermined frequency band, wherein all of the transmitter resonators have a common emitting surface; and arranging the two or more resonant receiver subsystems proximate to the common emitting surface, each resonant receiver subsystem comprising two or more resonant receiver subsystems connected to the common emitting surface. The method further includes: providing a single receiver resonator superimposed thereon; measuring one of an input impedance of each of the transmitter resonators and power drawn by each of the transmitter resonators from a test signal; setting a power signal to each of the plurality of mutually independent transmitter resonators to one of an off state and an active state based on the corresponding measured resonator input impedance and one of the power drawn by the corresponding transmitter resonators from the test signal; selecting a power signal oscillation frequency for each active transmitter resonator from the plurality of predetermined power oscillation frequencies based on the measured input impedance of the active transmitter resonator; and setting the power signal to each active transmitter resonator to the corresponding selected frequency. The method may further include adjusting a phase of the power signal applied to each corresponding transmitter resonator to a phase at which power transfer through the transmitter resonator is substantially maximum. In yet another aspect, a near-field wireless system for transmitting power from a photovoltaic cell to an electrical load is provided, the system comprising: a transmitter module in wired electrical communication with the photovoltaic cell, the transmitter module configured to convert the power from the photovoltaic cell into an oscillating power signal having an oscillation frequency; a transmitter resonator in wired electrical communication with the transmitter module and configured to resonate at the oscillation frequency; a receiver resonator configured to resonate at the oscillation frequency and arranged to receive power from the transmitter resonator via at least one of capacitive coupling and magnetic induction; and a receiver module in wired electrical communication with the receiver resonator, the receiver module configured to receive power from the receiver resonator and provide the received power to the electrical load in the form of direct current via the wired electrical communication. The transmit module may include a power amplifier configured to modulate power received from the photovoltaic cell at the oscillation frequency. The transmit module may include an oscillator configured to provide the oscillation frequency to the power amplifier. The transmit module may include a controller and one or more sensors, the controller configured to vary the oscillation frequency based on first information from at least one of the one or more sensors. The transmit module may include a transmission tuning network configured to, under control of the controller, vary at least the phase of power provided by the transmit module to the transmitter resonator based on second information from at least one of the one or more sensors. The system may include a power conditioning unit electrically connected between the photovoltaic cell and the transmitter module and configured to adapt the power from the photovoltaic cell to a format compatible with the transmitter module. The transmitter module may include small-signal electronic circuitry, and the power conditioning unit may be further configured to provide power to the small-signal electronic circuitry. The transmitter resonator may be disposed on a surface of the photovoltaic cell opposite an active solar radiation receiving surface of the cell. The transmitter resonator has a surface area having an extension that is at least a major portion of the extension of the active solar radiation receiving surface of the cell. The transmitter resonator may have a planar area that is smaller than a planar area of ​​the receiver resonator. The receiver resonator may be arranged and configured to receive power from the other transmitter resonator via at least one of capacitive coupling and magnetic induction at the resonant frequency. In another embodiment of a near-field wireless system for transmitting power from an array of photovoltaic cells to an electrical load, the system includes: a first plurality of transmitter modules, each transmitter module in wired electrical communication with a corresponding photovoltaic cell in the array, each transmitter module configured to convert the power from the corresponding photovoltaic cell into an oscillating power signal having an oscillation frequency; a second plurality of transmitter resonators, each transmitter resonator in wired electrical communication with a corresponding transmitter module from the first plurality of transmitter modules and configured to resonate at the oscillation frequency; a single receiver resonator configured to resonate at the oscillation frequency and arranged to receive power from the plurality of transmitter resonators via at least one of capacitive coupling and magnetic induction; and a receiver module in wired electrical communication with the receiver resonator, the receiver module configured to receive power from the receiver resonator and provide the received power to the electrical load in the form of direct current via the wired electrical communication. Each transmit module from the first plurality of transmit modules may include a power amplifier configured to modulate power received from the corresponding photovoltaic cell at the oscillation frequency. Each transmit module from the first plurality of transmit modules may include an oscillator configured to provide the oscillation frequency to the corresponding power amplifier. Each transmit module from the first plurality of transmit modules may further include a controller and one or more sensors, the controller configured to vary the oscillation frequency based on first information from at least one of the one or more sensors. Each transmit module from the first plurality of transmit modules may include a transmission tuning network configured to, under control of the corresponding controller, vary at least the phase of power provided by the transmit module to the corresponding transmitter resonator based on second information from at least one of the one or more sensors. The system may include a third plurality of power conditioning units, each power conditioning unit from the third plurality of power conditioning units being electrically connected between a corresponding photovoltaic cell and a corresponding transmitter module and configured to condition power from the corresponding photovoltaic cell into a format compatible with the corresponding transmitter module. Each transmitter module from the first plurality of transmitter modules may include small-signal electronic circuitry, and the corresponding power conditioning unit may be further configured to provide power to the small-signal electronic circuitry. Each transmitter resonator from the second plurality of transmitter resonators may be disposed on a surface of the corresponding photovoltaic cell opposite an active solar radiation receiving surface of the cell. In another embodiment of a near-field wireless system for transmitting power from an array of photovoltaic cells to an electrical load, the system includes: a first plurality of transmitter modules, each transmitter module in wired electrical communication with a corresponding photovoltaic cell in the array, each transmitter module configured to convert the power from the corresponding photovoltaic cell into an oscillating power signal having an oscillation frequency; a second plurality of transmitter resonators, each transmitter resonator in wired electrical communication with a corresponding transmitter module from the first plurality of transmitter modules and configured to resonate at the oscillation frequency; and a third plurality of receiver resonators. configured to resonate at the oscillation frequency, each receiver resonator from the third plurality of receiver resonators being configured to receive power from a corresponding transmitter resonator from the second plurality of transmitter resonators via at least one of capacitive coupling and magnetic induction; and a fourth plurality of receiver modules, each receiver module being in wired electrical communication with a corresponding receiver resonator from the third plurality of receiver resonators, the receiver modules being configured to receive power from the corresponding receiver resonator and provide the received power to an electrical load in the form of direct current via the wired electrical communication. Each transmit module from the first plurality of transmit modules may include a power amplifier configured to modulate power received from the corresponding photovoltaic cell at the oscillation frequency. Each transmit module from the first plurality of transmit modules may include an oscillator configured to provide the oscillation frequency to the corresponding power amplifier. Each transmit module from the first plurality of transmit modules may further include a controller and one or more sensors, the controller configured to vary the oscillation frequency based on first information from at least one of the one or more sensors. Each transmit module from the first plurality of transmit modules may include a transmission tuning network configured to, under control of the corresponding controller, vary at least the phase of power provided by the transmit module to the corresponding transmitter resonator based on second information from at least one of the one or more sensors. The system may further include a fifth plurality of power conditioning units, each power conditioning unit from the fifth plurality of power conditioning units being electrically connected between a corresponding photovoltaic cell from the solar cell array and a corresponding transmitter module from the first plurality of transmitter modules and configured to adapt power from the corresponding photovoltaic cell to a format compatible with the corresponding transmitter module. Each transmitter module from the first plurality of transmitter modules may include small-signal electronic circuitry, and the corresponding power conditioning unit from the fifth plurality of power conditioning units may be further configured to provide power to the small-signal electronic circuitry. Each transmitter resonator from the second plurality of transmitter resonators may be disposed on a surface of the corresponding photovoltaic cell from the photovoltaic cell array opposite an active solar radiation receiving surface of the cell. In yet another embodiment, a near-field wireless system for transmitting power from a photovoltaic cell array to an electrical load is provided. The system includes: a first plurality of transmitter modules, each transmitter module in wired electrical communication with a corresponding photovoltaic cell in the array, each transmitter module configured to convert power from the corresponding photovoltaic cell into an oscillating power signal having an oscillation frequency; a second plurality of transmitter resonators, each transmitter resonator in wired electrical communication with a corresponding transmitter module from the first plurality of transmitter modules and configured to resonate at the oscillation frequency; a third plurality of receiver resonators, fewer in number than the plurality of transmitter resonators and configured to resonate at the oscillation frequency, each receiver resonator from the third plurality of receiver resonators being configured to receive power from a portion of the plurality of transmitter resonators via at least one of capacitive coupling and magnetic induction; and a fourth plurality of receiver modules, each receiver module in wired electrical communication with a corresponding receiver resonator, the receiver modules configured to receive power from the corresponding receiver resonator and provide the received power to the electrical load in the form of direct current via the wired electrical communication. Each transmit module from the first plurality of transmit modules may include a power amplifier configured to modulate power received from the corresponding photovoltaic cell at the oscillation frequency. Each transmit module from the first plurality of transmit modules may include an oscillator configured to provide the oscillation frequency to the corresponding power amplifier. Each transmit module from the first plurality of transmit modules may further include a controller and one or more sensors, the controller configured to vary the oscillation frequency based on first information from at least one of the one or more sensors. Each transmit module from the first plurality of transmit modules may include a transmission tuning network configured to, under control of the corresponding controller, vary at least the phase of power provided by the transmit module to the corresponding transmitter resonator based on second information from at least one of the one or more sensors. The system may include a fifth plurality of power conditioning units, each power conditioning unit from the fifth plurality of power conditioning units being electrically connected between a corresponding photovoltaic cell from the photovoltaic cell array and a corresponding transmitting module from the first plurality of transmitting modules, and being configured to adapt the power from the corresponding photovoltaic cell to a format compatible with the corresponding transmitting module. Each transmitter module from the first plurality of transmitter modules may include small-signal electronic circuitry, and a corresponding power conditioning unit from the fifth plurality of power conditioning units may be further configured to provide power to the small-signal electronic circuitry. Each transmitter resonator from the second plurality of transmitter resonators may be disposed on a surface of a corresponding photovoltaic cell from the photovoltaic cell array opposite an active solar radiation receiving surface of the cell. In another aspect, a method for transmitting power from a photovoltaic cell to an electrical load is provided, the method comprising: converting power from the photovoltaic cell into an oscillating power signal having an oscillation frequency in a transmitting module; transmitting the power to a transmitter resonator in wired electrical communication with the transmitting module and configured to resonate at the oscillation frequency; receiving the power in a receiver resonator configured to resonate at the oscillation frequency and arranged to receive power from the transmitter resonator via at least one of capacitive coupling and magnetic induction; receiving the power in a receiver module in wired electrical communication with the receiver resonator; and providing the received power to the electrical load in the form of direct current via wired electrical communication. In yet another embodiment of a method for transferring power from a photovoltaic cell array to an electrical load, the method includes converting power from each of the photovoltaic cells in the array into an oscillating power signal having an oscillating frequency in each of a first plurality of corresponding transmitter modules; transferring power to a corresponding transmitter resonator from a second plurality of transmitter resonators in each of the transmitter modules, each of the transmitter resonators being configured to resonate at the oscillation frequency; receiving power in a receiver resonator configured to resonate at the oscillation frequency and arranged to receive power from the plurality of transmitter resonators via at least one of capacitive coupling and magnetic induction; receiving power in a receiver module in wired electrical communication with the receiver resonator; and providing the received power to the electrical load in the form of direct current via the wired electrical communication. In yet another embodiment of a method for transmitting power from a photovoltaic cell array to an electrical load, the method includes converting power from each of the photovoltaic cells in the array into an oscillating power signal having an oscillating frequency in each of a first plurality of corresponding transmitting modules; transmitting power from each of the transmitting modules to a corresponding transmitter resonator from a second plurality of transmitter resonators, wherein each transmitter resonator is configured to resonate at the oscillating frequency; receiving power from each transmitter resonator in a corresponding receiver resonator configured to resonate at the oscillating frequency, wherein each receiver resonator is further configured and arranged to receive power from the transmitter resonator via at least one of capacitive coupling and magnetic induction; receiving power from each receiver resonator in a corresponding receiver module in wired electrical communication with the receiver resonator; and providing the received power to the electrical load in the form of direct current via the wired electrical communication. In yet another embodiment of a method for transmitting power from a photovoltaic cell array to an electrical load, the method includes: converting power from each of the photovoltaic cells in the array into an oscillating power signal having an oscillating frequency in each of a first plurality of corresponding transmitting modules; transmitting power from each of the transmitting modules to a transmitter resonator from a second plurality of transmitter resonators, wherein each transmitter resonator is configured to resonate at the oscillating frequency; receiving power from each transmitter resonator in any proximate receiver resonator from a third plurality of receiver resonators, the receiver resonators being configured to resonate at the oscillating frequency, wherein each receiver resonator is further configured and arranged to receive power from the transmitter resonator via at least one of capacitive coupling and magnetic induction; sharing the received power among the third plurality of receiver resonators; and providing the received power in the form of direct current to the electrical load via wired electrical communication, the received power coming from one or more of the third plurality of receiver resonators via the corresponding one or more receiver modules. The method may further include converting the voltage and current of the power from each photovoltaic cell into a voltage and current suitable for a corresponding transmitting module before converting the power into the oscillating power signal. A power transmission system for supplying power from a DC power source to an electrical load is provided, the system comprising: a radio frequency power amplifier in wired electrical communication with the power source and configured to convert a DC voltage from the power source into an AC voltage signal having an oscillating frequency; an adjustable phase radio frequency rectifier in wired electrical contact with the electrical load and in radio frequency communication with the power amplifier, the rectifier configured to receive power transmitted from the amplifier; and a receiver controller in communication with the rectifier, the receiver controller configured to adjust the efficiency of power transmission from the amplifier to the rectifier by adjusting the current-voltage phase characteristic of the rectifier. The rectifier may be a differential self-synchronous radio frequency rectifier. The receiver controller may be configured to automatically adjust the current-voltage phase characteristic of the rectifier. The power transmission system may further include a load management system in wired communication with the load and disposed between the load and the rectifier in a power signaling manner, the load management system being configured to increase power transmission efficiency by adjusting the input impedance of the rectifier. The load management system may be configured to automatically adjust the current-voltage phase characteristic of the rectifier. The power transfer system may further include a transmitter controller in communication with the amplifier, the transmitter controller configured to increase the efficiency of power transfer by adjusting the current-voltage phase characteristic of the amplifier. The transmitter controller may be configured to automatically adjust the current-voltage phase characteristic of the amplifier to increase the efficiency of power transfer. The power transfer system may further include an oscillator in communication with the amplifier and the transmitter controller. The transmitter controller may be configured to adjust an oscillation frequency via the oscillator. The power amplifier may be in direct wired radio frequency communication with the adjustable phase radio frequency rectifier. The power amplifier may be in wireless near-field radio frequency communication with the adjustable phase radio frequency rectifier. The power transmission system may include: a transmitter resonator in wired radio frequency communication with the power amplifier; and a receiver resonator in wired radio frequency communication with the rectifier. The transmitter resonator and the receiver resonator may be in wireless near-field radio frequency communication with each other. The power amplifier may be in at least one of capacitive near-field wireless radio frequency communication and inductive near-field wireless radio frequency communication with the rectifier. The power amplifier may be in bimodal near-field wireless radio frequency communication with the rectifier. The DC power source may include a rechargeable battery, and the load may include an electric motor. The load may include a computer monitor. The resonant structure of the system may include at least one electrically conductive mechanical load that supports a structural component of the system. The system may further include a power conditioning unit electrically disposed between the power source and the power transmission system, the power conditioning unit configured to adjust at least one of current and voltage from the power source to improve efficiency of power transmission. Further provided is a method for transmitting power from a DC power source to an electrical load, the method comprising: providing a power transmission system in wired electrical communication with the power source, the power transmission system comprising a radio frequency power amplifier in radio frequency communication with an adjustable phase radio frequency rectifier, the adjustable phase radio frequency rectifier being in wired electrical contact with the electrical load; converting power from the DC power source into a radio frequency oscillating power signal in the amplifier; converting the radio frequency oscillating power signal into a DC power signal in the rectifier; and adjusting the efficiency of the power transmission by adjusting the current-voltage phase characteristic of the rectifier. Providing the adjustable phase radio frequency rectifier may include providing a differential self-synchronous radio frequency rectifier. The method may further include adjusting the efficiency of power transmission by adjusting the DC equivalent input resistance of the amplifier. Providing the power transmission system may include providing a load management system that performs wired communication between the rectifier and the load. Adjusting the DC equivalent input resistance of the amplifier may include adjusting the input impedance of the rectifier by adjusting the load management system. Adjusting the load management system may include automatically adjusting the load management system. The method may further include adjusting the efficiency of the power transmission by adjusting a current-voltage phase characteristic of a power amplifier. Providing the power transmission system may include providing a transmitter controller in communication with the power amplifier to control the power amplifier. Adjusting the current-voltage phase characteristic of the power amplifier may be performed by the transmitter controller. Adjusting the current-voltage phase characteristic of the power amplifier may be performed automatically by the transmitter controller. The method may further include adjusting the efficiency of power transfer by changing an oscillation frequency of the power amplifier. Providing a power transmission system may include providing a receiver controller in communication with the rectifier to control the rectifier. The adjusting of the current-voltage phase characteristic of the rectifier may be performed by the receiver controller. The adjusting of the current-voltage phase characteristic of the rectifier may be performed automatically by the receiver controller. Providing the power transfer system may include providing the power amplifier in direct wired radio frequency communication with the adjustable phase radio frequency rectifier. Providing the power transfer system may include providing the power amplifier in wireless near-field radio frequency communication with the adjustable phase radio frequency rectifier. Providing the power transfer system may include: a transmitter resonator providing wired radio frequency communication with the power amplifier; and a receiver resonator providing wired radio frequency communication with the radio frequency rectifier. The method may further include operating the transmitter resonator and the receiver resonator in wireless near-field radio frequency communication with each other. Providing the power transfer system may include providing the power amplifier in at least one of capacitive near-field wireless radio frequency communication and inductive near-field wireless radio frequency communication with the rectifier. Providing the power transfer system may include providing the receiver resonator and the power amplifier in bimodal wireless near-field communication with the rectifier. The method may further include providing a power conditioning unit electrically disposed between the power source and the power transfer system; and adjusting the power conditioning unit to adjust at least one of current and voltage from the power source to improve efficiency of power transfer. A method for transferring power from a DC power source to an electrical load is further provided, the method comprising: providing a power transfer system in wired communication with the power source, the power transfer system comprising: an oscillator capable of oscillating at an oscillation frequency; a power amplifier and a transmitter tuning network, both of which are under the control of a transmitter controller; and a receiver tuning network and a load management system, both of which are under the control of a receiver controller, the load management system being in wired communication with the electrical load; converting power from the power source into an oscillating power signal having an oscillation frequency in the power amplifier; transmitting the power signal from the power amplifier to the load management system via the transmitter tuning network and the receiver tuning network under the control of the transmitter controller; adjusting at least one of the oscillation frequency, the input DC equivalent resistance of the power amplifier, the transmitter tuning network, the receiver tuning network, and the load management system to change the rate of power transfer; and providing the power received by the load management system to the electrical load in the form of DC power via wired communication. Transmitting the power signal via the transmitter tuning network and the receiver tuning network may include transmitting power via wired communication. Transmitting the power signal via the transmitter tuning network and the receiver tuning network may include transmitting power via wireless communication. Transmitting power via wireless communication may include transmitting power via near-field wireless communication. Transmitting power via near-field wireless communication may include transmitting power via at least one of capacitive coupling and inductive coupling. Delivering power from a DC power source may include delivering power from at least one solar cell. Delivering power from a DC power source may include delivering power from at least one solar cell. Delivering power from a DC power source may include delivering power from a power source having a varying voltage. In another embodiment, an electric system includes: a mechanical load-bearing structure having a conductive first portion; an electrical load; and a power transfer system comprising at least one radio frequency resonator configured for near-field wireless power transfer, wherein the resonator at least partially comprises the conductive first portion. The electric system may further include a rechargeable battery, and the electrical load may include an electric motor. The electric system may be an electric vehicle, and the mechanical load-bearing structure may include a chassis of the vehicle. The electric system may be a display monitor, and the mechanical load-bearing structure may be at least one of a frame and a base of the monitor. The power system may further include a power supply. The power transmission system may include: a radio frequency power amplifier in wired electrical communication with the power supply and configured to convert a direct current voltage from the power supply into an alternating current voltage signal having an oscillating frequency; an adjustable phase radio frequency rectifier in wired electrical contact with the power load and in radio frequency communication with the power amplifier, the rectifier configured to receive power transmitted from the amplifier; and a receiver controller in communication with the rectifier, the receiver controller configured to adjust the efficiency of power transmission from the amplifier to the rectifier by adjusting the current-voltage phase characteristic of the rectifier. In another embodiment, an apparatus includes: a mechanical load-bearing structure having a conductive first portion; a power source; an electrical load; and a power transfer system comprising: an RF power amplifier in wired electrical communication with the power source and configured to convert a direct current voltage from the power source into an alternating current voltage signal having an oscillating frequency; an adjustable phase RF rectifier in wired electrical connection with the electrical load and in RF communication with the power amplifier, the rectifier configured to receive power transferred from the amplifier; and a receiver controller in communication with the rectifier, the receiver controller configured to adjust the efficiency of power transfer from the amplifier to the rectifier by adjusting a current-voltage phase characteristic of the rectifier; wherein the conductive first portion is configured to carry at least one of an RF signal from the amplifier and an RF signal to the rectifier. The device may further include a load management system in wired communication with the load and disposed between the load and the rectifier in a power signal manner, the load management system configured to increase power transmission efficiency by adjusting the input impedance of the rectifier. The device may further include a transmitter controller in communication with the amplifier, the transmitter controller configured to increase power transmission efficiency by adjusting the current-voltage phase characteristic of the amplifier. The device may further include an oscillator in communication with the amplifier and the transmitter controller, wherein the transmitter controller is configured to adjust the oscillation frequency via the oscillator. The power amplifier may be in direct wired RF communication with the rectifier via the conductive first portion. The power amplifier may be in wireless near-field RF communication with the rectifier. The power transfer system may include: a transmitter resonator in wired RF communication with the power amplifier; and a receiver resonator in wired RF communication with the rectifier, and one of the transmitter resonator and the receiver resonator may include the conductive first portion. The transmitter resonator and the receiver resonator may be in wireless near-field RF communication with each other. The power amplifier may be in at least one of capacitive near-field wireless RF communication and inductive near-field wireless RF communication with the rectifier. The power amplifier may be in bimodal near-field wireless RF communication with the rectifier. The DC power supply may include a rechargeable battery, and the load may include an electric motor. In certain embodiments, a sealed bidirectional power transmission circuit device includes a plurality of terminals configured for electrical communication with a device external to the sealed device. The sealed device includes, within the sealed interior, a multi-terminal power switching device having at least one DC terminal, at least one AC terminal, and at least one control terminal. The multi-terminal power switching device is adjustable between an amplifying state and a rectifying state and is configured to: bidirectionally transmit a DC voltage and a DC current via the at least one DC terminal; and bidirectionally transmit a radio frequency power signal having an amplitude, a frequency, and a phase via the at least one AC terminal. A phase, frequency, and duty cycle adjustment circuit is in wired electrical communication with a controller via the at least one control terminal and is configured to: establish a radio frequency oscillation signal having the frequency and phase of the radio frequency power signal at the at least one control terminal of the power switching device; and adjust the power switching device between the amplifying state and the rectifying state by adjusting the phase of the radio frequency oscillation signal under the control of the controller. In certain embodiments, the controller may be disposed within the sealed interior of the sealed bidirectional power transmission circuit device. The plurality of terminals of the sealed power transfer circuit device may include terminals for data communication between the controller and devices outside the sealed interior. The RF power signal may have a duty cycle, and the phase, frequency, and duty cycle adjustment circuit may be further configured to adjust the duty cycle of the RF power signal by adjusting the duty cycle of the RF oscillation signal. The phase, frequency, and duty cycle adjustment circuit may include a RF oscillator for generating the RF oscillation signal under instructions from the controller. The sealed power transmission circuit device may further include a tuning network within the seal for wired data communication with the controller, the tuning network being in wired electrical communication with the power switching device via the at least one AC terminal, the tuning network being arranged to adjust the RF power signal to a tuned RF power signal under instructions from the controller. The bidirectional power transmission circuit device may include a modulator configured to modulate information onto the RF power signal. The modulator includes the tuning network. The modulator may be configured to modulate the RF power signal using information provided by the controller. The tuning network may include a harmonic termination network circuit configured to suppress harmonics of the RF oscillation signal in the RF power signal. The harmonic termination network may include one or more inductors and one or more of a first harmonic termination, a second harmonic termination, and a third harmonic termination. The sealed power transmission circuit assembly may further include an amplitude / frequency / phase detector within the seal in wired data communication with the controller, the amplitude / frequency / phase detector being configured for wired electrical communication with the tuning network and arranged to determine the amplitude, frequency, and phase of any RF power signal transmitted between the tuning network and an AC load / source external to the sealed assembly. The tuning network may further include one or more of a compensation network, a matching network, and a filter. The phase, frequency, and duty cycle adjustment circuitry can be arranged to receive instructions from the controller based on measurement data transmitted to the controller by the amplitude / frequency / phase detector. The phase, frequency, and duty cycle adjustment circuitry can be configured to adjust the RF oscillating signal based on a feedback signal received directly from the amplitude / frequency / phase detector. The tuning network can include a voltage-current tuner configured to adjust the phase difference between the voltage and current of the tuned RF power signal based on measurement data from the amplitude / frequency / phase detector when the power switching device is in the amplification state. The sealed power transmission circuit device may further include a power management circuit within the seal for wired communication between the power switching device and a DC power source / load external to the sealed device, the power management circuit being configured to impedance-match the power switching device to the external DC power source / load and to adjust the DC power transmitted between the power switching device and the DC power source / load based on feedback signals received directly from the amplitude / frequency / phase detector. In other embodiments, the sealed power transmission circuit device may further include a power management circuit within the seal for wired data communication with the controller and between the power switching device and a DC power source / load external to the sealed device, the power management circuit being configured to impedance-match the power switching device to the external DC power source / load and to adjust the DC power transmitted between the power switching device and the DC power source / load based on measurement data transmitted to the controller by the amplitude / frequency / phase detector. The sealed power transmission circuit device may further include a voltage / current detector within the sealed interior in wired data communication with the controller, the voltage / current detector configured to determine the DC voltage and DC current transmitted between the power switching device and the power management circuit. The phase, frequency, and duty cycle adjustment circuit may be configured to receive instructions from the controller based on measurement data transmitted to the controller by the voltage / current detector. In other embodiments, the phase, frequency, and duty cycle adjustment circuit may be configured to adjust the RF oscillation signal based on feedback signals received directly from the voltage / current detector. The sealed power transmission circuit device may further include a memory within the sealed interior for wired data communication with the controller, the amplitude / frequency / phase detector, and the voltage / current detector, wherein the memory is configured to receive and store measurement data from the two detectors and provide signal data from the two detectors to the controller. The sealed power transmission circuit device may further include a power management circuit within the seal for wired electrical communication between the power switching device and the AC power source / load outside the sealed device, the power management circuit being configured to match the amplitude, frequency, and phase of the power switching device and the external AC power source / load, and to adjust the AC power transmitted between the power switching device and the AC power source / load based on feedback signals received directly from the amplitude / frequency / phase detector. The sealed power transmission circuit device may further include a power management circuit within the seal for wired data communication with the controller and for wired electrical communication between the power switching device and the AC power source / load outside the sealed device, the power management circuit being arranged to match the amplitude, frequency, and phase of the transmission power switching device with the external AC power source / load, and to adjust the DC power transmitted between the power switching device and the AC power source / load based on measurement data transmitted by the amplitude / frequency / phase detector to the controller. The sealed power transmission circuit device may further include a voltage / current detector in wired data communication with the controller within the seal, the voltage / current detector being configured to determine the DC voltage and DC current transmitted between the power switching device and the power measurement circuit. In some embodiments, the phase, frequency, and duty cycle adjustment circuit is arranged to receive instructions from the controller based on measurement data transmitted to the controller by the voltage / current detector. In some embodiments, the phase, frequency, and duty cycle adjustment circuit is arranged to adjust the RF oscillating signal based on feedback signals received directly from the voltage / current detector. The sealed power transmission circuit device may further include a memory within the sealed interior in wired data communication with the controller, the amplitude / frequency / phase detector, and the voltage / current detector, wherein the memory is arranged to receive and store measurement data from the two detectors and provide signal data from the two detectors to the controller. The sealed power transmission circuit device may further include at least one of Bluetooth communication circuitry, WiFi communication circuitry, Zigbee communication circuitry, and cellular communication technology circuitry within the sealed interior for transmitting information between the controller and devices external to the sealed power transmission circuit device. The communication circuitry may be capable of bidirectional wired communication with at least one communication antenna, which is configured to communicate with devices external to the sealed power transmission circuit device. The antenna for the communication circuitry may be disposed within the sealed interior of the sealed device. The bidirectional power transmission circuit device may include a modulator configured to modulate information onto at least one of the RF power signal and the DC voltage. The modulator may include the power switching device. The modulator may be configured to modulate at least one of the RF power signal and the DC voltage using information provided by the controller. The modulator may further include the phase, frequency, and duty cycle adjustment circuit. In some embodiments, all circuit elements of the bidirectional power transmission circuit device can be monolithically integrated into a single silicon crystal wafer. In some embodiments, at least a portion of the circuit elements of the device can be integrated using flip-chip technology. In one specific embodiment, the electronic circuitry of the sealed bidirectional power transmission circuit device can be implemented within a single silicon single crystal wafer in conjunction with at least one photovoltaic cell serving as a DC source / load. In another embodiment, the electronic circuitry of the sealed bidirectional power transmission circuit device can be implemented within a single silicon single crystal wafer in conjunction with at least one photovoltaic cell serving as a DC source / load 700 and a resonator structure serving as an AC load / source on a surface of the silicon single crystal wafer. Antennas for Bluetooth, WiFi, Zigbee, and cellular technologies can also be integrated onto the same single silicon single crystal wafer. In another aspect, a power transmission system for transmitting power between a DC source and a variable load is provided. A first self-synchronous radio frequency rectifier / amplifier and a second self-synchronous radio frequency rectifier / amplifier are configured to extract a first high-frequency (HF) power signal and a second high-frequency (HF) power signal from the DC source at a first high-frequency frequency and a second high-frequency frequency, respectively. A high-frequency power link system is configured to receive and mix the first high-frequency power signal and the second high-frequency power signal to generate a transmitted power signal. A power signal conversion circuit, in communication with the high-frequency power link system and the variable load, is configured to generate an output power signal from the transmitted power signal and supply the output power signal to the variable load. The power transmission system further includes a high-frequency switching signal generator configured to supply a first switching signal and a second switching signal to the first rectifier / amplifier and the second rectifier / amplifier at respective first and second high-frequency frequencies, and to establish and control a phase relationship between the first switching signal and the second switching signal. The power signal conversion circuit includes: a switching mode rectifier configured to receive the transmitted power signal from the high-frequency power link system and rectify the transmitted power signal to generate a rectified power signal; and an expansion circuit configured to receive the rectified power signal from the switching mode rectifier and expand the rectified power signal to generate the output power signal. The first self-synchronous RF rectifier / amplifier and the second self-synchronous RF rectifier / amplifier can be configured to operate in a rectifier mode, and the switch-mode rectifier can be configured to operate in a normally-on mode, thereby allowing power to be extracted from the variable load and delivered to the DC source via the power signal conversion circuit and the high-frequency power link system. The expansion circuit can be configured to receive a reference signal from the variable load to expand the rectified power signal in synchronization with the signal in the variable load. The power signal conversion circuit, the high-frequency power link system, and the plurality of pairs of self-synchronous RF rectifiers / amplifiers can be configured to transmit control information from the rest of the system to the high-frequency switching signal generator. The system can further include one or more controllers that communicate data with a plurality of components of the system and are configured to control the plurality of components. The system can further include: an isolable load information circuit configured to transmit information about at least one of the DC level, frequency, and phase of the power signal in the variable load to the high-frequency switching signal generator. The load information circuit can include a phase-locked loop. The load information circuit can further include an isolator system, which can include an air gap. The high-frequency power link system can include a wireless power link system, which can be a dual-peak wireless high-frequency power link system. The high-frequency power link system can include a wired power link system. In two phase difference-based embodiments, the first high-frequency frequency and the second high-frequency frequency are the same frequency; and the first switching signal and the second switching signal can have a mutual phase difference that can be adjusted by the high-frequency switching signal generator. In the first phase difference-based embodiment, the high-frequency switching signal generator is configured to adjust the mutual phase difference between the first switching signal and the second switching signal based on the DC level in the variable load, thereby generating the transmitted power signal from the high-frequency power link system as a DC signal adjusted accordingly in amplitude. In the second phase difference-based embodiment, the high-frequency switching signal generator is configured to modulate the mutual phase difference between the first switching signal and the second switching signal at a phase modulation frequency derived from the frequency of the power signal in the variable load, thereby generating the transmitted power signal from the high-frequency power link system as an AC power signal modulated at the frequency of the power signal in the variable load. In a frequency difference-based embodiment, the first high-frequency frequency and the second high-frequency frequency differ by a difference frequency ∆f. In this embodiment, the high-frequency switching signal generator is configured to determine the first high-frequency frequency and the second high-frequency frequency and set the difference frequency ∆f to double the frequency of the power signal in the variable load. The high-frequency power link system is configured to generate the transmitted power signal at the difference frequency ∆f, and the power signal conversion circuit is configured to supply the output power signal to the variable load at the frequency of the power signal in the variable load. In yet another aspect, a method for transmitting power between a DC source and a variable load is provided, the method comprising: extracting corresponding first and second high-frequency (HF) power signals from the DC source at first and second HF frequencies via corresponding first and second self-synchronous RF rectifiers / amplifiers; receiving and mixing the first and second HF power signals in a HF power link system to generate a transmitted power signal; generating an output power signal from the transmitted power signal in a power signal conversion circuit that communicates with the HF power link system and the variable load; and supplying the output power signal to the variable load. The method may further include: generating a first switching signal and a second switching signal in a high-frequency switching signal generator, and transmitting the first switching signal and the second switching signal to the first rectifier / amplifier and the second rectifier / amplifier at respective first and second high-frequency frequencies; and establishing and controlling a phase relationship between the first switching signal and the second switching signal in the high-frequency switching signal generator. The method may further include: receiving the transmitted power signal from the high-frequency power link system and rectifying the transmitted power signal in a switch-mode rectifier of the power signal conversion circuit; and receiving the rectified power signal from the switch-mode rectifier and expanding the rectified power signal in an expansion circuit of the power signal conversion circuit. The method may further include: setting the first self-synchronous RF rectifier / amplifier and the second self-synchronous RF rectifier / amplifier to a rectification mode; setting the switch-mode rectifier to a normally-on mode; extracting power from the variable load; and transmitting the extracted power to the DC source via the power signal conversion circuit and the high-frequency power link system. The method may further include: developing the rectified power signal synchronized with the signal in the variable load based on a reference signal from the variable load; transmitting control information from the rest of the system to the high-frequency switching signal generator via the power signal conversion circuit, the high-frequency power link system, and the first self-synchronous RF rectifier / amplifier and the second self-synchronous RF rectifier / amplifier; controlling the plurality of components of the system with one or more controllers in data communication with the plurality of components; and transmitting information about at least one of the DC level, frequency, and phase of the power signal in the variable load to the high-frequency switching signal generator using an isolable load information circuit including a phase-locked loop and an optional isolator system. Transmitting the power signal in the high-frequency power link system may include transmitting the power signal wirelessly, transmitting the power signal bimodally wirelessly, or transmitting the power signal wiredly. Two methods for transferring power from the DC source to the variable load utilize a phase difference between switching signals. In these embodiments, the first switching signal and the second switching signal can have the same frequency and a mutual phase difference that can be adjusted by the high-frequency switching signal generator. The method for the first of these embodiments includes: adjusting the mutual phase difference between the first switching signal and the second switching signal based on the DC level in the variable load to generate the transferred power signal from the high-frequency power link system as a DC signal that is correspondingly adjusted in amplitude. The method for the second of these embodiments includes: modulating the mutual phase difference between the first switching signal and the second switching signal at a phase modulation frequency derived from the frequency of the power signal in the variable load to generate the transferred power signal from the high-frequency power link system as an AC power signal modulated at the frequency of the power signal in the variable load. A method for a frequency difference-based implementation includes: determining first and second high-frequency frequencies of corresponding first and second switching signals; and setting the frequency difference to be equal to twice the frequency of a power signal in a variable load. The method further includes: generating a transmitted power signal from a high-frequency power link system at the frequency difference; and supplying the output power signal to the variable load at the frequency of the power signal in the variable load. The power transmission system described herein utilizes a phase or frequency difference between the switching signals supplied to a pair of self-synchronous radio frequency rectifier / amplifiers to transmit AC or DC power from a DC source to a variable load. This variable load can be expanded to transmit power from a single DC source to a single variable load via multiple rectifier / amplifier pairs, and to transmit power from multiple DC sources to a single variable load using multiple rectifier / amplifier pairs. Apparatus and methods for achieving these objectives are described. In certain embodiments, these apparatus and methods also allow for the simultaneous transmission of DC and AC power to a load. In one embodiment, a solar panel system for generating electricity and delivering the electricity to an AC load is provided, the system comprising: a planar transparent solar cover having a first planar solar cover surface and a second planar solar cover surface; at least one photovoltaic cell disposed on the first solar cover surface, the at least one photovoltaic cell having a planar photosensitive surface facing the solar cover; a high-frequency power module disposed on the first solar cover surface and corresponding to each photovoltaic cell, the high-frequency power module having a printed circuit board, the printed circuit board carrying a high-frequency power circuit for wired electrical communication with the corresponding at least one photovoltaic cell on a planar surface of the printed circuit board facing away from the solar cover; a conformal encapsulation layer bonded to a planar surface of the solar cover and covering the at least one photovoltaic cell and the corresponding high-frequency power module; and a frame carrying a single aggregator for receiving power from the at least one high-frequency power circuit and for delivering the power to the AC load at the AC load line frequency. The high-frequency power circuit can be disposed on a planar surface of the printed circuit board facing away from the solar cover. The at least one planar printed circuit board can be disposed proximate to the corresponding at least one photovoltaic cell. The at least one photovoltaic cell can be arranged in an array. All high-frequency power circuits can be phase-locked to each other. All high-frequency power circuits can be phase-locked to each other via a phase-locked loop (PLL) to the AC power signal in the AC load. In certain embodiments, the aggregator may be configured to receive power from the at least one high-frequency power circuit via wireless power transmission. The aggregator may be configured to receive power from the at least one high-frequency power circuit via bimodal wireless power transmission. Each of the high-frequency power circuits may include a transmitter resonator configured to receive power from the corresponding at least one photovoltaic cell. The system may include a receiver resonator configured to receive power from the transmitter resonator. The aggregator may include: a low-frequency expansion circuit; a switch-mode rectifier; and a receiver module configured to receive power from the receiver resonator via wired communication. The receiver resonator may be mounted in the frame. The aggregator may be mounted on the receiver resonator. In certain embodiments, the aggregator can be configured to receive power from the at least one high-frequency power circuit via wired power transmission at a low frequency. Each of the high-frequency power circuits can include: a transmitter module configured to receive power from the corresponding at least one photovoltaic cell; a receiver module in wired communication with the transmitter module to receive power from the transmitter module at a high frequency; and a switched-mode rectifier that provides a low-frequency power signal. The aggregator can include an unfolding circuit capable of receiving power from the high-frequency power circuit at the low frequency and delivering the power to the AC load at the AC load line frequency. The first solar cover surface may include an optically transparent polymeric layer. The system may include a dielectric protective cap over the high-frequency power circuit. The protective cap may be positioned above or below the conformal encapsulation layer. The perimeter of the protective cap may be positioned below and sealed to the conformal encapsulation layer. A method for manufacturing a solar panel is provided, the method comprising: arranging at least one photovoltaic cell and a high-frequency power module on a planar surface of a transparent solar cover, the at least one photovoltaic cell having a photosensitive surface facing a surface of the transparent solar cover, the high-frequency power module including a high-frequency power circuit on a printed circuit board that performs wired communication with the at least one photovoltaic cell for collecting power from the at least one photovoltaic cell, wherein the high-frequency power circuit is arranged on a planar surface of the printed circuit board facing away from the transparent solar cover; arranging a thermally deformable polymer sheet on a side of the at least one photovoltaic cell opposite to the transparent solar cover, the thermally deformable polymer sheet The polymer sheet is extended over the surface area of ​​the transparent solar cover to form a laminated stack in a plane; the laminated stack is transferred to a vacuum oven; a vacuum is established in the vacuum oven to remove air between the layers of the laminated stack; the laminated stack is heated to a deformation temperature of the heat-deformable polymer sheet; pressure is applied to the stack perpendicular to the plane; an ambient air pressure is restored in the vacuum oven to bond the heat-deformable polymer sheet to the transparent solar cover and force the heat-deformable polymer sheet to conformally bond to the at least one photovoltaic cell and the high-frequency power module to form an encapsulated photovoltaic module array; and the encapsulated photovoltaic module array is mounted in a frame. The method may further include disposing a transparent heat-crosslinkable polymer sheet on the transparent solar cover before disposing the at least one photovoltaic cell and the high-frequency power module on the transparent solar cover. Disposing the heat-deformable polymer sheet may include disposing a heat-deformable crosslinkable polymer sheet. Disposing the heat-deformable crosslinkable polymer sheet may include disposing a sheet comprising one or more layers of one or more of the following materials: polyethylene terephthalate, biaxially oriented polyethylene terephthalate, ethylene vinyl acetate, fluorinated polyester, polyvinyl fluoride, polyvinylidene fluoride, polyethylene vinyl acetate, polyethylene naphthalate, ethylene tetrafluoroethylene, fluorovinyl ether, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer, polyamide, polypropylene, polyethylene, and polyvinylidene fluoride short sugar palm fiber. Mounting the packaged photovoltaic module array in a frame may include mounting the packaged photovoltaic module array in a frame carrying a receiver resonator and an aggregator, the aggregator configured to receive a power signal from the high-frequency power circuit via the receiver resonator. Mounting the packaged photovoltaic module array in a frame may include mounting the packaged photovoltaic module array in a frame carrying an aggregator, the aggregator configured to receive a power signal from the high-frequency power circuit via a wire. If a solar panel system is considered without considering the packaging of the photovoltaic modules, it can be described as a solar panel system for generating electricity and delivering the electricity to an AC load, the system comprising: at least one photovoltaic cell, corresponding to each photovoltaic cell, a high-frequency power module in wired electrical communication with the corresponding at least one photovoltaic cell; and a frame that carries a single aggregator, the aggregator being arranged to receive power from the at least one high-frequency power module and to deliver the power to the AC load at an AC load line frequency. All of the at least one high-frequency power modules are capable of being phase-locked to an AC power signal in the AC load via a phase-locked loop. Each of the at least one high-frequency power modules may include: a high-frequency switching signal generator capable of being phase-locked to a power signal in the AC load having the AC load line frequency; a first high-frequency switch-mode power rectifier / amplifier and a second high-frequency switch-mode power rectifier / amplifier for providing corresponding first and second high-frequency power signals from power generated by the corresponding at least one photovoltaic cell, the frequencies of the corresponding first and second high-frequency power signals differing by an amount equal to twice the AC load line frequency. The aggregator of the solar panel system may include an unfolding circuit arranged to receive power emitted from each of the at least one photovoltaic cell at a frequency twice the AC load line frequency. In certain embodiments, the aggregator of the solar panel system is configured to receive power from the at least one high frequency power module via wireless power transfer. In certain embodiments, the aggregator of the solar panel system can be configured to receive power from at least one high-frequency power module via bimodal wireless power transfer. In these embodiments, each of the high-frequency power modules includes a transmitter resonator in wired communication with a transmitter module, the transmitter resonator configured to receive power from the corresponding at least one photovoltaic cell. The solar power system also includes a single receiver resonator configured to receive power from the transmitter resonator corresponding to the at least one photovoltaic cell via bimodal power transfer. The aggregator includes: a low-frequency expansion circuit; a switch-mode rectifier; and a receiver module configured to receive power from the receiver resonator via wired communication. The receiver resonator can be mounted in the frame, and the aggregator can be mounted on the receiver resonator. In another embodiment, the aggregator of the solar panel system can be configured to receive power from the at least one high-frequency power module via low-frequency wired power transmission. Each of the high-frequency power modules includes: a transmitter module configured to receive power from the corresponding at least one photovoltaic cell; a receiver module in wired communication with the transmitter module to receive power from the transmitter module at a high frequency; and a switched-mode rectifier that provides a low-frequency power signal. The aggregator includes an expansion circuit capable of receiving power from the high-frequency power module at a low frequency and delivering the power to the AC load at the AC load line frequency. In another embodiment, each of the high-frequency power modules may include: a transmitter module configured to receive power from the corresponding at least one photovoltaic cell; a receiver module in wired communication with the transmitter module to receive power from the transmitter module at a high frequency; a switch-mode rectifier providing a low-frequency power signal; and an expansion circuit for expanding the low-frequency signal from the switch-mode rectifier. In this embodiment, the aggregator may be a device that collects all expanded signals from each of the expansion circuits associated with each of the corresponding photovoltaic cells only at the AC load line frequency. In the following detailed description, specific details are set forth to provide a more thorough understanding for those skilled in the art. However, well-known elements may not be shown or described in detail to avoid unnecessarily obscuring the present invention. Therefore, the present specification and drawings should be viewed in an illustrative rather than a restrictive sense. One aspect of the present invention provides a wireless power transfer system including a transmitter (also referred to as the primary side) and a receiver (also referred to as the secondary side). Another aspect provides a wireless power transmitter that can be used as part of another wireless power transfer system. Another aspect provides a wireless power receiver that can be used as part of another wireless power transfer system. According to certain embodiments, the transmitter may include a resonator configured to transmit power via inductive power transfer and / or capacitive power transfer. Similarly, according to certain embodiments, the receiver may include a resonator configured to receive power via inductive power transfer and / or capacitive power transfer. FIG1 is a simplified schematic diagram of a wireless power transfer (WPT) system 10 including a primary side 12 and a secondary side 14. The primary side 12 may also be referred to as a transmitter, while the secondary side 14 may also be referred to as a receiver. The primary side 12 includes a transmitter module 20 and a transmitter resonator 30 , while the secondary side 14 includes a receiver module 40 and a receiver resonator 50 . Transmitter module 20 receives power as input, including, for example, direct current (DC) power. Although not shown, transmitter module 20 may include, for example, an inverter, a transmitter compensation network, and / or other components as further described herein. Transmitter module 20 delivers power, including, for example, alternating current (AC) power, as output to transmitter resonator 30. The transmitter resonator 30 receives power as input from the transmitter module 20 and can output a magnetic field 31A (e.g., a time-varying magnetic field) and / or an electric field 31B (e.g., a time-varying electric field). In some embodiments, the transmitter resonator 30 outputs the magnetic field 31A for IPT purposes. In some embodiments, the transmitter resonator 30 outputs the electric field 31B for CPT purposes. In some embodiments, the resonator 30 outputs both the magnetic field 31A and the electric field 31B for simultaneous power transmission via CPT and IPT. In some embodiments, the resonator 30 can switch between outputting the electric field 31B for CPT purposes, outputting the magnetic field 31A for IPT purposes, and outputting both the magnetic field 31A and the electric field 31B for simultaneous power transmission via CPT and IPT. The adjective term "bimodal" is used herein to describe a system configured for simultaneous capacitive signaling and inductive signaling. In the presence of a magnetic field 31 A, for the purposes of IPT, a current may be induced in the receiver resonator 50. In the presence of an electric field 3 IB, an AC potential may be induced across the receiver resonator 50 (or its antenna or antennas). When current is induced in the receiver resonator 50 by the magnetic field 31A, this current can be output to the receiver module 40. Similarly, when an AC potential is induced on the receiver resonator 50 by the electric field 31B, current can be caused to flow into the receiver module 40 through the receiver resonator 50. Receiver module 40 can receive power (e.g., AC power) as input from receiver resonator 50 and can output power (e.g., DC power) to a load. The load can be a charge for an electrical storage device (such as a battery or supercapacitor). By way of non-limiting example, the load can include or be a component of an electric bicycle (also known as an e-bike or e-pedelec) (such as one that is part of a shared bike fleet), an automobile, a boat, etc. Although not shown, receiver module 40 can include, for example, a rectifier, a receiver compensation network, and / or other components as further discussed herein. For various reasons, the WPT system 10 can be configured to adjust the ratio of power transferred from the transmitter module 20 to the receiver module 40 via CPT to power transferred from the transmitter module 20 to the receiver module 40 via IPT (the "transfer mode ratio"). For example, the transfer mode ratio can be adjusted to: increase the ratio of power delivered by CPT as the distance between the transmitter resonator 30 and the receiver resonator 50 increases; increase the ratio of power delivered by IPT when a living being (e.g., a human or animal) is in the vicinity of the WPT system 10; increase the ratio of power delivered by CPT when an object (e.g., a metal object) is in the vicinity of the WPT system 10; increase the ratio of power delivered by CPT when the alignment between the transmitter resonator 30 and the receiver resonator 50 deteriorates; and / or any combination of the foregoing. In some embodiments, the transmission mode ratio can be adjusted based on maximum power point tracking techniques, such as, but not limited to, "observe and perturb" techniques sometimes used for wind turbines and solar panels (e.g., see S. Dehghani, S. Abbasian, and T. Johnson, "Adjustable Load With Tracking Loop to Improve RF Rectifier Efficiency Under Variable RF Input Power Conditions," IEEE Transactions on Microwave Theory and Techniques, Vol. 64, No. 2, pp. 343-352, February 2016). In some embodiments, the transmission mode ratio can be adjusted based on a machine learning algorithm. For example, in some embodiments, if the WPT system 10 determines that the WPT efficiency is unexpectedly low, the WPT system 10 can increase the proportion of power delivered by the CPT (or IPT). If WPT efficiency is negatively impacted by increased reliance on CPT (or IPT), the WPT system 10 can reduce reliance on CPT (or IPT). This process can be repeated iteratively until a desired / maximum WPT efficiency is achieved. Each of the transmitter resonator 30 and the receiver resonator 50 may include a plurality of antennas 80 arranged in various configurations. Antenna 80 can include any suitable antenna having high self-inductance and high self-capacitance that is capable of generating both magnetic field 31A and electric field 31B (separately and / or simultaneously) for the purposes of CPT and IPT. Figures 2A, 2B, and 2C depict non-limiting examples of antennas 80, 180, and 280. For the purposes of this document, "high self-inductance" is a self-inductance that is sufficiently large to allow the antenna to generate a magnetic field suitable for the purposes of IPT. Similarly, for the purposes of this document, "high self-capacitance" is a self-capacitance that is sufficiently large to allow the antenna to generate an electric field suitable for the purposes of CPT. FIG2A depicts antenna 80 according to certain embodiments. Antenna 80 can comprise any suitable conductive material. For example, antenna 80 can comprise copper, gold, silver, aluminum, other suitable materials, or combinations thereof. As can be seen in FIG2A , antenna 80 comprises an elongated element 80A having a rectangular (e.g., square) cross-section that has been bent or formed into a generally flat rectangular (in the XY plane) coil shape, such that adjacent covering members of elongated element 80A are separated by a gap 80B. While gap 80B is depicted as being generally constant along the length of elongated element 80, this is not mandatory. To increase the self-inductance of antenna 80, the size of gap 80B can be reduced. To increase the self-capacitance of antenna 80, the number of bends (e.g., bends 82A) of elongated element 80A can be increased, the number of corners and edges (e.g., edges 82B) of elongated element 80A can be increased, the length of elongated element 80A can be increased, and / or the thickness 80C of elongated element 80A can be increased. FIG2B depicts another non-limiting example of an antenna 180 according to certain embodiments. Antenna 180 is substantially similar to first antenna 80, except that elongated element 180A, rather than being bent or formed into a generally planar rectangular coil shape, is bent or formed into a generally planar sawtooth shape with square corners, as shown in FIG2B. As with antenna 80, adjacent sawtooths of elongated element 180A are separated by gaps 180B. While gaps 180B are depicted as being generally constant along the length of elongated element 180, this is not mandatory. To increase the self-inductance of antenna 180, the size of gap 180B can be reduced. To increase the self-capacitance of antenna 180, the number of bends (e.g., bends 182A) of elongated element 180A can be increased, the number of corners and edges (e.g., edges 182B) of elongated element 180A can be increased, and / or the thickness 180C of elongated element 180A can be increased. FIG2C depicts another non-limiting example of an antenna 280 according to certain embodiments. Antenna 280 is substantially similar to first antenna 80, except that elongated element 280A, rather than being bent or formed into a generally planar rectangular coil shape, is bent or formed into a generally planar circular shape (in the XY plane) with a hub element 280A, wherein sector elements 280C extend radially outward from hub element 280A. Adjacent sector elements 280C are separated from each other by gaps 280B. To increase the self-inductance of antenna 280, the size of gap 280B can be reduced. To increase the self-capacitance of antenna 280, the number of sector elements 280C can be increased, the number of corners and edges (e.g., edges 280a) of hub element 280A and / or sector elements 280C can be increased, and / or the thickness 282C of the extended hub element 280A and / or sector elements 280C can be increased. While FIG2A , FIG2B , and FIG2C depict exemplary, non-limiting embodiments of antennas 80 , 180 , and 280 , it should be understood that antennas 80 having numerous other shapes and configurations may be employed in the resonators described herein. Non-limiting examples of changes that may be made to the illustrated antennas include: changing the cross-sectional shape of the elongated elements 80A, 180A to a non-rectangular shape (e.g., triangular, circular, hexagonal, etc.); changing the 90° bends 82A, 182A to a non-90° shape or a circular shape; changing the XY plane shape of the first radiator antenna 80 to a non-rectangular or circular shape; using a non-repeating pattern of bends and corners; and the like. While antennas 80, 180, and 280 are described and illustrated herein as being relatively flat or planar (e.g., having substantially no variation in thickness in the Z direction), this is not mandatory. In some embodiments, antennas 80, 180, and 280 may have a conical concave or convex shape, as shown in Figures 3A and 3B. For example, the antennas herein may have a conical spiral shape (not shown). In some embodiments, antenna 80 may have a rectangular conical spiral shape, such that the inner winding of antenna 80 is spaced apart from the outer winding of antenna 80 in the Z direction. Such a conical shape may allow the resonator to be used over a wider range of resonant frequencies. In other embodiments, the thickness of the first transmitter antenna in the Z direction may vary in other ways. For example, antennas 80, 180, and 280 can be arranged in a configuration similar to that of panels in a CPT WPT system. For example, in a two-antenna WPT system according to certain embodiments, the transmitter resonator 30 may include a first transmitter antenna 32 arranged in parallel with a first receiver antenna 52 of a receiver resonator 50, as shown in FIG4A . For CPT purposes, the mutual capacitance between the two antennas 32 and 52 provides a path for current to flow forward to the receiver side, while a conductive path (e.g., ground) allows current to flow back to the transmitter side. For IPT purposes, driving current through the first transmitter antenna 32 generates a magnetic field 31A that can induce current in the first receiver antenna 52. For CPT purposes, a voltage can be applied to the first transmitter antenna 32 to create a potential difference between the first transmitter antenna 32 and the first receiver antenna 52, thereby forming an electric field 31B. The first transmitter antenna 32 may include any suitable antenna having high self-inductance and high self-capacitance that is capable of forming both the magnetic field 31A and the electric field 31B (separately and / or simultaneously). For example, the first transmitter antenna may include one of antennas 80, 180, 280, or any other antenna described herein. The first receiver antenna 52 may comprise any suitable antenna having high self-inductance and high self-capacitance, capable of inducing a current therein due to the magnetic field 31A and imparting a potential difference thereon due to the electric field 31B (separately and / or simultaneously). In some embodiments, the first receiver antenna 52 may be substantially similar to the first transmitter antenna 32 (e.g., the first receiver antenna 52 may have the same characteristics as any antenna described or illustrated herein or otherwise). In some embodiments, the antennas 32 and 52 may be different from one another (e.g., the first transmitter antenna 32 may comprise antenna 80, while the first receiver antenna 52 may comprise antenna 180). In some embodiments, the XY plane area of ​​the first transmitter antenna 32 is smaller than the XY plane area of ​​the first receiver antenna 52 to improve coupling between the first transmitter antenna 32 and the first receiver antenna 52 . FIG4B illustrates another example configuration of antennas 80, 180, and 280. In certain embodiments, FIG4B illustrates a four-antenna stack (or four-antenna vertical) WPT system. Each of the transmitter resonator 130 and the receiver resonator 150 includes two antennas. One antenna of the transmitter resonator 30, together with one antenna of the receiver resonator 150, provides a forward path for power, while the other antenna of the transmitter resonator 130, together with another antenna of the receiver resonator 150, provides a return path for power. For IPT purposes, current is driven through the transmitter antennas 132, 134 to generate a magnetic field that can induce current in the first and second receiver antennas 152, 154. For CPT purposes, a potential difference can be applied between the first and second antennas 132, 134 to generate an electric field (31B shown in FIG. 1 ), thereby inducing a potential across the first and second receiver antennas 152, 154. As shown in FIG. 4B , the transmitter resonator 130 includes a first transmitter antenna 132 and a second transmitter antenna 134 separated in the Z direction by a spacer 138 . The first transmitter antenna 132 may include any suitable antenna having high self-inductance and high self-capacitance that is capable of forming both the magnetic field 31A and the electric field 31B (separately and / or simultaneously). For example, the first transmitter antenna may include one of antennas 80, 180, 280, or any other antenna described herein. Spacer 138 can comprise any suitable material. For example, spacer 138 can comprise air, a dielectric material, a ferrite, or some combination thereof. Spacer 138 can have a dielectric constant selected to modify electric field 31B and / or a permeability selected to modify magnetic field 31A. Spacer 138 can comprise a high dielectric constant material to increase the capacitance of transmitter resonator 130. The thickness and planar area of ​​spacer 138 can depend on the thickness and / or planar area of ​​first and second transmitter antennas 132 and 134. In some embodiments, electrical insulation can be desirable, and a low dielectric constant material can be employed for spacer 138 (e.g., for shielding). Second transmitter antenna 134 may comprise any suitable antenna having high self-inductance and high self-capacitance that is capable of generating both magnetic field 31A and electric field 31B (separately and / or simultaneously). In some embodiments, second transmitter antenna 134 may be substantially similar to first transmitter antenna 132 (e.g., second transmitter antenna 134 may have the same characteristics as any antenna described or illustrated herein or otherwise). In some embodiments, first and second transmitter antennas 132, 134 and first and second receiver antennas 152, 154 may be different from one another (e.g., first and second transmitter antennas 132, 134 may be similar to antenna 80, while first and second receiver antennas 152, 154 may be similar to antenna 180). In some embodiments, the size of the XY plane area of ​​the second transmitter antenna 134 can be different from the XY plane area of ​​the first transmitter antenna 132. In some embodiments, the XY plane area of ​​the second transmitter antenna 134 can be smaller than the XY plane area of ​​the first transmitter antenna 132 to ensure coupling between each pair of antennas. In some embodiments, the XY plane area of ​​the second transmitter antenna 134 can be larger than the XY plane area of ​​the first transmitter antenna 132. In certain embodiments, the second transmitter antenna 134 is substantially complementary in size and / or shape to the first antenna 132, such that the first transmitter antenna 132 and the second transmitter antenna 134 do not substantially overlap in the Z direction. FIG5 depicts a schematic representation of an XZ plane cross-section of a portion of the transmitter resonator 130, wherein the first transmitter antenna 132 and the second transmitter antenna 134 are each substantially similar in shape to the first transmitter antenna 180 of FIG2B. As can be seen, the portions 132A-1, 132A-2, 132A-3 of the elongated element 132A of the first transmitter antenna 132 overlap with the gaps 134B-1, 134B-2, 134B-3 of the second transmitter antenna 134 in the Z direction (e.g., a line oriented in the Z direction through the portion 132A-1 of the elongated element 132A of the first transmitter antenna 132 passes through the gap 134B-1 of the second transmitter antenna 134), and the portions 134A-1, 134A-2, 134A-3 of the elongated element 134A of the second transmitter antenna 134 overlap with the gaps 132B-1, 132B-2, 132B-3 of the first transmitter antenna 132 in the Z direction (e.g., a line oriented in the Z direction through the portion 134A-1 of the elongated element 134A of the second transmitter antenna 134 passes through the gap 132B-1 of the first transmitter antenna 132). The complementary shapes of the first and second transmitter antennas 132, 134 may reduce parasitic energy losses experienced by the transmitter resonator 130. In some embodiments, the first and second transmitter antennas 132, 134 may not be fully complementary, but may have one or more complementary portions. The receiver resonator 150 includes a first receiver antenna 152 and a second receiver antenna 154 separated in the Z direction by a spacer 158. The first receiver antenna 152 can be substantially similar to antennas 80, 180, 280, or any of the other antennas described herein. The second receiver antenna 154 can also be substantially similar to antennas 80, 180, 280, or any of the other antennas described herein. Like the first transmitter antenna 132 and the second transmitter antenna 134, the first receiver antenna 152 and the second receiver antenna 154 can be complementary (or partially complementary) in size and / or shape. In some embodiments, as shown in FIG4B , the XY plane area of ​​the first receiver antenna 152 and the second receiver antenna 154 is different from the XY plane area of ​​the first transmitter antenna 132 and the second transmitter antenna 134 in order to adjust the self-inductance or self-capacitance of the receiver resonator 150. For example, in some embodiments, the XY plane area of ​​the first receiver antenna 152 and the second receiver antenna 154 is larger than the XY plane area of ​​the first transmitter antenna 132 and the second transmitter antenna 134, as shown in FIG2A . This difference in XY plane area can improve the ability of the receiver resonator 150 to capture more of the magnetic field 31A and / or electric field 31B. Spacer 158 can include any suitable spacer. Spacer 158 can include the same or similar material as spacer 138, or a different material than spacer 138. Compared to spacer 158, spacer 138 can have a smaller Z-direction dimension to achieve a desired self-capacitance and / or self-inductance. This can effectively change the coupling coefficient of the link between primary side 12 and secondary side 14 and the impedance of primary side 12. Different compensation networks can be used in both primary side 12 and secondary side 14 to accommodate these coupling coefficient and impedance changes. Compared to the four-antenna parallel structure shown in Figure 4C, the stacked configuration of Figure 4B is more compact in the XY plane. Furthermore, because all antennas can be centrally aligned, this configuration is robust to angular misalignment. Specifically, when the antennas are circular, angular rotation has no effect on the coupling capacitance. However, compared to the four-antenna parallel structure shown in Figure 4C, the stacked configuration of Figure 4B can reduce the mutual conductance due to the increased cross-coupling capacitance. FIG4C illustrates another example configuration of antennas 80, 180, and 280. In certain embodiments, FIG4C illustrates a four-antenna parallel (or four-antenna horizontal) WPT system. Each of the transmitter resonator 230 and the receiver resonator 250 includes two antennas. One antenna of the transmitter resonator 230 and one antenna of the receiver resonator 250 together provide a forward path for power, while the other antenna of the transmitter resonator 230 and another antenna of the receiver resonator 250 together provide a return path for power. For IPT purposes, current is driven through the first and second transmitter antennas 232 and 234 of the transmitter to generate a magnetic field that can induce current in the first and second receiver antennas 252 and 254. For CPT purposes, a potential difference can be created between the first and second transmitter antennas 232 and 234 to generate an electric field 31B, thereby inducing a potential across the first and second receiver antennas 252 and 254. Compared to the transmitter resonator 130 and the receiver resonator 150 shown in FIG. 4B , the transmitter resonator 230 and the receiver resonator 250 having a horizontal antenna arrangement may be desirable in applications where there are limitations on the Z-direction size of the resonators. The transmitter resonator 230 includes a first transmitter antenna 232 and a second transmitter antenna 234 separated in the X direction by a spacer 238. By separating the first transmitter antenna 232 and the second transmitter antenna 234 in the X direction, parasitic energy losses can be reduced. The first transmitter antenna 232 and the second transmitter antenna 234 can be substantially similar to the first transmitter antenna 132 and the second transmitter antenna 134, and the spacer 238 can be substantially similar to the spacer 138. As with the transmitter resonator 130, the first transmitter antenna 232 can have a larger XY plane area than the second transmitter antenna 234 to improve the forward path for power transfer. Spacer 238 can comprise any suitable material. For example, spacer 238 can comprise air, a dielectric material, a ferrite, or a combination thereof. Spacer 238 can have a dielectric constant selected to modify electric field 31B and / or a permeability selected to modify magnetic field 31A. Spacer 238 can comprise a high dielectric constant material to increase the capacitance of transmitter resonator 230. The thickness and planar area of ​​spacer 238 can depend on the thickness and / or planar area of ​​first and second transmitter antennas 232 and 234. In some embodiments, electrical insulation can be desirable, and a low dielectric constant material can be employed for spacer 238 (e.g., for shielding). The receiver resonator 250 includes a first receiver antenna 252 and a second receiver antenna 254 separated in the X direction by a spacer 258. By separating the first receiver antenna 252 from the second receiver antenna 254 in the X direction, parasitic energy loss can be reduced. The first receiver antenna 252 and the second receiver antenna 254 can be substantially similar to the first receiver antenna 152 and the second receiver antenna 154, and the spacer 258 can be substantially similar to the spacer 138. As with the receiver resonator 150, the first receiver antenna 252 can have a larger XY plane area than the XY plane area of ​​the second receiver antenna 254. Spacer 258 can include any suitable spacer. Spacer 258 can include the same or similar material as spacer 238, or a different material than spacer 238. Compared to spacer 258, spacer 238 can have a smaller Z-direction dimension to achieve a desired self-capacitance and / or self-inductance. This can effectively change the coupling coefficient of the link between primary side 12 and secondary side 14 and the impedance of primary side 12. Different compensation networks can be used in both primary side 12 and secondary side 14 to accommodate these coupling coefficient and impedance changes. In some embodiments, the XY plane area of ​​the spacer 258 may be different than the XY plane area of ​​the spacer 238 in order to vary the self-inductance or self-capacitance of the transmitter resonator 230 or the receiver resonator 250. For example, the spacer 238 may have a smaller XY plane area than the spacer 258, as shown. FIG4D depicts another example configuration of antennas 80, 180, and 280. In certain embodiments, FIG4D depicts a six-antenna WPT system combined with the stacked configuration of FIG4B and the parallel configuration of FIG4C. Each of transmitter resonator 130 and receiver resonator 150 includes three antennas. One of first transmitter antenna 332 and second transmitter antenna 334, together with one of first receiver antenna 352 and second receiver antenna 354, provides a forward path for power, while the other of first transmitter antenna 332 and second transmitter antenna 334, together with the other of first receiver antenna 352 and second receiver antenna 354, provides a return path for power. Third transmitter antenna 336 and third receiver antenna 356 function as auxiliary antennas to increase equivalent self-capacitance and act as an electric field shield. In some embodiments, the third transmitter antenna 336 and the third receiver antenna 356 are passive (e.g., no potential difference is applied between the third transmitter antenna 336 and the third receiver antenna 356 and / or no current is driven through the third transmitter antenna 336 and the third receiver antenna 356). For IPT purposes, a magnetic field that can induce current in the first receiver antenna 352, the second receiver antenna 354, and the third receiver antenna 356 is generated by driving current through one or more of the transmitter's first transmitter antenna 332, the second transmitter antenna 334, and the third transmitter antenna 336. For CPT purposes, a voltage can be applied to the first transmitter antenna 332, the second transmitter antenna 334, and / or the third transmitter antenna 336 to create a potential difference between any of the first transmitter antenna 332, the second transmitter antenna 334, and the third transmitter antenna 336, thereby forming an electric field 31B. The transmitter resonator 330 includes a first transmitter antenna 332 and a second transmitter antenna 334 separated in the X direction by a spacer 338, and a third transmitter antenna 336 separated from the first and second transmitter antennas and the spacer 338 by a second spacer 339. The third transmitter antenna 336 can provide electric field shielding to reduce undesirable escape of electric fields from the transmitter resonator 330. The third transmitter antenna 336 can include a ferrite sheet or surface to provide magnetic field shielding to reduce undesirable escape of magnetic fields from the transmitter resonator 330. By varying the spacer 339, shielding or shaping of electric or magnetic fields is also possible. The first transmitter antenna 332, the second transmitter antenna 334, and the third transmitter antenna 336 may be substantially similar to either the first transmitter antenna 132 or the second transmitter antenna 134. The spacers 338, 339 may be substantially similar to the spacer 138. As with the transmitter resonator 130, the first transmitter antenna 332 may have a larger XY plane area than the second transmitter antenna 334. The third transmitter antenna 336 may have a larger XY plane area than either the first transmitter antenna 332 or the second transmitter antenna 334. The spacers 338 and 339 can comprise any suitable material. For example, the spacers 338 and 339 can comprise air, a dielectric material, a ferrite, or a combination thereof. The spacers 338 and 339 can have a dielectric constant selected to modify the electric field 31B and / or a permeability selected to modify the magnetic field 31A. The spacers 338 and 339 can comprise a high dielectric constant material to increase the capacitance of the transmitter resonator 230. The thickness and planar area of ​​the spacers 338 and 339 can depend on the thickness and / or planar area of ​​the first transmitter antenna 332, the second transmitter antenna 334, and the third transmitter antenna 336. In some embodiments, electrical isolation may be desirable, and a low dielectric constant material may be employed for the spacers 338 and 339 (e.g., for shielding). Receiver resonator 350 includes a first receiver antenna 352 and a second receiver antenna 354 separated in the X direction by a spacer 358; and a third receiver antenna 356 separated from the first and second receiver antennas and spacer 358 by a second spacer 359. Third receiver antenna 356 can provide electric field shielding to reduce unwanted electric field leakage from receiver resonator 350. Third receiver antenna 356 can include a ferrite sheet or surface to provide magnetic field shielding to reduce unwanted magnetic field leakage from the transmitter. By varying spacer 359, shielding or shaping of electric or magnetic fields is also possible. First, second, and third receiver antennas 352, 354, and 356 can be substantially similar to either first or second receiver antenna 152, 154. Spacers 358 and 359 can be substantially similar to spacer 158. As with receiver resonator 150, first receiver antenna 352 can have a larger XY plane area than second receiver antenna 354. The third receiver antenna 356 may have a larger XY plane area than either the first receiver antenna 352 or the second receiver antenna 354 . Spacers 358 and 359 can comprise any suitable spacer. Spacers 358 and 359 can comprise the same or similar material as spacers 338 and 339, or a different material than spacers 338 and 339. Compared to spacers 358 and 359, spacers 338 and 339 can have a smaller Z-direction dimension to achieve a desired self-capacitance and / or self-inductance. This can effectively change the coupling coefficient of the link between primary side 12 and secondary side 14 and the impedance of primary side 12. Different compensation networks can be used in both primary side 12 and secondary side 14 to accommodate these coupling coefficient and impedance changes. In some embodiments, the XY plane area of ​​spacer 358 can differ from the XY plane area of ​​spacer 338 to vary the self-inductance or self-capacitance of transmitter resonator 330 or receiver resonator 350. For example, spacer 338 can have a smaller X-direction dimension than spacer 358. In some embodiments, the Z-direction dimension of spacer 359 can differ from the Z-direction dimension of spacer 339 to vary the self-inductance or self-capacitance of transmitter resonator 330 or receiver resonator 350. For example, spacer 339 can have a smaller Z-direction dimension than spacer 359. This can effectively change the coupling coefficient between primary side 12 and secondary side 14 and the impedance of primary side 12. Different compensation networks can be used in both primary side 12 and secondary side 14 to accommodate these coupling coefficient and impedance variations. In some embodiments, magnetic shielding may be provided around one or more of the transmitter resonator 30 and the receiver resonator 50. For example, ferrite may be used as a magnetic shield and to reduce undesirable eddy currents in nearby metal objects. Ferrite (or another suitable material) may also be used to isolate the transmitter resonator 30 and / or the receiver resonator 50 from surrounding metal objects and, therefore, may be used to increase the antenna's self-inductance and / or the resonator's mutual inductance. 6 depicts a schematic diagram of the primary side 12 including the transmitter module 20 and the transmitter resonator 30 according to certain embodiments. The transmitter resonator 30 may include any of the transmitter resonators 30, 130, 230, 330, or other transmitter resonators described herein. The transmitter module 20 includes a controller 22. The controller 22 is configured to receive various inputs from sensors 24 (e.g., load detector 24A, transmitter power sensor 24B, surrounding object detector 24C, and / or distance detector 24D) and output control signals to various components 26 (e.g., oscillator 26A, power amplifier 26B, filter network 26C, matching network 26D, compensation network 26E, and V / I tuner 26F). Load detector 24A is configured to detect the presence of a load 70 (shown in FIG. 7 ) connected to secondary side 14 . For example, load 70 may be a battery for an electric vehicle (such as an electric bicycle or electric car), or any other suitable item requiring power input. Load detector 24A may be implemented using physical sensors (such as, without limitation, optical sensors, pressure sensors, infrared sensors, or proximity sensors) and suitable software or firmware. For example, in some embodiments, power (e.g., current and voltage) is measured at, for example, point 24E to determine the power drawn by transmitter resonator 30 (e.g., as measured by transmitter power sensor 24B). If the amount of power drawn by transmitter resonator 30 increases above a baseline, load detector 24A may signal the presence of load 70 to controller 22 . In other embodiments, load detector 24A can be configured to measure the input impedance of transmitter resonator 30 as seen by transmitter module 20 at point 24E. The presence of a resonant load (including, for example, secondary side 14 configured to drive load 70) in proximity to transmitter resonator 30 will change the input impedance of transmitter resonator 30. This change in impedance, provided by load detector 24A to controller 22, can be used by transmitter controller 22 to determine whether a cooperating receiver is in proximity to transmitter resonator 30. The impedance changes induced in transmitter resonator 30 by different receivers are different and characteristic, making it possible for controller 22 to not only detect the presence or absence of a receiver in proximity to transmitter resonator 30, but also to identify the type of receiver, including, without limitation, different models of mobile phones or digital tablets. The transmitter power sensor 24B can measure the power (e.g., current and voltage) at point 24E to determine how much power is being drawn by the transmitter resonator 30. This information can be used, for example, by the load detector 24A to determine whether there is a desired, efficient coupling between the transmitter resonator 30 and the receiver resonator 50. The surrounding object detector (SOD) 24C is configured to determine whether an object (e.g., a living being such as a person or animal, or a piece of metal or other static object) is in proximity to the transmitter resonator 30. The SOD 24C can be implemented using a physical sensor (e.g., without limitation, an optical sensor, a pressure sensor, an infrared sensor, a proximity sensor, a radar, or a lidar) or with the aid of suitable software or firmware. For example, if the power drawn by the transmitter resonator 30 (as measured by the transmitter power sensor 24B) decreases during IPT, the SOD's software can determine that a piece of metal (or any electrical conductor) is in proximity to the transmitter resonator 30 or the receiver resonator 50, and the SOD can provide a signal indicating this presence to the controller 22. In certain embodiments, if a metal object is detected in proximity to the transmitter resonator 30 or the receiver resonator 50, the controller 22 can cause the transmitter module 20 to increase the proportion of power delivered by the CPT. When the SOD 24C detects the absence of a living being, the controller 22 can be configured to increase the power supply to the transmitter resonator 30 (e.g., above the regulated level when a living being is present), or when the SOD 24C detects the approach of a living being, the controller 22 can be configured to reduce the power supply to the transmitter resonator 30 below the regulated level. The distance detector 24D is configured to determine the distance between the transmitter resonator 30 and the receiver resonator 50. The distance detector 24D can be implemented using a physical sensor (such as, without limitation, an optical sensor, an ultrasonic sensor, an infrared sensor, a proximity sensor, a radar, or a lidar) or by suitable software or firmware. For example, the distance detector 24D can be configured to determine the distance between the transmitter resonator 30 and the receiver resonator 50 based on changes in the transmitted power measured by the transmitter power sensor 24B. In one embodiment, one or more temperature sensors may monitor the temperature at the transmitter resonator 30 or the receiver resonator 50. If the temperature exceeds a predetermined limit, the controller 22 may cause the transmitter module 20 to reduce the proportion of power delivered by the IPT, reduce the total power feed to the transmitter resonator 30, or shut down power to the transmitter resonator 30 to prevent a fire hazard or thermal runaway. The oscillator 26A may be configured to control the frequency band and / or bandwidth and / or duty cycle (phase) (eg, 5% to 50%) of the current delivered to the transmitter resonator 30 in response to a signal from the controller 22 . A power amplifier 26B may be used to convert DC power into AC power. The power amplifier 26B may be used to adjust the power provided to the transmitter resonator 30 in response to a signal from the controller 22. In some embodiments, the controller 22 may send a signal to the power amplifier 26B to adjust the reflection coefficient of the power amplifier 26B. In some embodiments, the controller 22 may send a signal to the power amplifier 26B to turn off (or sleep) when the load detector 24A does not detect a load, or send a signal to turn on the power amplifier 26B when the load detector 24A detects a load. Power amplifier 26B may comprise a switched-mode power amplifier (in either single-ended or differential configuration) that can be configured to receive a square wave (sine wave) from oscillator 26A and generate a sine wave at a specific frequency desired to drive transmitter resonator 30. FIG8 is a schematic diagram of an exemplary power amplifier 26B that can be used in transmitter 30. Power amplifier 26B may be a differential switched-mode amplifier. Power amplifier 26B has three inputs: two input signals that drive active devices (transistors) 127C and 127D at a frequency set at the resonant frequency, and a DC voltage source 127E for controlling the output power and operating region of these active devices. Different load terminations are used to improve performance (e.g., output power, power conversion efficiency) and reduce unnecessary harmonic levels. In some embodiments, third harmonic termination 127F is located in the series branch to shape the voltage waveform at drain node 127G. Second harmonic termination 127H is located in the parallel branch to shape the voltage waveform at drain node 127G. First harmonic termination 127I is located in the series branch to shape the voltage waveform at drain node 127G. The effect of third harmonic termination can be accounted for in second harmonic termination 127H and first harmonic termination 127I. The effect of second harmonic termination 127H can be accounted for in first harmonic termination 127I. For the differential configuration of power amplifier 26B, AC load 127J (which receives the output power) is placed in series. The charging rate of AC load 127J can be a function of the alignment and position of transmitter resonator 30, receiver resonator 50, and / or the like. The power amplifier 26B may be configured to generate sufficient power for the transmitter resonator 30 so that an E field, or an H field, or any combination of E and H fields may be generated by the transmitter resonator 30 and captured by the receiver resonator 50 . Power amplifier 26B may include two phase shifters 127L in a differential configuration (but only one phase shifter in a single-ended configuration). Phase shifter 127L adjusts the appropriate phase difference between AC overload signal 127J and the gate signals of transistors 127C and 127D. The phase difference between the gate signals and AC overload signal 127J can change the performance of the power amplifier, such as the power conversion efficiency and operating region of the transistors. It can also change the output impedance of transistors 127C and 127D and / or the optimal AC load 127J of power amplifier 26B. Power amplifier 26B may include two level shifters 127K in a differential configuration (but only one level shifter in a single-ended configuration). Level shifter 127K can adjust the appropriate amplitude of the gate signals of transistors 127C and 127D. The amplitude level of the gate signals can change the performance of the amplifier (e.g., the power conversion efficiency and operating range of the transistors). Power amplifier 26B can be reconfigured to function as a rectifier, and in some embodiments, as a self-synchronous rectifier. As part of this reconfiguration, integrated phase shifter 127L and integrated level shifter 127K (see FIG8 ) can be adjusted based on the inherent amplification and switching capabilities of transistors 127C and 127D to allow power amplifier 26B to function as a rectifier. This reconfigurability of power amplifier 26B between operating as an amplifier and as a rectifier allows transmitter module 20 to be controllably reconfigured between transmitter mode and receiver mode, respectively. Reconfiguration can occur under instructions from controller 22. When power amplifier 26B reconfigures from an amplifier to a rectifier, AC load 127J changes to AC source 127J. Correspondingly, when power amplifier 26B reconfigures from an amplifier to a rectifier, DC source 127E reconfigures to a DC load. After explaining the secondary side 14 and its receiver module (both of which are shown in more detail in FIG. 7 ), the use of the transmitter module 20 in its receiver mode will be discussed below. The filter network 26C can adjust the frequency response, such as bandwidth, cutoff frequency, 3dB frequency, and gain provided to the transmitter resonator 30, in response to a signal from the controller 22. The filter network 26C can be configured to adjust the waveform shape of the power in the transmitter module 20 to increase the efficiency of the transmitter module 20. Matching network 26D may be configured to adjust impedance to match the output of power amplifier 26B to transmitter resonator 30 . A compensation network 26E may be provided to drive the transmitter resonator 30 at a desired resonant frequency (e.g., the resonant frequency of the receiver resonator), thereby increasing mutual flux, reducing heat generation, and improving power transfer efficiency. The compensation network 26E may include one or more capacitors for increasing capacitance and one or more inductors for increasing inductance. The compensation network 26E may be configured to increase capacitance (and / or decrease inductance) and increase inductance (and / or decrease capacitance) as desired. When the transfer mode ratio is 100% CPT, the compensation network 26E may function similarly to any known CPT compensation network (e.g., the compensation network 26E may function to increase inductance). Similarly, when the transfer mode ratio is 100% IPT, the compensation network 26E may function similarly to any known IPT compensation network (e.g., the compensation network 26E may function to increase capacitance). However, when the transmission mode is partial CPT and partial IPT, less compensation may be required because the capacitance of the transmitter resonator 30 will naturally compensate for the inductance of the transmitter resonator 30, and the inductance of the transmitter resonator 30 will naturally compensate for the capacitance of the transmitter resonator 30. For example, at approximately 50% IPT and 50% CPT (e.g., a transmission mode ratio equal to 1), the compensation network may not be required at all or its use may be substantially limited, thereby increasing the efficiency of the WPT system 10. As another example, between approximately 40% and 60% IPT and 40% and 60% CPT, no compensation network may be required or its use may be substantially limited, thereby increasing the efficiency of the WPT system 10. For this reason, the compensation network 26E may include fewer or smaller inductors and / or capacitors than in CPT WPT systems and / or pure IPT WPT systems, which require significant compensation. In certain embodiments, if the capacitance of the transmitter resonator 30 is significantly low, additional compensation may be provided by the compensation network 26E. Similarly, if the inductance of the transmitter resonator 30 is significantly low, additional compensation may be provided by the compensation network 26E. For example, the controller 22 may signal to the compensation network 26E how much and what type of compensation is required based on the transmit mode ratio, the distance between the transmitter resonator 30 and the receiver resonator 50, the amount of power drawn by the transmitter resonator 30, the power transmission efficiency, and the like. In some embodiments, the amount of compensation (e.g., capacitance increase or inductance increase) performed by compensation network 26E is proportional to the absolute value of the difference between the transfer mode ratio and 1. For example, if the transfer mode ratio is greater than 1, compensation network 26E may act to increase inductance, and the amount of inductance increase may increase as the transfer mode ratio increases above 1. Similarly, if the transfer mode ratio is less than 1, compensation network 26E may act to increase capacitance, and the amount of capacitance increase may increase as the transfer mode ratio decreases below 1. In certain embodiments, compensation network 26E can be configured to modulate the signal provided to transmitter resonator 30 with information, thereby acting as a source transmission modulator. The information used to modulate the signal provided to transmitter resonator 30 can be provided to compensation network 26E by controller 22. The information can include control data transmitted via receiver resonator 50 to controller 42 of receiver module 40. Controller 42 is described in more detail below with reference to FIG. 7 . In other embodiments, power amplifier 26B can act as the source transmission modulator. In yet further embodiments, oscillator 26A can act as the source transmission modulator. The modulation employed by the selected source transmission modulator can be any of amplitude modulation, frequency modulation, and phase modulation. The information can be modulated onto the signal provided to transmitter resonator 30 in digital or analog form. The information can be modulated by the source transmission modulator onto the resonant frequency of the power signal provided to transmitter resonator 30. In other embodiments, the information can be modulated onto a frequency different from the frequency of power transmission. In other embodiments, the information can be modulated onto a harmonic of the resonant frequency of the power signal provided to the transmitter resonator 30. In still further embodiments, the resonant frequency of the power signal provided to the transmitter resonator 30 can be a harmonic of the frequency of the signal onto which the information is modulated. The V / I tuner 26F, described in more detail below, can be configured to transmit an information signal to the transmitter resonator 30 while being transparent to the information being transmitted. The information transmitted in the manner described herein can include, without limitation, the operating mode of the module 20, the number and type of receiver modules 40, ambient object sensor information, and load status monitoring information including, for example, battery charge status, load voltage, and load current. FIG10 illustrates an embodiment of a V / I tuner 26F in greater detail. The input signal to the V / I tuner 26F, received from the matching network 26E (see FIG6 ), is split by a splitter 262 to provide two asymmetrical paths 261A and 261B for the input signal. A first phase shifter 264A and a second phase shifter 264B create a phase difference between the input voltage and the input current of the transmitter resonator 30 (see FIG6 ). The first phase shifter 264A is controlled by the controller 22 (see FIG6 ) via a first phase splitter control line 263A, while the second phase shifter 264B is controlled by the controller 22 (see FIG6 ) via a second phase splitter control line 263B. The first active switch 266A and the second active switch 266B receive signals from the first phase shifter 264A and the second phase shifter 264B, respectively, and are controlled by the controller 22 via the first active switch control line 265A and the second active switch control line 265B, respectively. The first active switch 266A and the second active switch 266B are used to adjust the imaginary components of the signals received from the first phase shifter 264A and the second phase shifter 264B, respectively. Passive signal shaping networks 268A and 268B receive the adjusted signals from the first active switch 266A and the second active switch 266B, respectively. The passive signal shaping networks 268A and 268B are used to fine-tune the signals received from the first active switch 266A and the second active switch 266B, respectively, and, in certain embodiments, to reduce any harmonics in these signals before passing them to the combiner 269. The signals provided along the two mutually asymmetric paths 261A and 261B are combined by the combiner 269 and provided to the transmitter resonator 30. In other embodiments, the first phase shifter 264A and the second phase shifter 264B may be combined into one phase shifter that receives the input signal to the V / I tuner 26F, and the combined phase shifter may have two separate outputs that serve the active switches 266A and 266B. The V / I tuner 26F adjusts the transmit mode ratio by adjusting the phase difference between the input current and the input voltage of the transmitter resonator 30 in response to a signal from the controller 22. The real part of the impedance seen by the transmitter module 20 is adjusted by phase shifters 264A and 264B, and its imaginary part can be adjusted by switches 266A and 266B. For example, a 90-degree phase shift every 3 milliseconds out of every 10 milliseconds can result in 30% magnetic force transmission and 70% electrical power transmission. The V / I tuner 26F may be configured to adjust the current passing through and the potential applied to each transmitter antenna (e.g., the first transmitter antenna 32, 132, 232, 332 and the second transmitter antenna 134, 234, 334 or the third transmitter antenna 336). If current is passed through both the first and second transmitter antennas 132, 134, they each generate a magnetic field 31A for IPT purposes. If the current delivered to the second transmitter antenna 134 is reduced compared to the current delivered to the first transmitter antenna 132, a potential difference is created between the first and second transmitter antennas 132, 134, and an electric field 31B is generated for CPT purposes. To switch between CPT and IPT, the current delivered to the second antenna 134 can be modulated (e.g., when less current is allowed to pass through the second antenna 134, less IPT will occur, and when more current is allowed to pass through the second antenna, more CPT will occur). For example, when it is desired to transmit power via IPT, the I / V tuner 26F can be configured to act as a short circuit connecting the first and second transmitter antennas together, thereby forming a series LC resonator that allows current to flow therethrough. Conversely, when it is desired to transmit power via the CPT, the I / V tuner 26F can be configured to act as an open circuit to dump current, thereby creating a potential difference between the first and second transmitter antennas. The I / V tuner 26F can thereby be configured to control whether the first and second transmitter antennas 132, 134 are effectively connected in series or in parallel. Alternatively, when the first and second transmitter antennas 132 and 134 are connected in parallel, the first and second transmitter antennas 132 and 134 can be floating to generate an electric field 31B for CPT purposes without substantially generating a magnetic field 31A. To change the transmit mode ratio (e.g., to modulate between CPT and IPT), the I / V tuner 26F can be configured (via a multiplexer of the I / V tuner 26F, etc.) to alternate between: (1) floating the first and second transmitter antennas 132 and 134 to induce CPT; and (2) driving current through the first and second transmitter antennas 132 and 134 to induce IPT. The alternation can be performed within milliseconds or at a frequency between 10 Hz and 10 kHz. With more time allocated to floating the first and second transmitter antennas 132, 134, the transmit mode ratio will be biased toward achieving more CPT, and with more time allocated to driving current through the first and second transmitter antennas 132, 134, the transmit mode ratio will be biased toward achieving more IPT. In some embodiments, components 26 may be discrete components in transmitter module 20 , while in other embodiments, one or more of components 26 may be part of an integrated circuit design. FIG. 7 is a schematic depiction of a load 70 and the secondary side 14 (as shown in FIG. 1 ) including the receiver resonator 50 and the receiver module 40 , according to certain embodiments. The receiver resonator 50 may include any of the receiver resonators 50, 150, 250, 350, or other receiver resonators described herein. The receiver resonator 50 may be configured to capture power at a frequency set by the oscillation signal in the transmitter module 20 (e.g., without limitation, such as between 1 MHz and 1 GHz).In some embodiments, the frequency set by the oscillation signal in the transmitter module 20 is about 1 MHz to about 100 MHz, about 1 MHz to about 200 MHz, about 1 MHz to about 300 MHz, about 1 MHz to about 400 MHz, about 1 MHz to about 500 MHz, about 1 MHz to about 600 MHz, about 1 MHz to about 700 MHz, about 1 MHz to about 800 MHz, about 1 MHz to about 900 MHz, about 1 MHz to about 1 GHz, about 100 MHz to about 200 MHz, about 100 MHz to about 300 MHz, about 100 MHz to about 400 MHz, about 100 MHz to about 500 MHz, about 100 MHz to about 600 MHz, about 100 MHz to about 700 MHz, about 100 MHz to about 800 MHz, about 100 MHz to about 900 MHz, about 1 MHz to about 1 GHz, about 200 MHz to about 300 MHz, about 200 MHz to about 400 MHz, about 200 MHz to about 500 MHz, about 200 MHz to about 600 MHz, about 200 MHz to about 700 MHz, about 200 MHz to about 800 MHz, about 200 MHz to about 900 MHz, about 200 MHz to about 1 GHz, about 300 MHz to about 400 MHz, about 300 MHz to about 500 MHz, about 300 MHz to about 600 MHz, about 300 MHz to about 700 MHz, about 300 MHz to about 800 MHz, about 300 MHz to about 900 MHz, about 300 MHz to about 1 GHz, about 400 MHz to about 500 MHz, about 400 MHz to about 600 MHz, about 400 MHz to about 700 MHz, about 400 MHz to about 800 MHz, about 400 MHz to about 900 MHz, about 400 MHz to about 1 GHz, about 500 MHz to about 600 MHz, about 500 MHz to about 700 MHz, about 500 MHz to about 800 MHz, about 500 MHz to about 900 MHz, about 500 MHz to about 1 GHz, about 600 MHz to about 700 MHz, about 600 MHz to about 800 MHz, about 600 MHz to about 900 MHz, about 600 MHz to about 1 GHz, about 700 MHz to about 800 MHz, about 700 MHz to about 900 MHz, about 700 MHz to about 1 GHz, about 800 MHz to about 900 MHz, about 800 MHz to about 1 GHz, or about 900 MHz to about 1 GHz.In some embodiments, the frequency set by the oscillation signal in the transmitter module 20 is about 1 MHz, about 100 MHz, about 200 MHz, about 300 MHz, about 400 MHz, about 500 MHz, about 600 MHz, about 700 MHz, about 800 MHz, about 900 MHz, or about 1 GHz. In some embodiments, the frequency set by the oscillation signal in the transmitter module 20 is at least about 1 MHz, about 100 MHz, about 200 MHz, about 300 MHz, about 400 MHz, about 500 MHz, about 600 MHz, about 700 MHz, about 800 MHz, or about 900 MHz. In some embodiments, the frequency set by the oscillation signal in transmitter module 20 is at most about 100 MHz, about 200 MHz, about 300 MHz, about 400 MHz, about 500 MHz, about 600 MHz, about 700 MHz, about 800 MHz, about 900 MHz, or about 1 GHz. For some applications, frequencies in the Industrial, Scientific, and Medical (ISM) band may be preferred. For the purposes of this invention, the ISM band is understood to be 6.765 MHz to 6.795 MHz; 13.553 MHz to 13.567 MHz; 26.957 MHz to 27.283 MHz; 40.66 MHz to 40.70 MHz; 83.996 MHz to 84.004 MHz; 167.992 MHz to 168.008 MHz; 433.05 MHz to 434.79 MHz; and 886 MHz to 906 MHz. For other applications, frequencies in officially reserved application bands may be preferred, such as, without limitation, police communications or military bands. Receiver resonator 50 may be configured to capture power at that frequency from magnetic field 31A or electric field 31B, or any combination of the two fields. Receiver module 40 includes a controller 42. Controller 42 is configured to receive various inputs from sensors 44 (e.g., receiver power sensor 44A and load detector 44B) and output control signals to various components 46 (e.g., compensation network 46A, matching network 46B, rectifier 46D, filter 46C, and load manager 46E). The receiver power sensor 44A may measure the power at point 44C (eg, measure current and voltage) to determine how much power the receiver resonator 50 is receiving. Load detector 44B is configured to detect the presence of load 70. Load detector 44B can be implemented using a physical sensor (such as, without limitation, an optical sensor, a pressure sensor, an infrared sensor, or a proximity sensor) or with the aid of suitable software or firmware. For example, in some embodiments, load detector 44B measures the current and voltage at, for example, point 44D to determine the power being received by load 70. If the amount of power measured at point 44D increases above a baseline, load detector 44B signals controller 42 that load 70 is present. The compensation network 46A can be configured to maintain a desired resonant frequency of the receiver resonator 50 in response to a signal from the controller 42, thereby improving the efficiency of power transfer from the transmitter resonator 30 to the receiver resonator 50. The compensation network 46A can be similar to the compensation network 26E of the transmitter module 20 and can function substantially the same as the compensation network 26E of the transmitter module 20. The matching network 26D may be configured to adjust the input impedance of the rectifier 46D to match the desired impedance of the transmitter resonator 30 to achieve maximum power transfer. The rectifier 46D may be configured to convert AC power received by the receiver antenna 50 into DC power to be provided to the load 70 . The filter 46C may be configured to shape the waveform of the power output from the rectifier 46D according to a signal from the controller 42 , so as to improve the overall power efficiency of the receiver module 40 . Load manager 46E may be configured to provide appropriate voltage and current to load 70 and / or extract maximum power from rectifier 46D by adjusting its input impedance (eg, output impedance of rectifier 46D). In certain embodiments, load manager 46E or another component can be configured to communicate (wirelessly or wired) with an external device (e.g., load 70) to provide appropriate information for data analysis. For example, and without limitation, this information may include: the presence of load 70, the charge level of load 70, the charge rate of load 70, the status of load 70, the current voltage, capacity, and / or the remaining time to charge load 70. Load manager 46E can use this information (or relay it to controller 42 or controller 22) to adjust, for example, the transfer mode ratio to achieve optimal energy transfer between primary side 12 and secondary side 14. Load manager 46E can also provide this information to a user via a display. This display can be built into one or more of primary side 12 and secondary side 14 or accessible via software on a mobile device (e.g., an application on a mobile phone or tablet in wireless (or wired) communication with load manager 46E or controller 22 or controller 42). In some embodiments, components 46 are discrete components within receiver module 40, while in other embodiments, one or more of components 46 are part of an integrated circuit design. In some embodiments, the primary side 12 may include a plurality of transmitter resonators 30, and / or the secondary side 14 may include a plurality of receiver resonators 50. In such embodiments, each of the transmitter resonators 30 and / or receiver resonators 50 may be controlled in a similar manner. In other embodiments, each of the transmitter resonators 30 and / or receiver resonators 50 may be controlled individually. For example, in some embodiments, the primary side 12 may rely more heavily on transmitter resonators 30 that experience less interference (e.g., due to nearby metal objects), are not in the vicinity of living beings, or transmit power more efficiently and / or similarly, and the secondary side 14 may rely more heavily on receiver resonators 50 that experience less interference (e.g., due to nearby metal objects), are not in the vicinity of living beings, or receive power more efficiently. For example, this control may be provided or facilitated by the transmitter module 20 and the receiver module 40 and / or communication therebetween. 9 is a schematic depiction of a rectifier 46D having integrated phase shifters. In certain embodiments, the rectifier 46D includes discrete phase shifters. The rectifier 46D can be a switched-mode self-synchronous rectifier (in single-ended mode or differential configuration) that can be configured to receive a sine wave (e.g., AC power) at a specific resonant frequency from the receiver resonator 50. The rectifier 46D can be a differential switched-mode self-synchronous rectifier. The rectifier 46D can capture enough power from the receiver resonator 50 so that the E field, the H field, or any combination of the E field and the H field can be captured by the receiver resonator 50. Rectifier 46D has an input 147A (e.g., AC power) that drives an active device 147B (e.g., a transistor) at a frequency set at the resonant frequency, and an output 147D (e.g., a DC voltage) across a DC load (used to control the active device's output power, input impedance, and operating region). In this design, different load terminations are used to improve performance (e.g., output power and power conversion efficiency). Third harmonic termination 147D is located in the series branch to shape the voltage waveform at drain node 147E. Second harmonic termination 147F is located in the parallel branch to shape the voltage waveform at drain node 147E. First harmonic termination 147G is located in the series branch to shape the voltage waveform at drain node 147E. The effect of third harmonic termination 147D can be accounted for in second harmonic termination 147F and first harmonic termination 147G. The effect of second harmonic termination 147F can be accounted for in first harmonic termination 147G. For the differential configuration, the AC source 147A is placed in series. The AC source 147A may be a function of the power received by the receiver resonator 50 and the alignment and position of the receiver resonator 50 relative to the transmitter resonator 30. The DC load 147C may be a single-ended load. Rectifier 46D may include two phase shifters 147H in a differential configuration (but only one phase shifter in a single-ended configuration). Phase shifter 147H adjusts the appropriate phase difference between the AC source and the gate signal of transistor 147B. The phase difference between the gate signal and AC source 147A can change the performance of the self-synchronous rectifier (e.g., the transistor's power conversion efficiency and operating region). It can also change the input impedance of self-synchronous rectifier 46D and / or the optimal DC load 147C of rectifier 46D. Rectifier 46D can include two level shifters 147I in a differential configuration (but only one level shifter in a single-ended configuration). Level shifter 147I can adjust the appropriate amplitude of the gate signal of transistor 147B. The amplitude level of the gate signal can change the performance of the self-synchronous rectifier (e.g., the power conversion efficiency and operating region of the transistor). Rectifier 46D can be reconfigured to function as an amplifier. As part of this reconfiguration, integrated phase shifter 147H and integrated level shifter 147I (see FIG. 9 ) can be adjusted to allow rectifier 46D to function as an amplifier based on the inherent amplification and switching capabilities of transistor 147B. This reconfigurability of rectifier 46D between operating as a rectifier and operating as an amplifier allows receiver module 40 to be controllably reconfigured between receiver mode and transmitter mode, respectively. Reconfiguration can occur under instructions from controller 42. When rectifier 46D is reconfigured from a rectifier to an amplifier, AC source 147A changes to AC load 147A. Correspondingly, when rectifier 46D is reconfigured from a rectifier to an amplifier, DC load 147C is reconfigured to a DC source. In certain embodiments, when the receiver module 40 is in transmitter mode, the compensation network 46A can be configured to modulate the signal provided to the resonator 50 with information, thereby acting as a source transmission modulator. The information used to modulate the signal provided to the resonator 50 can be provided to the compensation network 46A by the controller 42. The information can include control data transmitted via the transmitter resonator 30 to the controller 22 of the transmitter module 20. In certain embodiments, when the receiver module 40 is in transmitter mode and the rectifier 46D is configured as an amplifier, the amplifier 46D can act as a modulator for the receiver module 40. The modulation employed can be any of amplitude modulation, frequency modulation, phase modulation, and combinations thereof. The information can be modulated onto the signal provided to the transmitter resonator 50 in digital or analog form. The information can be modulated onto the resonant frequency of the power signal provided to the transmitter resonator 50 by the source transmission modulator. In other embodiments, the information can be modulated onto a frequency different from the frequency of power transmission. In other embodiments, the information may be modulated onto a harmonic of the resonant frequency of the power signal provided to the transmitter resonator 50. In still further embodiments, the resonant frequency of the power signal provided to the transmitter resonator 50 may be a harmonic of the frequency of the signal onto which the information is modulated. For example, and without limitation, the information transmitted in the manner described herein may include: the presence of the load 70, the charge level of the load 70, the power transfer efficiency, the charging rate of the load 70, the status of the load 70, the current voltage, the charge capacity, and the remaining time to charge the load 70. Having described above how both transmitter module 20 and receiver module 40 can be reconfigured between operating in transmitter mode and operating in receiver mode, and having described how signals from both transmitter module 20 and receiver module 40 can be modulated, it is apparent that system 10 of FIG1 can function as a full-duplex transmit-receive system for transmitting information in both directions via resonators 30 and 50. System 10 of FIG1 can include additional secondary sides similar to secondary side 14 of FIG1 and FIG7. When additional secondary sides are present, the configuration described above allows information to be transferred between the respective secondary sides. In some embodiments, the primary side 12 and the secondary side 14 can communicate via Bluetooth (e.g., 2.4 GHz) or a signal frequency similar to that of GPS (e.g., 10 GHz). In some embodiments, there may be an additional unit that can separately collect data and transmit data back and forth between the primary side 12 and / or the secondary side 14. In some embodiments, WiFi can be used to upload data from the primary side 12 and / or the secondary side 14 to an online portal (e.g., a website or mobile application associated with the primary side 12 and / or the secondary side 14). In certain embodiments, it may be desirable to transfer power between two receiver modules 40 (e.g., peer-to-peer power transfer). For example, if a first electric bicycle with a first receiver is dead or low on power, and a second electric bicycle with a second receiver and an at least partially charged battery is nearby, it may be desirable to transfer power from the second electric bicycle to the first electric bicycle. This situation may involve, for example, when there is no transmitter nearby. The facility of reconfiguring at least one of the two receiver modules 40 involved in the configuration as a transmitter module enables this peer-to-peer power transfer. Generally speaking, this enables the forwarding of power between multiple secondary sides 14. In other embodiments, it may be necessary to transfer power in the reverse direction (i.e., from the load side to the source side of Figures 1, 6, and 7) at specific times. The ability of both transmitter module 20 and receiver module 40 to reconfigure between operating in transmitter mode and receiver mode allows for such power transfer in the "reverse" direction from receiver module 40 to transmitter module 20. The system thus allows for bidirectional power transfer. Given that device 26B of Figure 8 and device 46D of Figure 9 can be reconfigured to function as an amplifier or rectifier, respectively, these devices may be collectively referred to as "differential self-synchronous RF power amplifier / rectifiers." Given the bidirectional nature of power transfer, both transmitter resonator 30 and receiver resonator 50 may be described as "transmitter-receiver resonators," and both transmitter module 20 and receiver module 40 may be referred to as "power transmitter-receiver modules." Such configurations are useful in electric vehicles, where kinetic energy is converted during braking and needs to be transferred to the battery. For example, and without limitation, such redirected power transfer is applicable to other systems, situations, and arrangements where several mobile phones may have different levels of remaining battery charge, and such an arrangement may be used to at least partially recharge another mobile phone. More generally, when neither the transmitting system nor the receiving system has a permanent energy source (e.g., a power grid), then bidirectional functionality may be employed to transfer energy in either direction. In another embodiment described with respect to FIG. 31 , a near-field RF method

[2200] for transmitting power via a power signal at a power signal frequency is provided, the method comprising: providing

[2210] a dual-peak resonant near-field RF power transfer system comprising a plurality of power transmit-receive modules, wherein each of the plurality of power transmit-receive modules is in wired communication with a transmitter-receiver resonator configured to exchange power with at least another transmit-receive module of the plurality of power transmit-receive modules; and operating

[2220] the power transfer system according to an adjustable transfer mode ratio for simultaneous capacitive power transfer and inductive power transfer. Providing

[2210] a power transmission system may include providing a first power transmission-reception module having a power signal tuner module among a plurality of power transmission-reception modules, and operating

[2220] the power transmission system may include changing the transmission mode ratio by adjusting the power signal tuner module. Providing

[2210] a power transmission system may include providing at least one power transmission-receive module in wired communication with an associated transmitter-receiver resonator and having a modulator among a plurality of power transmission-receive modules, and operating

[2220] the power transmission system may include: exchanging radio frequency signals between the associated transmitter-receiver resonator and a transmitter-receiver resonator in wired communication with at least another power transmission-receive module among the plurality of power transmission-receive modules; and modulating information onto the exchanged radio frequency signals. When a power load is present at the output of one of the plurality of power transmission-receive modules, for example, without limitation, the information modulated on the exchanged signals may include: one or more of: the presence of the power load, the charge level of the power load, the power transmission efficiency, the charging rate of the power load, the state of the power load, the presence of a voltage across the power load, the charge capacity of the power load, and the remaining time to charge the power load. The information may be modulated onto the exchanged radio frequency signal by amplitude modulation, frequency modulation, or phase modulation. Modulating the information onto the exchanged radio frequency signal may include modulating digital information or analog information onto the exchanged radio frequency signal. Modulating the information onto the exchanged radio frequency signal may include modulating the information onto the power signal. Modulating the information onto the exchanged radio frequency signal may include modulating the information onto a signal having a frequency different from the power signal frequency. Modulating the information onto the exchanged radio frequency signal may include modulating the information onto a signal having a frequency that is a harmonic of the power signal frequency. Modulating the information onto the exchanged radio frequency signal may include modulating the information onto a signal having the power signal frequency as a harmonic. Modulating information onto the exchanged radio frequency signals may include modulating reflection characteristics of associated wired transmitter-receiver resonators according to the information to impose the information on signals reflected by the wired transmitter-receiver resonators. Modulating information onto the exchanged radio frequency signals may include modulating signals provided to the associated transmitter-receiver resonators according to the information. The method

[2200] may include operating a power signal tuner module of a first power transmit-receive module of a plurality of power transmit-receive modules to modulate information onto an exchanged radio frequency signal. Each of the provided power transmit-receive modules may include a compensation network, and the compensation network may include a modulator, thereby allowing the compensation network to be operated to modulate information onto the exchanged radio frequency signal. At least one of the power transmit-receive modules may include a radio frequency oscillator that provides a signal at a power signal frequency to the at least one power transmit-receive module, and the radio frequency oscillator may include a modulator, thereby allowing the information to be modulated in the oscillator onto the exchanged radio frequency signal. Each of the plurality of power transmit-receive modules provided may be reconfigurable between a power transmitter mode and a power receiver mode; and the method may further include reconfiguring at least two of the plurality of power transmit-receive modules between the power transmitter mode and the power receiver mode to reverse the direction of power transmission between the at least two transmit-receive modules. Each of the power transmit-receive modules provided may include a differential self-synchronous RF power amplifier / rectifier capable of reconfiguring between an amplifier state and a rectifier state corresponding to the power transmitter mode and the power receiver mode of the power transmit-receive module, respectively; and the method may include reconfiguring the differential self-synchronous RF power amplifier / rectifier of the at least two transmit-receive modules between the amplifier state and the rectifier state. Each differential self-synchronous RF power amplifier / rectifier may include a phase shifter that is adjustable for reconfiguring the differential self-synchronous RF power amplifier / rectifier between an amplifier state and a rectifier state; and the method may include adjusting the phase shifter of each of the differential self-synchronous RF power amplifiers / rectifiers in the at least two transmit-receive modules. The WPT system 10 including the transmitter and / or receiver described herein can be integrated into various applications, such as, but not limited to, electric vehicles, electric boats, electric airplanes, electric trucks, electric bicycles, electric motorcycles, electric skateboards, etc. An exemplary non-limiting application is a shared bike fleet, where various portable computer docks are provided that integrate one or more transmitters (e.g., primary side 12), and electric bicycles including receivers (e.g., secondary side 14) and batteries (as loads 70) can be charged at the portable computer docks. In some applications, the primary side 12 or the secondary side 14 can be configured to transfer power using other systems not described herein, and the transfer mode ratio can be adjusted from CPT to IPT to provide compatibility with other CPT systems and / or IPT systems, even if the other systems are not specifically designed to work with the power transfer system described herein. While several exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain modifications, permutations, additions, and sub-combinations thereof. It is therefore intended that the following appended claims and hereafter incorporated claims be interpreted to include all such modifications, permutations, additions, and sub-combinations consistent with the broadest interpretation of this specification as a whole. In a first aspect, each of the systems described above and depicted in FIG. 1 to FIG. 10 forms a dual-peak near-field resonant wireless power transfer system 10 configured for simultaneously performing capacitive power transfer and inductive power transfer according to an adjustable transfer mode ratio at a variable resonant power signal oscillation frequency. The system 10 includes: a transmitter subsystem 12 including a transmitter antenna subsystem 32, 132, 232, 332, 134, 234, 334, 336 and a power signal tuner module 26F; a tuner module 26F; and a power signal tuner module 26F. 6F is configured to adjust the transmit mode ratio by adjusting the power signal provided by the tuner module 26F to the transmitter antenna subsystem 32, 132, 232, 332, 134, 234, 334, 336; and the receiver subsystem 14 includes a receiver antenna subsystem 52, 152, 252, 352, 154, 254, 354, 356 configured to receive power from the transmitter antenna subsystem 32, 132, 232, 332, 134, 234, 334, 336 according to the transmit mode ratio. The tuner module 26F may be configured to adjust the power signal by adjusting the phase difference between the current and the voltage of the power signal provided to the transmitter antenna subsystem 32, 132, 232, 332, 134, 234, 334, 336. The transmitter subsystem 12 may further include a controller 22 and at least one sensor 24, wherein the controller 22 is configured to receive sensor information from the at least one sensor 24 and automatically provide tuning instructions to the tuner module 26F based on the sensor information, and the tuner module 26F is configured to adjust the phase difference between the current and the voltage of the power signal provided to the transmitter antenna subsystem 32, 132, 232, 332, 134, 234, 334, 336 according to the tuning instructions. System 10 resonates at a resonant frequency that can vary freely within a predetermined frequency band based on the degree of coupling between transmitter subsystem 12 and receiver subsystem 14. For example, and without limitation, the predetermined frequency band may be the officially designated and reserved Industrial, Scientific, and Medical (ISM) band or a user-specific frequency band. The quality factor (Q) of system 10 can be reduced to a level that allows the power signal oscillation frequency to vary within the opposite extremes of the predetermined frequency band. The reduced Q value allows system 10 to adopt any of several different resonant frequencies within the predetermined frequency band during the power transfer process. The coupling between transmitter subsystem 12 and receiver subsystem 14 and the associated power absorption of resonant receiver subsystem 14 ensure that less electromagnetic radiation is emitted into the far-field domain when system 10 is in operation. The arrangement described herein with reference to FIGURES 1-10, along with the frequency profiles immediately described above, makes system 10 a dual-peak near-field resonant wireless power transfer system. It should be noted that in the wireless power transfer system 10 , power is transferred from the primary subsystem to the secondary subsystem via capacitive coupling or inductive coupling, or both, rather than to any substantial extent via electromagnetic radiation. In another embodiment described with reference to the aforementioned figures and the flowchart in FIG11 , a near-field wireless method

[1000] for bimodally transmitting power according to an adjustable transmission mode ratio at a variable resonant power signal oscillation frequency is provided, the method comprising: providing

[1010] a transmitter subsystem 12 comprising a power signal tuner module 26F and a transmitter antenna subsystem 32, 132, 232, 332, 134, 234, 334, 336 configured to resonate at the resonant power signal oscillation frequency; providing

[1020] a receiver antenna subsystem 52, 152, 252, 352, 154, 254, 354, 356 configured to resonate at the resonant power signal oscillation frequency. a receiver subsystem 14; providing

[1030] a power signal from the tuner module 26F to the transmitter antenna subsystems 32, 132, 232, 332, 134, 234, 334, 336 at a power signal oscillation resonant frequency; adjusting

[1040] the transmission mode ratio by adjusting the power signal from the tuner module 26F to the transmitter antenna subsystems 32, 132, 232, 332, 134, 234, 334, 336; and receiving

[1050] the transmitted power according to the transmission mode ratio via the receiver antenna subsystems 52, 152, 252, 352, 154, 254, 354, 356 at the power signal oscillation resonant frequency in the receiver subsystem 14. Adjusting

[1040] the transmit mode ratio may include adjusting a phase difference between a current and a voltage of a power signal provided to the transmitter antenna subsystem 32, 132, 232, 332, 134, 234, 334, 336. The transmitter subsystem 12 may further include a controller 22 and at least one sensor 24, and the phase difference between the current and the voltage may be adjusted by a tuner module 26F based on sensor information received by the controller 22 from the at least one sensor 24 via a command from the controller 22. The controller 22 may automatically send a command from the controller 22 to the tuner module 26F when the controller 22 receives the sensor information; and the tuner module 26F may automatically execute the command from the controller 22 to change the phase difference. The method

[1000] may further include allowing

[1060] the resonant power signal oscillation frequency to vary within a predetermined frequency band. The predetermined frequency band may be an industrial, scientific, and medical (ISM) band. Providing

[1010] the transmitter subsystem may include providing the transmitter subsystem with demodulation to a degree that allows the resonant power signal oscillation frequency to vary within opposite extremes of the predetermined frequency band. In yet another embodiment, described with reference to Figures 12, 13A, and 13B, and with reference to Figures 1 through 10, a multi-transmitter dual-peak near-field resonant wireless power transfer system 10′ is configured for simultaneous capacitive and inductive power transfer at a variable resonant power signal oscillation frequency with an adjustable transmit mode ratio. System 10′ includes a multi-transmitter subsystem 12′, which includes a plurality of transmitter resonators 30A′ through 30I′, each driven by a corresponding dedicated transmitter module 20A′ through 20I′. Each transmitter resonator and corresponding transmit module (e.g., 30E′ and 20E′, respectively) can be consistent with the description set forth above with reference to Figures 1 through 10. Figure 12 is a schematic representation of an embodiment of system 10′, in which transmitter resonators 30A′ through 30I′ are presented as nine resonators in a row but are not depicted in their formalized spatial positions. An embodiment of the spatial layout of multi-transmitter subsystem 12′ is shown in Figures 13A and 13B and described below. In system 10′, the resonant receiver subsystem 14 can be the same as or substantially similar to the resonant receiver system described above and referenced in Figures 1-10. In the embodiment shown in Figure 12, the resonant receiver subsystem 14 can be implemented in a mobile phone or digital "tablet," for example, without limitation. For clarity, the resonant receiver subsystem 14 is depicted in broken outline in Figure 13A. In an embodiment, each active transmitter resonator 30A′-30I′ and each corresponding transmitter module 20A′-20I′ can function the same as or substantially similar to the transmitter resonator 30 and transmitter module 20 described above and shown in Figures 1-10. An embodiment of a spatial layout of the multiple transmitter subsystem 12′ is illustrated in Figures 13A and 13B. Figure 13B shows the multiple transmitter subsystem 12′ in an opposite orientation relative to its orientation in Figure 13A. In the exemplary embodiment of system 10′ shown in Figures 12, 13A, and 13B, multi-transmitter subsystem 12′ includes nine pairs of transmitter resonators 30A′-30I′ and corresponding transmitter modules 20A′-20I′ arranged in a square array. Transmitter modules 20A′-20I′ are obscured by grounded substrate 35′ in Figure 13A but can be seen in Figure 13B. In more general embodiments, other numbers of pairs of resonators and transmitter modules may be employed, and the resonator array need not be square or rectangular. By way of example and not limitation, the resonator array may have a hexagonal arrangement. In certain embodiments, it is preferable to tightly pack the arrays within the confines of a grounded shielding mesh that separates and defines the transmitter resonators 30A′-30I′. The grounded shielding mesh 33′ laterally confines the array of transmitter resonators 30A′-30I′. The ground shield mesh 33′ is disposed at a consistent distance 37′ from the perimeter of each of the transmitter resonators 30A′- 30I′ to ensure consistent electric field behavior and associated capacitance between the transmitter resonators 30A′- 30I′ and the ground shield mesh 33′. The term “shielding distance” is used herein to describe this distance between the transmitter resonators 30A′- 30I′ and the ground shield mesh 33′. In one embodiment, the grounded shield mesh 33' ensures that the electric fields of the transmitter resonators 30A' to 30I' are completely spatially decoupled and thereby spatially independent. The transmitter resonators 30A' to 30I' may have magnetic fields that are selected to be decoupled from each other by virtue of their spatial positioning. In other embodiments, the grounded shield mesh 33' may be formed of or coated with a highly conductive ferrite material to decouple the magnetic fields generated by the transmitter resonators 30A' to 30I'. As shown in Figures 13A and 13B, transmitter resonators 30A'-30I' and their corresponding transmitter modules 20A'-20I' can be mounted substantially in rows on opposite sides of a grounded substrate 35', with each transmitter resonator (e.g., 30E') proximate its corresponding transmitter module (20E'). In other embodiments, there may not be a fixed spatial relationship between a transmitter resonator and its corresponding transmitter module. The array of transmitter resonators 30A'-30I' shares a common emitting surface defined by the collective upper surface of the transmitter resonators 30A'-30I' in Figure 13A. For aesthetic and protective reasons, the array of transmitter resonators 30A'-30I' can be covered with a dielectric plate (not shown in Figure 13A). The dielectric plate separates the receiver subsystem 14 from the transmitter resonators 30A'-30I'. In Figures 12 and 13A, an embodiment of a resonant receiver subsystem 14 is schematically shown overlapping a subset of a plurality of transmitter resonators 30A'-30I'. According to Figures 12 and 13A, the overlapping transmitter resonators are shown as 30D', 30E', ​​30G', and 30H'. In Figure 13A, the resonant receiver subsystem 14 is shown as a dotted rectangle above the mutually adjacent transmitter resonators 30D', 30E', ​​30G', and 30H'. The controller of any of the transmitter modules 20A'-20I' can determine the presence or absence of a resonant receiver subsystem 14 proximate to or overlapping its corresponding transmitter resonator 30A'-30I' and, based on such detection, can turn the power signal to its corresponding transmitter resonator 30A'-30I' on or off. If the power amplifiers of the transmitter modules 20A′ to 20I′ supply power signals to the transmitter resonators 30A′ to 30I′, causing the transmitter resonators 30A′ to 30I′ to transmit power, and the controllers of the transmitter modules 20A′, 20B′, 20C′, 20F′, and 20I′ determine that there are no resonant receivers within their frequency ranges close to the transmitter resonators 30A′, 30B′, 30C′, 30F′, and 30I′, then those controllers may shut off the power signals to the transmitter resonators 30A′, 30B′, 30C′, 30F′, and 30I′. If the power amplifiers of transmitter modules 20A′ to 20I′ do not supply power signals to transmitter resonators 30A′ to 30I′, the controllers for transmitter resonators 30D′, 30E′, 30G′, and 30H′ can determine the presence of a resonant receiver subsystem 14 that overlaps with and is proximate to resonators 30D′, 30E′, 30G′, and 30H′ and turn on the transmittable power provided by transmitter modules 20D′, 20E′, 20G′, and 20H′ to transmitter resonators 30D′, 30E′, 30G′, and 30H′. This configuration ensures that only transmitter resonators proximate to the resonant receiver subsystem 14 are drawing power and transmitting power to the resonant receiver subsystem 14. The input impedance of transmitter resonators 30A′ to 30I′ can be used to detect the presence or absence of a resonant receiver subsystem 14 in proximity to the transmitter resonator. The transmitter resonator input impedance varies depending on the presence or absence of a resonant receiver subsystem 14 in proximity to the transmitter resonator. As described above, with reference to FIG6 , the impact of a particular resonant receiver subsystem 14 is different, allowing not only the presence or absence of a receiver to be detected, but also the detection of characteristics that allow the type of receiver to be identified by its impact on the transmitter resonator input impedance. In certain embodiments, the size of the receiver resonator has a significant impact on the input impedance of transmitter resonators 30A′ to 30I′. In an embodiment of the system 10′, the transmitter module 20E′ shown in FIG12 and FIG13B is a transmitter module associated with one of the four transmitter resonators 30D′, 30E′, 30G′, and 30H′ overlapped by the resonant receiver subsystem 14. The detailed structure of each of the transmitter modules 20A′ to 20I′ is provided in FIG6 and FIG8. The process is started without the power amplifier 26B of the transmitter module 20A′ to 20I′ providing a power signal to the corresponding transmitter resonator 30A′ to 30I′. Now focusing on transmitter module 20E′, in this embodiment, its load detector 24A is configured to measure the input impedance of transmitter resonator 30E′. Load detector 24A provides the input impedance measurement to controller 22. A default input impedance measurement value is stored in a register within controller 22. This default input impedance measurement value represents the input impedance of transmitter resonator 30E′ in the absence of any resonant receiver subsystem in close proximity to transmitter resonator 30E′. As shown in FIG12 , placing resonant receiver subsystem 14 in close proximity to transmitter resonator 30E′ results in a new, different input impedance measurement being taken by load detector 24A, the result of which is provided by load detector 24A to controller 22. Controller 22 compares the new input impedance measurement (referred to herein as the "first input transmitter resonator impedance change" or "main transmitter resonator input impedance change") to the default impedance measurement value stored in the register. Based on this first input impedance change, the controller 22 makes a determination as to whether a receiver resonator (e.g., a resonator of the resonant receiver subsystem 14) is present proximate to the transmitter resonator 30E′. To make this determination as to the presence or absence of a receiver resonator proximate to the transmitter resonator 30E′, the controller 22 may be pre-programmed with a minimum input impedance change that must be exceeded before the controller 22 deems a receiver resonator present. If the controller 22 determines that a receiver resonator (e.g., a resonator of the resonant receiver subsystem 14) is present in proximity to the transmitter resonator 30E′, the controller 22 instructs the power amplifier to assume an "on" state. This provides power to the transmitter resonator 30E′ and, in turn, transfers power to the resonant receiver subsystem 14. If the controller 22 determines that no receiver resonator (e.g., a resonator of the resonant receiver subsystem 14) is present in proximity to the transmitter resonator 30E′, the controller 22 instructs the power amplifier to assume an "off" state. This provides no power to the transmitter resonator 30E′ and, in turn, transfers no power to the resonant receiver subsystem 14. The same process is independently performed by each transmitter module 20A′-20I′ with respect to its corresponding transmitter resonator 30A′-30I′. Thus, the power amplifiers of the transmitter resonators 30D′, 30E′, 30G′, and 30H′ overlapped by the resonant receiver subsystem 14 are turned on and the power amplifiers of the transmitter resonators 30A′, 30B′, 30C′, 30F′, and 30I′ not overlapped by the resonant receiver subsystem 14 are turned off. It should be noted that receiver resonators of different sizes present significantly different impedances at point 24A to the load detector 24A of the transmitter module 20. The impedance difference measured when a given receiver resonator partially overlaps a transmitter resonator compared to when it completely overlaps the transmitter resonator is not as significant as the impedance with different receiver resonator sizes. This allows the controller 22 of any transmitter module 20A′ to 20I′ to distinguish between a small receiver resonator and a large receiver resonator that is close to the corresponding transmitter resonator 30A′ to 30I′. According to one embodiment, setting the power signal frequency and phase between transmitter resonators (e.g., 30D′, 30E′, 30G′, and 30H′) overlapped by a resonant receiver subsystem (e.g., resonant receiver subsystem 14) is described herein. In order to maximize the efficiency of transferring power from the combination of transmitter resonators 30D′, 30E′, 30G′, and 30H′ receiving power, the power signals in transmitter resonators 30D′, 30E′, 30G′, and 30H′ need to have the same frequency and be in phase with each other. The frequencies of the power signals in a given transmitter resonator 30D′, 30E′, 30G′, and 30H′ may differ within the allowed frequency band, as previously described above and with reference to FIGs. 1-10 , the requirement in this current embodiment of FIGs. 12 , 13A, and 13B is for the frequencies of the power signals in the transmitter resonators 30D′, 30E′, 30G′, and 30H′ to be adjusted to be the same and then for their phases to be locked together so that the power signals from the transmitter resonators 30D′, 30E′, 30G′, and 30H′ will be completely synchronized and in phase. In one embodiment, to ensure that the controllers 22 of overlapping transmitter resonators 30D′, 30E′, 30G′, and 30H′ all set their corresponding oscillators 26A to the same frequency, the controllers 22 of transmitter modules 20A′ through 20I′ all have the same table of frequencies selected within any given permitted frequency band (e.g., the ISM band). Within the ISM band, a number of discrete frequencies are selected for inclusion in the frequency table. Thus, the number of frequencies listed within the ISM band is finite and limited, and the frequencies in the table are spaced sufficiently widely that the various controllers 22 of transmitter modules 20D′, 20E′, 20G′, and 20H′ can determine the power signal frequency based on the first impedance difference described above. Despite the small variations in those impedances, all controllers 22 of transmitter modules 20D′, 20E′, 20G′, and 20H′ select the same discrete frequency from the permitted frequencies within the band for the power signals of their corresponding oscillators 26A and power amplifiers 26B. In one embodiment, to ensure that the transmitter resonators 30D′, 30E′, 30G′, and 30H′ all have not only the same power signal frequency but also the same phase, the following procedural steps are employed and programmed into the software of each controller 22 of the transmitter modules 20A′ through 20I′. Statistically, the first individual controller 22 of the transmitter modules 20D′, 20E′, 20G′, and 20H′ will first turn on its corresponding oscillator 26A and power amplifier 26B to supply power to the resonant receiver subsystem 14 through its transmitter resonator. The second individual controllers of the other individual controllers 22 of the transmitter modules 20D′, 20E′, 20G′, and 20H′ will measure the input impedance of their corresponding transmitter resonators and detect small secondary changes in impedance caused by the first transmitter resonator's operation using their corresponding load detectors 24A. In practice, the second controller 22 experiences a reflection from the impedance of the first transmitter resonator through its interaction with the resonant receiver subsystem 14. The second controller 22 is programmed to conclude that, based on the secondary impedance change, the other controller has first turned on its oscillator 26A and power amplifier 26B. Having made this inference, the second controller 22 then turns on its oscillator 26A and power amplifier 26B and varies the phase of its power signal while simultaneously measuring the power transmitted by its corresponding transmitter resonator using its transmitter power sensor 24B. The second controller 22 then varies the phase of its oscillator, searching for the phase at which maximum power transfer occurs and setting the oscillator phase to that value. The oscillator phase determined in this manner ensures that the phase of the power signal transmitted by the second transmitter resonator is equal to the phase of the power signal transmitted by the first transmitter resonator to the resonant receiver subsystem 14. In one embodiment, the oscillator phase is set based on substantially maximizing power transfer, rather than ensuring absolute phase balancing of the power signals. In another embodiment, again based on the transmitter resonators 30D′, 30E′, 30G′, and 30H′ being overlapped by the resonant receiver subsystem 14, the proximity of the resonant receiver subsystem 14 is detected based on the test signal power drawn by the transmitter resonators 30D′, 30E′, 30G′, and 30H′. In this embodiment, a low-amplitude power signal is initially maintained by the oscillators and power amplifiers corresponding to all transmitter resonators 30A′ to 30I′. The controllers 22 of all transmitter modules 20A′ to 20I′ then use their corresponding transmitter power sensors 24B to sense the power drawn by their corresponding transmitter resonators 30. Using their corresponding transmitter power sensors 24B, the controllers 22 of the transmitter modules 20D′, 20E′, 20G′, and 20H′ sense that power is being drawn by their corresponding transmitter resonators 30D′, 30E′, 30G′, and 30H′. Based on the detection of the drawn test signal power, the controllers 22 of the transmitter modules 20D′, 20E′, 20G′, and 20H′ turn on full power to their corresponding power amplifiers 26B. The term "first test signal power draw" is used herein to describe the power drawn from the test signal by the transmitter resonators 30D′, 30E′, 30G′, and 30H′. After a suitable test period, the test power signal can be turned off for the power amplifiers 26B of the transmitter resonators 30A′, 30B′, 30C′, 30F′, and 30I′ that are not overlapped by the resonating receiver subsystem 14. Equivalent to the impedance-based embodiment described above, the controller 22 of the transmitter modules 20D′, 20E′, 20G′, and 20H′ may require a threshold power draw in order to consider a resonant receiver subsystem 14 present proximate to its corresponding transmitter resonator 30D′, 30E′, 30G′, and 30H′. In one embodiment, to ensure that the controllers 22 of overlapping transmitter resonators 30D′, 30E′, 30G′, and 30H′ all set their corresponding oscillators 26A to the same frequency, the controllers 22 of transmitter modules 20A′ through 20I′ all have the same table of frequencies selected within any given permitted frequency band (e.g., the ISM band). Within the ISM band, a number of discrete frequencies are selected for inclusion in the frequency table. Thus, the number of frequencies listed within the ISM band is finite and limited, and the listed frequencies are spaced widely enough so that the various controllers 22 of transmitter modules 20D′, 20E′, 20G′, and 20H′ can determine the power signal frequency based on the first test signal power draw described above. Despite small variations in those power draw values, all controllers 22 of transmitter modules 20D′, 20E′, 20G′, and 20H′ select the same discrete frequency from the permitted frequencies within the band for the power signals of their corresponding oscillators 26A and power amplifiers 26B. In one embodiment, to ensure that the transmitter resonators 30D′, 30E′, 30G′, and 30H′ all have not only the same power signal frequency but also the same phase, the following procedural steps are employed and programmed into the software of each controller 22 of the transmitter modules 20A′ through 20I′. Statistically, the first individual controller 22 of the transmitter modules 20D′, 20E′, 20G′, and 20H′ will first turn on its corresponding oscillator 26A and power amplifier 26B to supply power to the resonant receiver subsystem 14 via its transmitter resonator. The second individual controllers of the other individual controllers 22 of the transmitter modules 20D′, 20E′, 20G′, and 20H′ will measure the power draw of their corresponding transmitter resonators and detect small secondary variations in the power draw due to the functioning of the first transmitter resonator via their corresponding transmitter power sensors 24B. In effect, the second controller 22 experiences a reflection from the impedance of the first transmitter resonator through its interaction with the resonant receiver subsystem 14. The second controller 22 is programmed to conclude that, based on the change in secondary power draw, the other controller has first turned on its oscillator 26A and power amplifier 26B. Having made this inference, the second controller 22 then turns on its oscillator 26A and power amplifier 26B and varies the phase of its power signal while simultaneously measuring the power transmitted by its corresponding transmitter resonator using its transmitter power sensor 24B. The second controller 22 then searches for the phase at which maximum power transfer occurs and sets the oscillator to that phase. This oscillator phase setting ensures that the phase of the power signal transmitted by the second transmitter resonator to the resonant receiver subsystem 14 is equal to the phase of the power signal transmitted by the first transmitter resonator to the resonant receiver subsystem 14. In one embodiment, the oscillator phase is set based on substantially maximizing power transfer, rather than absolutely equalizing the power signal phases. In one embodiment, when two different resonating receiver subsystems are proximate to a multi-transmitter subsystem 12′ and overlap different transmitter resonators or combinations thereof in transmitter resonators 30A′-30I′, there is no a priori reason why the two different transmitter resonators or two different groups of transmitter resonators overlapped by the two resonating receiver systems should operate at the same frequency or phase, nor is there a requirement for them to do so. The grounded shielding mesh 33′ ensures this multipath independence by decoupling all individual transmitter resonators 30A′-30I′ from one another. However, the transmitter resonators overlapped by a particular resonating receiver subsystem need to have their corresponding power signal amplifiers actively synchronized by their controllers, as described above. This can result in two different transmitter resonators or two different groups of resonators operating at two specific different locked frequencies within a frequency band, with all signals in a particular group being in phase with one another. In the foregoing, we have described how two transmitter resonators transmitting power to the same receiver resonator can be programmed to operate so that both transmitter resonators carry power signals in phase, thereby ensuring maximum power transfer. A different situation occurs when two adjacent transmitter resonators (e.g., 30A′ and 30B′ in FIG. 14 ) are transmitting to two substantially similar corresponding receiver subsystems 14A and 14B. Both transmitter resonators 30A′ and 30B′ have fringing fields with field lines extending from, for example, transmitter resonator 30A′ to receiver subsystem 14B′ and vice versa. Generally, there are no specific physical structures in system 10′ to prevent the fields of, for example, transmitter resonator 30A′ from interacting with the receiver resonators of receiver subsystem 14B. In one embodiment, when transmitter resonators 30A′ and 30B′ both serve the same large receiver resonator that overlaps them (as in FIG. 13A ), fringe fields are not inherently a problem because both transmitter resonators 30A′ and 30B′ will be operating with the same frequency power signal in phase. In the case shown in FIG. 14 , the requirement is to ensure that any fringe fields from a given transmitter resonator (e.g., 30A′) interacting with a receiver subsystem (e.g., 14B, which is designed to receive power from the adjacent transmitter resonator 30B′) do not allow power to be parasitic from transmitter resonator 30A′. One way to achieve this is to drive the two adjacent transmitter resonators 30A′ and 30B′ 180° out of phase with each other, so that the overlapping fringe fields from the transmitter resonators 30A′ and 30B′ will largely cancel each other. Since either transmitter resonator 30A′ and 30B′ treats the other transmitter resonator 30A′ and 30B′ as a parasitic when the transmitter resonator's power signals are not 180° out of phase, the controller 22 of each transmitter resonator 30A′ and 30B′ can increment the phase of the signal from each corresponding oscillator while measuring the power transmitted by the corresponding transmitter resonator 30A′, 30B′ using the corresponding transmitter power sensor 24B. The controller 22 can then search for the adjusted oscillator phase that provides the maximum transmitted power through the corresponding transmitter resonator 30A′, 30B′ and then set the oscillator's phase to the corresponding phase. The frequency and phase arrangement of each resonant receiver system, whether of similar or different sizes, as described above, ensures that both resonant receiver systems receive maximum transferred power. In a typical embodiment, there may be a large number of transmitter resonators, and several different resonant receiver subsystems may be receiving power, each receiving power from its own corresponding group of transmitter resonators at a frequency and phase selected by the controller corresponding to the transmitter resonator in the group. As a result of maximizing power transfer between each of the adjacent transmitter resonators, adjacent transmitter resonators transmitting power to different receiver subsystems may operate 180° out of phase. This process of maximizing power transfer adjusts the oscillator phases. Due to the complex impedances of various transmitter modules and slight variations in resistance, inductance, and capacitance, the phase angles of the different oscillators at the point of maximum power transfer may not be exactly equal (or exactly 180° out of phase) even when the power signals in the transmitter resonators are effectively equal (or exactly 180° out of phase). To the extent that system 10′ includes a circuit with an air gap between the primary and secondary sides, any power transfer measured or maximized in the transmitter resonator (e.g., at point 24E in FIG. 6 ) based on the measurement results of transmitter power sensor 24B can also be measured or maximized in the secondary circuit (e.g., at point 44C in FIG. 7 ) based on the measurement results of receiver power sensor 44A. This measurement result can be provided by transmitter power sensor 24B to controller 42 of receiver module 40, which in turn can transmit the measurement result to controller 22 of transmitter module 20 by one of the means described above. The concept of a multi-transmitter near-field resonant wireless power transfer system has been described above with reference to system 10′, which is configured for simultaneous capacitive power transfer and inductive power transfer according to an adjustable transfer mode ratio at a variable resonant power signal oscillation frequency. In more general embodiments, the multi-transmitter near-field resonant wireless power transfer system need not be specifically a bimodal system and can be a purely capacitive or purely inductive power transfer system. In yet another aspect, as shown in the flow chart of FIG. 15 , a wireless near-field method

[1100] for transmitting power from a multiple transmitter subsystem 12′ to a single resonant receiver subsystem 14 at a variable resonant power signal oscillation frequency includes providing

[1110] a multiple transmitter subsystem 12′ comprising a plurality of mutually independent transmitter resonators 30A′ to 30I′, each of the transmitter resonators being driven by a corresponding transmitter module 20A′ to 20I′, each transmitter module 20A′ to 20I′ being independently settable to one of a plurality of preset power signal oscillation frequencies in a preset frequency band, and all transmitter resonators 30A′ being independently settable to one of a plurality of preset power signal oscillation frequencies in a preset frequency band. to 30I′ having a common transmitting surface; positioning

[1120] a resonant receiver subsystem 14 proximate the common transmitting surface, the resonant receiver subsystem including a single receiver resonator 50 overlapping two or more of the transmitter resonators (30D′, 30E′, 30G′ and 30H in FIG. 13A ); measuring

[1130] the input impedance of each of the transmitter resonators 30A′ to 30I′; and setting

[1140] a power signal to each of the plurality of mutually independent transmitter resonators 30A′ to 30I′ to one of an off state and an active state based on the corresponding measured resonator input impedance. The method

[1100] may further include selecting a power signal oscillation frequency

[1150] for the corresponding transmitter resonator (30D', 30E', ​​30G', and 30H' in FIG. 13A) from the plurality of preset power signal oscillation frequencies based on the input impedance measured for each of the active transmitter resonators (transmitter resonators 30D', 30E', ​​30G', and 30H in FIG. 13A). The method

[1100] may further include setting

[1160] the power signal of each active transmitter resonator (30D', 30E', ​​30G', and 30H' in FIG. 13A) to a corresponding selected frequency. The method

[1100] may further include adjusting

[1170] the phase of the power signal applied to each corresponding transmitter resonator (transmitter resonators 30D′, 30E′, 30G′, and 30H in FIG. 13A ) to a phase at which power transfer through the transmitter resonator (30D′, 30E′, 30G′, and 30H′ in FIG. 13A ) is substantially maximum. In yet another aspect, as shown in the flow chart of FIG. 16 , a wireless near-field method

[1200] for transmitting power from a multiple transmitter subsystem 12′ to a single resonant receiver subsystem 14 at a variable resonant power signal oscillation frequency includes providing

[1210] a multiple transmitter subsystem 12′ comprising a plurality of mutually independent transmitter resonators 30A′ to 30I′, each of the transmitter resonators being driven by a corresponding transmitter module 20A′ to 20I′, each transmitter module 20A′ to 20I′ being independently settable to one of a plurality of preset power signal oscillation frequencies in a preset frequency band, and all transmitter resonators 30A′ to 30I′ being independently settable to one of a plurality of preset power signal oscillation frequencies in a preset frequency band. ' having a common transmitting surface; positioning

[1220] a resonant receiver subsystem 14 proximate the common transmitting surface, the resonant receiver subsystem including a single receiver resonator 50 overlapping two or more of the transmitter resonators (30D', 30E', ​​30G' and 30H' in FIG. 13A ); measuring

[1230] power drawn by each of the transmitter resonators 30A' to 30I' from a test signal; and setting

[1140] a power signal to each of the plurality of mutually independent transmitter resonators 30A' to 30I' to one of an off state and an active state based on the corresponding measured resonator test power draw. The method

[1200] may further include selecting

[1250] a power signal oscillation frequency for the corresponding transmitter resonator (30D′, 30E′, 30G′, and 30H in FIG13A ) from the plurality of preset power signal oscillation frequencies based on a measured test power drawn by each of the active transmitter resonators (transmitter resonators 30D′, 30E′, 30G′, and 30H in FIG13A ). The method

[1200] may further include setting

[1260] the power signal of each active transmitter resonator (30D', 30E', ​​30G', and 30H in Figure 13A) to a corresponding selected frequency. The method

[1200] may further include adjusting

[1270] the phase of the power signal applied to each corresponding transmitter resonator (transmitter resonators 30D′, 30E′, 30G′, and 30H in FIG13A) to a phase at which power transfer through the transmitter resonator (30D′, 30E′, 30G′, and 30H in FIG13A) is substantially maximum. In yet another embodiment, as shown in the flowchart of FIG17 , a wireless near-field method

[1300] for transmitting power from a multi-transmitter subsystem 12′ to two or more receiver subsystems 14A, 14B (in FIG14 ) at a variable resonant power signal oscillation frequency comprises: providing

[1310] a multi-transmitter subsystem 12′ comprising a plurality of mutually independent transmitter resonators 30A′ to 30I′ (in FIG14 ), each of the transmitter resonators being driven by a corresponding transmitter module 20A′ to 20I′ (see FIG13B ), each transmitter module 20A′ to 20I′ being independently settable to one of a plurality of preset power signal oscillation frequencies in a preset frequency band, and all transmitter resonators 30A′ to 30I′ having a common emitting surface; and connecting two or more resonant receiver subsystems 14A, 14B to the multi-transmitter subsystem 12′. Subsystems 14A, 14B are positioned

[1320] proximate a common transmitting surface, each resonant receiver subsystem including a single receiver resonator overlapping one or more of the transmitter resonators (transmitter resonators 30A′, 30B′ in FIG. 14 ); measuring

[1330] the input impedance of each of the transmitter resonators 30A′, 30B′; and setting

[1340] the power signal to each of the plurality of mutually independent transmitter resonators 30A′ to 30I′ to one of an off state and an active state based on the corresponding measured resonator input impedance. The method

[1300] may further include selecting a power signal oscillation frequency for the corresponding transmitter resonator 30A′, 30B′

[1350] from the plurality of preset power signal oscillation frequencies based on the input impedance measured for each of the active transmitter resonators (transmitter resonators 30A′, 30B′ in FIG. 14 ). The method

[1300] may further include setting

[1360] the power signal of each active transmitter resonator 30A', 30B' to a corresponding selected frequency. The method

[1300] may further include adjusting

[1370] the phase of the power signal applied to each corresponding transmitter resonator 30A', 30B' to a phase at which power transfer through the transmitter resonator 30A', 30B' (in FIG. 14) is substantially maximum. In yet another embodiment, as shown in the flowchart of FIG18 , a wireless near-field method

[1400] for transmitting power from a multiple transmitter subsystem 12′ to two or more receiver subsystems 14A, 14B (in FIG14 ) at a variable resonant power signal oscillation frequency includes: providing

[1410] a multiple transmitter subsystem 12′ including a plurality of mutually independent transmitter resonators 30A′ to 30I′ (in FIG14 ), each of the transmitter resonators being driven by a corresponding transmitter module 20A′ to 20I′ (see FIG13B ), each transmitter module 20A′ to 20I′ being independently set to one of a plurality of preset power signal oscillation frequencies in a preset frequency band, and all transmitter resonators 30A′ to 30I′ having a common emitting surface; arranging

[1420] the two or more resonant receiver subsystems 14A, 14B close to the common emitting surface, each resonant The receiver subsystem includes a single receiver resonator overlapping one or more of the transmitter resonators (transmitter resonators 30A′, 30B′ in FIG. 13 ); measuring

[1430] power drawn by each of the transmitter resonators 30A′ to 30I′ from a test signal; and setting

[1440] a power signal to each of the plurality of mutually independent transmitter resonators 30A′ to 30I′ to one of an off state and an active state based on the corresponding measured resonator test power draw. The method

[1400] may further include selecting a power signal oscillation frequency for the corresponding transmitter resonator 30A′, 30B′

[1450] from the plurality of preset power signal oscillation frequencies based on the input impedance measured for each of the active transmitter resonators (transmitter resonators 30A′, 30B′ in FIG. 14 ). The method

[1400] may further include setting

[1460] the power signal of each active transmitter resonator 30A', 30B' to a corresponding selected frequency. The method

[1400] may further include adjusting

[1470] the phase of the power signal applied to each corresponding transmitter resonator 30A', 30B' to a phase at which power transfer through the transmitter resonator 30A', 30B' (in FIG. 14) is substantially maximum. In yet another aspect described with reference to Figures 20A and 20B, Figures 21A and 21B, and Figures 22A and 22B, and based on the systems of Figures 1 to 10 and 12 to 14, a near-field resonant wireless power transfer system 10" for wirelessly transferring power from a photovoltaic solar cell 420 to an electrical load 70" is provided according to the schematic diagram of Figure 19A. The references in Figure 19A use an accented numbering system to clearly indicate the parallels with Figures 13A and 13B, and thereby also with Figures 6 and 7. With this numbering scheme, DC power is supplied from the solar cell 420 to the transmitter module 20" via the power conditioning unit (PCU) 430. In addition to converting the DC voltage and DC current to levels that can be further transmitted by power amplifier 26B″, PCU 430 also provides appropriately regulated voltage and current levels to drive the rest of the system components in transmitter module 20″, including the small-signal electronics. PCU 430 presents an adaptively variable load to solar cell 420 in order to adapt to the varying power provided by solar cell 420 and the varying output impedance presented by solar cell 420 to PCU 430. This allows PCU 430 to absorb power from solar cell 420 at the maximum possible rate at all times and temperatures, regardless of variations in the power from solar cell 420. Oscillator 26A″ can be used to modulate power amplifier 26B″ at a frequency suitable for wireless power transfer as described above. Power amplifier 26B″ can be of the same design as amplifier 26B shown in FIG8 , with DC power supplied from PCU 430 rather than as DC voltage source 127E. In an alternative embodiment, power amplifier 26B″ can be suitably provided with circuitry for maintaining its own oscillation, as is well known in the art of wireless systems, thereby eliminating oscillator 26A″. Power can be delivered to the transmitter resonator 30″ via a transmission tuning network 28″, which in FIG. 19A is a combination of the signal conditioning and tuning components 26C, 26D, 26E, and 26F of FIG. 6 . The transmitter resonator 30″ can have a surface area that has an extent that can be at least a substantial portion of the extent of the active solar radiation receiving surface of the solar cell 420. All of these components of the transmitter module 20″ are under the control of the controller 22″, just as the corresponding components of the transmitter module 20 in FIG. 6 are under the control of the controller 22. For clarity, not all components of the transmitter module 20″ are shown in FIG. 19A . The sensors and detectors 24A, 24B, 24C, and 24D of FIG. 6 can also be present in equivalent form in the transmitter module 20″ and connected to the controller 22″, and can perform the same functions as those described with reference to FIG. 6 . Power can be wirelessly transferred from the transmitter module 20″ to the receiver module 40″ via the transmitter resonator 30″ and the receiver resonator 50″. The power can then be transferred from the receiver module 40″ to the DC load 70″. Power can be transferred between the transmitter resonator 30″ and the receiver resonator 50″ by means of near-field wireless transmission, as described above with reference to Figures 6 to 10. The near-field wireless power transmission according to Figure 19A is not limited to bimodal and can be purely capacitive or purely inductive. Receiver module 40″ can have the same components as receiver module 40 of FIG. 7 . For clarity, a reduced set of these components is shown in FIG. 19A . Sensor 44A and detector 44B of FIG. 7 are not shown in equivalent form in FIG. 19A , but may be present. Receiver tuning network 48″ in FIG. 19A may be a combination of compensation network 46A, matching network 46B, rectifier 46D, and filter 46C. Power may be transferred from receiver tuning network 48″ to load manager 46E″, both of which may be under the control of receiver controller 42″. In the case of rectifier 46D, shown in more detail in FIG. 7 , the input impedance of this device is directly dependent on the load seen by the output of the device. In operation, the near-field resonant wireless power transfer system 10″ can function in the same manner as the near-field resonant wireless power transfer system 10 of Figures 1 and 6 to 10, with the difference being that the voltage VDD applied to each power amplifier 26B″ is replaced by a power signal from a power conditioning unit (PCU) 430, which in turn receives its power from an associated power source (in this embodiment, a solar cell 420). In another embodiment, power conditioning unit 430 can be omitted from the system shown in FIG. 19A , and instead power transfer system 10″ can be configured or operated to also function as a power conditioning system. This can be achieved, for example, by configuring controller 22″ in software, without limitation, to adjust the input DC equivalent resistance of power amplifier 26B″ based on the power level measured by transmitter power sensor 24B of FIG. 6 . The term “input DC equivalent resistance” is used herein to describe the ratio of DC voltage to DC current at the DC terminals of power amplifier 26B. While controller 22″ will make adjustments based on power measurements, it is expected that the maximum power point of the transferred power will be achieved when the input impedance of power amplifier 26B″ matches the output impedance of solar cell 420. In this embodiment, system 10″ functions as what is known in the industry as a “maximum power point tracker” and ensures that power is always transferred at a rate more suitable for the power-consuming load than would be achieved with an unregulated power supply. In another embodiment, the controller 22 ″ may be configured to measure the output impedance of the power source, which in this embodiment is the solar cell 420 , and then adjust the input impedance of the power amplifier 26B″ based on the measured output impedance of the solar cell 420 . In addition to adjusting the input impedance of power amplifier 26B″, controller 22″ can also adjust one or more of the settings of transmission tuning network 28″ and the frequency of oscillator 26A″. Furthermore, transmitter controller 22″ can make the adjustments described above based on measurements made by load detector 24A, shown in FIG6 , which provides further details regarding the circuitry of transmitter modules 20 and 20″. Load detector 24A senses the effects of load 70″ at point 24E in FIG6 . The receiver controller 42″ may also adjust one or more of the settings of the receiver tuning network 48″ and the load management system 46E″ based on measurements from the receiver power sensor 44A and the load detector 44B (both shown in FIG. 7 ) to improve the efficiency of power transfer. When considering the power conditioning functionality of system 10″, it can be appreciated that there is no a priori reason why the system's power transfer functionality should be limited to near-field wireless transmission across an air gap, as shown in FIG. 19A . Therefore, in another embodiment, a power conditioning unit 410 is shown in FIG. 19B , based on the elements of system 10″ of FIG. 19A . Transmission tuning network 28″ is in direct electrical communication with receiver tuning network 48″ via a suitable non-air gap connection 60″. This communication is via an RF power signal and constitutes the power delivered by the system. Suitable reactive electronic components can be employed in well-known configurations to decouple any DC voltage and current levels in transmitter module 20″ from those in receiver module 40″. Transmitter resonator 30″ and receiver resonator 50″ are not present in this embodiment and are eliminated by the direct communication connection between transmission tuning network 28″ and receiver tuning network 48″. The function of the power transfer system of Figures 19A and 19B as a power conditioning system can be better understood by considering Figure 19B , where simplified power conditioning concepts are absent for transmitter resonator 30″ and receiver resonator 50″, although these concepts apply equally to such resonators when present (as in Figure 19A ). The system of Figures 19A and 19B has four independent control parameters that can be adjusted during operation to regulate the power delivered to receiver module 40″ and, thereby, to load 70″. Typical commercial power conditioning units are often referred to as "boost converters" by boosting their output voltage above that of the source voltage. These devices have only two control parameters. A first independent control parameter that may be adjusted during operation to regulate the power delivered to the receiver module 40 ″ and thereby to the load 70 ″ is the oscillation frequency of the power amplifier 26B″, which may be adjusted by the controller 22 ″ in the oscillator 26A″. A second independent control parameter that can be adjusted during operation to regulate the power delivered to receiver module 40″ and, thereby, to load 70″ is the output load on rectifier 46D of receiver module 40″. This output load, in turn, directly determines the input impedance of rectifier 46D and, thereby, the input impedance of receiver module 40″. This, in turn, is the load seen by transmitter module 20″ and directly determines the input DC equivalent resistance of power amplifier 26B″. Manipulation of the output load on rectifier 46D is accomplished via load management system 46E″ of receiver module 40′ (see FIG. 19A ) under the control of receiver controller 42″. This second independent control parameter is a property of the receiver module, but inherently controls the load seen by the power supply. The control point for manipulating this parameter is load management system 46E″ of receiver module 40″. The third and fourth independent control parameters that can be adjusted during operation to regulate the power delivered to receiver module 40″ and, thereby, to load 70″ are properties of rectifier 46D (see FIG. 7 ) and power amplifier 26B″ ( FIG. 19A ) of receiver module 40″, and are essentially similar but completely independent of each other. Both rectifier 46D and power amplifier 26B″ comprise multi-terminal amplifying devices that rely on a voltage signal applied to a third terminal of each device to modulate the passage of current between two terminals of the multi-terminal device. The simplest multi-terminal amplifying device that can be used in each of rectifier 46D and power amplifier 26B″ is a transistor. This allows a phase difference to exist between the voltage signal and the current signal generated by or in the device. This voltage-current phase difference can be adjusted via the applied voltage. Rectifier 46D can be a phase-adjustable RF rectifier whose voltage-current phase difference can be adjusted via receiver controller 42″. In the case of power amplifier 26B″, this voltage-current phase difference may be adjusted via transmitter controller 22″. Rectifier 46D may effectively comprise a differential self-synchronous radio frequency rectifier. Rectifier 46D may comprise a differential switched-mode self-synchronous radio frequency rectifier. The examples of Figures 19A and 19B are based on transmitting power from a solar cell, or further, from a solar cell array, wherein the power delivered by solar cell 420 can vary significantly, down to zero, depending on sunlight. Numerous other power sources exist that suffer from variable output, both in terms of power and the voltage generated. These include power turbines, wind turbines, and various batteries and storage batteries. Wind turbines can vary significantly in their power generation, and various batteries can have a wide range of power consumption curves. Given the system's power transmission efficiency, either system 10" or 410 can be configured to receive power, for example, without restriction, from commercial batteries with a slow open-circuit voltage decay curve. Load management system 46E" can be configured to vary the input DC equivalent resistance of power amplifier 26B" as described above, and controllers 22" or 42" can be configured to provide a desired voltage level to load 70" until this voltage can no longer be maintained by the transmitted power and the adjustability of the parameters of systems 10" or 410. FIG19A and its associated description illustrate near-field wireless power transfer from a single solar cell 420 to a single load 70″ (typically a battery). In practical implementations of larger solar cell power systems, typically employing battery arrays, a power transfer scheme similar to that described with reference to FIG12 , FIG13A , and FIG13B can be employed, with multiple transmitter subsystems and typically a single receiver subsystem. This is illustrated in FIG20A and FIG20B , which are exploded front and rear views, respectively, of a solar panel 400 having a transparent solar cover 440 and one near-field wireless transmission subsystem per solar cell 420, thereby, by way of example, including sixty near-field wireless power transmission subsystems 16, each including a transmitter resonator 30″, a transmitter module 20″, and a power conditioning unit 430, as described with reference to FIG19A . To avoid clutter, transmit subsystem 16 is not labeled in FIG. 19A , but is indicated and labeled in FIG. 20B , FIG. 21B , and FIG. 22B , as further described below. In one embodiment, coupling each individual solar cell of a solar panel composed of a plurality of solar cells to a power transmission and management system allows for cell-level power management. By providing power management at each individual cell, power collection can be optimized for each cell, resulting in improved efficiency for the entire solar panel system. In this embodiment, the impact of individual cell failures or poor connections between cells is mitigated. Individual cell-level power collection allows for maximum power harvesting even in less-than-ideal conditions, such as rain, shadows, or when debris covers a portion of the solar panel. To avoid clutter, only one near-field wireless power transmission subsystem 16 is labeled in FIG20B . In both FIG20A and FIG20B , the transmitter resonator 30″ of each transmission subsystem 16 can be located on the backside of its corresponding solar cell 420. As seen from the front side of the panel in FIG20A , the flat area of ​​the solar cell represents the active solar radiation receiving and energy conversion semiconductor device itself and is correspondingly labeled 420, while as seen from the back side in FIG20B , the flat area of ​​the device represents the transmitter resonator and is correspondingly labeled 30″. The transmitter resonator 30″ can have a surface area that extends for at least a substantial portion of the extent of the active solar radiation receiving surface of the solar cell 420. The transmitter module 20″ and power conditioning unit 430 of each near-field wireless power transmission subsystem 16 are combined in FIG20B and labeled 450. To avoid clutter, the combined assembly 450 is not labeled in FIG19A, but is indicated as a unit and labeled in FIG20B, FIG21B, and FIG22B, as further described below. A single receiver resonator 50" can be assembled in the frame 460 of the solar panel 400. A single receiver module 40" can be mounted directly on the back of the receiver resonator 50". In operation, the near-field resonant wireless power transfer system 10″ can function in the same manner as the near-field resonant wireless power transfer system 10 of Figures 12, 13A, and 13B, except that the voltage VDD applied to each of the power amplifiers 26B″ is replaced by a power signal from a power conditioning unit (PCU) 430, which in turn receives its power from the associated solar cell 420. 20A and 20B , the frame 460 can be configured as a receiver resonator adapted to receive power from all transmitter resonators 30″, and the receiver module 40″ can be located on the frame 460. In this embodiment, the plate within the frame 460 is not a resonator but can be a simple flat sheet of non-conductive material. In another embodiment, solar panels 400', shown in front and rear views of Figures 21A and 21B, respectively, enable each near-field wireless power transmitter subsystem to transfer power to one near-field wireless power receiver subsystem. Although frame 460 is shown as being filled with an opaque plate 470, plate 470 may not be part of the near-field circuitry or magnetic circuit. For clarity, the same component numbering as in Figures 20A and 20B is used on the transmitter side. On the receiver side, the numbering of Figure 19A is used. Again, to avoid clutter, only one receiver-side device is labeled. In operation, the solar panel arrangement 400' of Figures 21A and 21B can have individual transmitter modules 20" linked by hard wires (not shown) so that the transmitter modules can be in phase, thereby minimizing power loss during transmission. In other embodiments, the transmitter modules 20" can be independent and function as described in Figures 14, 17, and 18. In yet another embodiment, shown as a solar panel arrangement 400″ in the front view of FIG. 22A and the rear view of FIG. 22B , respectively, an array of twenty-five solar cells 420 is shown, arranged, for example, in five rows. Each solar cell 420 has a transmitter resonator 30′ at its rear end, including its corresponding transmitter module 20″, and a unit 450′ including a power conditioning unit 430. At the bottom and top of the array, and between each two rows of solar cells, are receiver resonators 50″ arranged in a plane substantially perpendicular to the plane of the solar cells 420. Each receiver resonator 50″ is in wired electrical communication with its corresponding receiver module 40″. As with the previous solar panel embodiments, one example of each component is labeled. As with the embodiments shown in FIG. 20A and FIG. 20B and FIG. 21A and FIG. 21B , in some embodiments, the solar panel arrangement 400″ may also have a frame 460. For clarity, the frame 460 is not shown in Figures 22A and 22B. In operation, the transmitter resonators 30″ of the solar cells 420 in a row of the system 400″ transmit power to the receiver resonators 50″ both above and below the transmitter resonators. In this embodiment, however, there is an additional mechanism by which various nearest neighbor receiver resonators 50″ are resonantly coupled and the collected power is shared between the receiver resonators. The collected power aggregated by all receiver resonators 50″ of the array can thus be tapped off via any one or more of the various receiver modules 40″. In certain embodiments, the power collected by all receiver modules 40″ can be tapped off only via the bottommost receiver module 40″, by way of example. Any of the receiver modules 40″ on any receiver resonator 50″ can function as a receiver module to collect power for a row of solar cells 420, while also functioning as a transmitter module to transmit the collected power to another receiver resonator 50″ in its vicinity via its associated receiver resonator 50″. This action may be repeated down the array to deliver power to the bottom-most receiver module 40 ″. In another embodiment of the system of Figures 22A and 22B, a frame (similar to the frame 460 of Figures 20A and 20B) surrounding the planar perimeter of the solar cell array of Figures 22A and 22B can be a receiver resonator that carries receiver modules 40' and can receive power from various receiver resonators 50". In this way, the total power generated by all solar cells 420 in the array can be received by the resonator frame 460 and tapped via the receiver modules 40" for further electrical transmission. Power collection at the individual solar cell level can be accomplished with a wired connection. However, using a wireless transmission system in solar panels allows for a reduction in wiring and, therefore, manufacturing costs. In another embodiment described in the flowchart of reference Figure 23, a method

[1500] for transmitting power from a photovoltaic cell 420 to an electrical load 70'' is provided, the method comprising: converting

[1510] power from the photovoltaic cell 420 into an oscillating power signal having an oscillating frequency in a transmitting module 20''; transmitting

[1520] the power to a transmitter resonator 30'' that is in wired electrical communication with the transmitting module 20'' and is configured to resonate at the oscillating frequency; receiving

[1530] the power in a receiver resonator 50'' that is configured to resonate at the oscillating frequency and is arranged to receive power from the transmitter resonator 30'' via at least one of capacitive coupling and magnetic induction; receiving

[1540] the power in a receiver module 40'' that is in wired electrical communication with the receiver resonator 50''; and providing

[1550] the received power to the electrical load 70'' in the form of direct current via wired electrical communication. The method may further include converting the voltage and current of the power from the photovoltaic cell 420 to a voltage and current suitable for the transmitting module 20 ″ before converting the power into the oscillating power signal. In yet another embodiment of the method described with reference to FIG. 19A and the flow chart in FIG. 24 , a method

[1600] for transmitting power from an array 400 of photovoltaic cells 420 to an electrical load 70′′ is provided, the method comprising: converting

[1610] power from each of the photovoltaic cells 420 in the array 400 into an oscillating power signal having an oscillating frequency in each of a first plurality of corresponding transmitting modules 20′′; transmitting

[1620] power in each of the transmitting modules 20′′ to a corresponding transmitting resonator 30′′ in a second plurality of transmitting modules 20′′; 1630] power in a receiver resonator 50'' configured to resonate at the oscillation frequency and arranged to receive power from the plurality of transmitter resonators 30'' via at least one of capacitive coupling and magnetic induction; receiving

[1640] power in a receiver module 40'' in wired electrical communication with the receiver resonator 50''; and providing

[1650] the received power to an electrical load 70'' in the form of direct current via the wired electrical communication. The method may further include converting the voltage and current of the power from each photovoltaic cell 420 to a voltage and current suitable for the corresponding transmitter module 20'' before converting the power into the oscillating power signal. Receiving

[1630] power in the receiver resonator 50'' may include receiving power in receiver resonators arranged around a planar perimeter of the array 400 of photovoltaic cells. In yet another embodiment of the method described with reference to FIG. 19A and the flow chart in FIG. 25 , a method

[1700] for transmitting power from an array 400′ of photovoltaic cells 420 to an electrical load 70″ is provided, the method comprising: converting

[1710] power from each of the photovoltaic cells 420 in the array 400′ into an oscillating power signal having an oscillating frequency in each of a first plurality of corresponding transmitting modules 20″; transmitting

[1720] power from each of the transmitting modules 20″ to a corresponding transmitter resonator 30″ in a second plurality of transmitter resonators 30″, wherein each transmitter resonator 30″ '' configured to resonate at an oscillation frequency; receiving

[1730] power from each transmitter resonator 30'' in a corresponding receiver resonator 50'' configured to resonate at the oscillation frequency, wherein each receiver resonator 50'' is further configured and arranged to receive power from the transmitter resonator 30'' via at least one of capacitive coupling and magnetic induction; receiving

[1740] power from each receiver resonator 50'' in a corresponding receiver module 40'' in wired electrical communication with the receiver resonator 50''; and providing

[1750] the received power to the electrical load 70'' in the form of direct current via wired electrical communication. The method may further include converting the voltage and current of the power from each photovoltaic cell 420 to a voltage and current suitable for the corresponding transmitter module 20'' before converting the power into the oscillating power signal. In yet another embodiment described with reference to FIG. 19A and the flow chart in FIG. 26 , a method

[1800] for transmitting power from an array 400′′ of photovoltaic cells 420 to an electrical load 70′′ (in FIG. 19A ) is provided, the method comprising: converting

[1810] power from each of the photovoltaic cells 420 in the array 400′′ into an oscillating power signal having an oscillation frequency in each of a first plurality of corresponding transmitting modules 20′′; transmitting

[1820] power from each of the transmitting modules 20′′ to a transmitter resonator 30′′ in a second plurality of transmitter resonators 30′′, wherein each transmitter resonator 30′′ is configured to resonate at the oscillation frequency; and transmitting

[1820] power from each of the transmitting modules 20′′ to a transmitter resonator 30′′ in a third plurality of receiver resonators 30′′. receiving

[1830] power from each transmitter resonator 30'' in any adjacent receiver resonator 50'' in the resonator 50'', the receiver resonators being configured to resonate at an oscillation frequency, wherein each receiver resonator 50'' is further configured and arranged to receive power from the transmitter resonator 30'' via at least one of capacitive coupling and magnetic induction; sharing

[1840] the received power among the third plurality of receiver resonators 50''; and providing

[1850] the received power in the form of direct current to the electrical load 70'' via wired electrical communication, the received power being received from one or more of the third plurality of receiver resonators 50'' via corresponding one or more receiver modules 40''. The method may further include converting the voltage and current of the power from each photovoltaic cell 420 to a voltage and current suitable for the corresponding transmitter module 20'' before converting the power into the oscillating power signal. FIG27A shows a representative portion 500 of an expanded near-field wireless power distribution system in an electric vehicle having a conductive chassis 510. In this embodiment of the general system 10″ of FIG19A, the power source is a rechargeable battery 520 rather than a solar cell 420, and the load 70″ is an electric motor 530 rather than a battery as in FIG19A. The system shown in FIG14A may optionally include a power conditioning unit 430 as in FIG19A. In other embodiments, the transmitter modules may function in conjunction to provide power conditioning as described above with reference to FIG19B. The system shown in FIG27A and described in more detail below can operate via capacitive power transfer, inductive power transfer, or bimodal power transfer. Referring to FIG4B and FIG19A, transmitter resonator 30″ includes a dielectric element 138 sandwiched between conductive antennas 132 and 134. Referring to FIG4B and FIG19A, receiver resonator 50″ includes a dielectric element 158 ​​sandwiched between conductive antennas 152 and 154. Transmitter module 20″ is shown mounted directly to antenna 132, which also serves as a frame or support for battery 520. Transmitter module 20″ can be electrically connected between battery 520 and transmitter resonator 30″. Receiver module 40″ is shown mounted directly to electric motor 530. Receiver module 40″ can be electrically connected between receiver resonator 50″ and electric motor 530. FIG27B shows a representative portion 500 of an expanded near-field wireless power distribution system in an electric vehicle having a conductive chassis 510. In an embodiment of the general system 10″ of FIG19A, again as in FIG27A, the power source is a rechargeable battery 520 rather than a solar cell 420, and the load 70″ is an electric motor 530 rather than a battery as in FIG19A. The system shown in FIG27B may optionally include a power conditioning unit 430 as in FIG19A. In other embodiments, the transmitter module 20″ and the receiver module 40″ may function in conjunction to provide power conditioning as described above with reference to FIG19B. The system shown in FIG27B and described in more detail below can operate via capacitive power transfer, inductive power transfer, or bimodal power transfer. Referring to FIG4B and FIG19A, transmitter resonator 30″ includes dielectric element 138 sandwiched between conductive antennas 132 and 134. Referring to FIG4B and FIG19A, receiver resonator 50″ includes dielectric element 158 ​​and conductive antennas 152 and 154 of FIG27A; in this embodiment, receiver resonator 50″ is absent. Transmitter module 20″ is shown mounted directly to antenna 132, which also serves as a frame or support for battery 520. Transmitter module 20″ can be electrically connected between battery 520 and transmitter resonator 30″. Receiver module 40″ is shown mounted directly to electric motor 530. In this embodiment, receiver module 40″ can be electrically connected between electric motor 530 and chassis 510. In this arrangement, there is sufficient coupling between chassis 510 and antenna 152 for suitably efficient power transfer.The electrically conductive mechanical components of the system (i.e., components having, for example, a load-bearing structural function in the system) may thereby form part of the resonant structure of the power transfer system. In the embodiment shown in Figures 27A and 27B, the focus is specifically on power supplied to an electric motor 530 to drive one of the vehicle's wheels, but an equivalent arrangement may be implemented for any electrical subsystem on the vehicle using a plurality of suitably adapted receiver modules 40'', with the transmitter module 20'' providing power to all receiver modules. The arrangement of FIG27A and FIG27B for transmitting power from a battery to the electrical subsystem of a vehicle largely avoids the extremely complex automotive wiring harness that creates difficulties during vehicle manufacturing and is a source of considerable manufacturing costs. The embodiment in FIG27A and FIG27B , along with its extension to other electrical subsystems of a vehicle, can be described as an "extended near-field wireless power distribution system." In addition to the other wheels of the electric vehicle, the arrangement can be extended to headlights and other vehicle accessories, including, without limitation, interior lights, dashboard displays, measuring instruments, digital electronic devices, navigation systems, warning systems, etc. This application is not limited to electric vehicles. It can be applied to hybrid or internal combustion vehicles to distribute electricity as needed and when needed. It can be similarly applied to other vehicles that use any electrical system that requires electricity. Examples include, without limitation, motorized or non-motorized bicycles, aircraft, boats, and other vehicles that use onboard power supplies. Batteries or power supplies do not have to be limited to vehicles. The principles described with respect to Figures 1 to 11, Figures 19A and 19B, and Figures 27A and 27B are also applicable to fixed and onboard systems that need to be supplied with electricity from a geostationary source (e.g., a fixed track that is used to supply electricity to a mobile vehicle without limitation). FIG28A shows another embodiment of the general system 10″ of FIG19A in a power supply system 600 for supplying power to a computer monitor 610 located on a tabletop 620 with power from a suitable source via the primary side 12 according to FIG1 and, in more detail, FIG6 . In this system 600, both the transmitter module 20″ and the transmitter resonator 30″ of FIG19A are incorporated into the primary side 12. In this arrangement of system 600, the receiver resonator 50″ according to FIG19A forms the base of the monitor 610. The receiver module 40″ of FIG19A can be incorporated into the base of the monitor 610. Alternatively, the receiver module 40″ of FIG19A can be incorporated into the monitor 610 itself. Referring to FIG4B , the antenna 152 forms the bottom of the base of the monitor 610 and is separated from the antenna 154 by a dielectric element 158. The housing and structural frame 630 of the monitor 610 can be at least partially conductive and serve as one continuous conductor to electrically supply the power signal from the antenna 154 via the receiver module 40″ (see FIG. 19A ) to the circuitry of the monitor 610, which represents the loaded resonator 70″ of FIG. 19A . Other electrical connectors from the antenna 152 to the circuitry of the monitor 610 extend upward from the antenna 152 along the base of the monitor 610. In other embodiments, the housing and structural frame 630 of the monitor 610 can be a non-conductive polymer and a separate conductor can extend from the antenna 154 to the circuitry of the monitor 610, which represents the loaded resonator 70″ of FIG. 19A . As shown in another embodiment of a power supply system 600' for supplying power to a computer monitor 610 in FIG. 28B , the base of the monitor 610 may include only the antenna 152 and the dielectric element 158. In this embodiment, a metallic conductive portion of the monitor housing or frame 630 acts as the antenna, rather than the antenna 154, and the housing or frame 630 is sufficiently coupled to the antenna 152 beneath the dielectric element 158 ​​to provide sufficiently efficient power transfer. The receiver module 40" of FIG. 19A may be incorporated into the base of the monitor 610. Alternatively, the receiver module 40" of FIG. 19A may be incorporated into the monitor 610 itself. The housing and structural frame 630 of the monitor 610 may serve as a continuous electrical conductor to supply a power signal via the receiver module 40" to the circuitry of the monitor 610, representing the load resonator 70" of FIG. 19A. The system 600 may optionally include a power conditioning unit 430 as shown in FIG. 19A . In some embodiments, the transmitter module 20″ and the receiver module 40″ can function in conjunction to provide power conditioning as described with reference to FIG. 19A using near-field wireless power transfer. The near-field wireless power transfer system of FIG. 28A eliminates the need for cumbersome cables to supply power to the monitor 610 and utilizes the system's mechanical structural elements as integral electrical / electronic components in the power transfer arrangement. As described with reference to the flowchart in FIG. 29 and the systems of FIG. 19A and FIG. 19B , a method

[2000] for transmitting power from a DC power source 420 to an electrical load 70′′ is provided, the method comprising: providing

[2010] an electrical power transmission system 10′′, 410 in wired electrical communication with the power source 420, the electrical power transmission system 10′′, 410 comprising: an oscillator 26A′′ capable of oscillating at an oscillation frequency, a power amplifier 26B′′ and a transmitter tuning network 28′′ both under the control of a transmitter controller 22′′, and a receiver tuning network 48′′ and a load management system 46E′′ both under the control of a receiver controller 42′′, wherein the load management system 46E′′ is in wired electrical communication with the electrical load 70′′ ; converting

[2020] the power from the power supply 420 into an oscillating power signal having an oscillating frequency in the power amplifier 26B′′; transmitting

[2030] the power signal from the power amplifier 26B′′ to the load management system 46E′′ via the transmitter tuning network 28′′ and the receiver tuning network 48′′ under the control of the transmitter controller 22′′; adjusting

[2040] at least one of the oscillation frequency, the input DC equivalent resistance of the power amplifier 26B′′, the transmitter tuning network 28′′, the receiver tuning network 48′′ and the load management system 46E′′ to change the rate of power transmission; and providing

[2050] the power received by the load management system 46E′′ in the form of direct current to the power load 70′′ via wired electrical communication. Transmitting

[2030] the power signal via the transmitter tuning network 28″ and the receiver tuning network 48″ may include transmitting power via wired communication or via wireless communication. Transmitting power via wireless communication may include transmitting power via near-field wireless communication. Transmitting power via near-field wireless communication may include transmitting power via at least one of capacitive coupling and inductive coupling. Transmitting power from the DC power source 420 may include transmitting power from at least one solar cell 420. Transmitting power from the DC power source may include transmitting power from at least one battery. Transmitting power from the DC power source may include transmitting power from a power source having a varying voltage. In another embodiment described with reference to the flowchart in Figure 30 and considering more deeply the system of Figures 19A and 19B, a method

[2100] is provided for transmitting power from a DC power source 420 to an electrical load 70'', the method comprising: providing

[2110] a power transmission system 10'', 410 in wired electrical communication with the power source 420, the power transmission system 10'', 410 including an RF power amplifier 26B'' in RF communication with an adjustable phase RF rectifier 46D (see Figure 7), the adjustable phase RF rectifier being in wired electrical contact with the electrical load 70''; converting

[2120] the power from the DC power source 420 into an RF oscillating power signal in the power amplifier 26B''; converting

[2130] the RF oscillating power signal into a DC power signal in the rectifier 46D; and adjusting

[2140] the efficiency of the power transmission by adjusting the current-voltage phase characteristic of the rectifier 46D. Providing an adjustable phase RF rectifier may include providing a differential self-synchronous RF rectifier 46D. The method

[2100] may further include adjusting the efficiency of the power transfer by adjusting the DC equivalent input resistance of the power amplifier 26B''. Providing

[2110] the power transfer system 10'', 410 may include providing a load management system 46E'' in wired communication between the rectifier 46D and the load 70''. Adjusting the DC equivalent input resistance of the power amplifier 26B'' may include adjusting the input impedance of the rectifier 46D by adjusting the load management system 46E''. Adjusting the load management system 46E'' may include automatically adjusting the load management system 46E''. The method

[2100] may further include adjusting the efficiency of the power transfer by adjusting the current-voltage phase characteristic of the power amplifier 26B". Providing

[2110] the power transfer system 10", 410 may include providing a transmitter controller 22" in communication with the power amplifier 26B" to control the power amplifier 26B". Adjusting the current-voltage phase characteristic of the power amplifier 26B" may be performed by the transmitter controller 22". Adjusting the current-voltage phase characteristic of the power amplifier 26B" may be performed automatically by the transmitter controller 22". The method

[2100] may further include adjusting the efficiency of the power transfer by changing the oscillation frequency of the power amplifier 26B''. Providing

[2110] the power transmission system 10", 410 may include providing a receiver controller 42" in communication with the rectifier 46D to control the rectifier 46D. Adjusting the current-voltage phase characteristic of the rectifier 46D may be performed by the receiver controller 42". Adjusting the current-voltage phase characteristic of the rectifier 46D may be performed automatically by the receiver controller 42". Providing

[2110] the power transfer system 10", 410 may include providing a power amplifier 26B" for direct wired RF communication with the adjustable phase RF rectifier 46D (via connection 60" of FIG. 19B ). Providing

[2110] the power transfer system 10", 410 may include providing a power amplifier 26B" for wireless near-field RF communication with the adjustable phase RF rectifier 46D. Providing

[2110] a power transfer system 10'', 410 may include providing a transmitter resonator 30'' in wired radio frequency communication with a power amplifier 26B' ​​and a receiver resonator 50'' in wired radio frequency communication with an radio frequency rectifier 46D. The method

[2100] may further include operating the transmitter resonator 30'' and the receiver resonator 50'' in wireless near-field radio frequency communication with each other. Providing

[2110] a power transfer system 10'', 410 may include providing a power amplifier 26B'' in at least one of capacitive near-field wireless radio frequency communication and inductive near-field wireless radio frequency communication with the rectifier 46D. Providing

[2110] a power transfer system 10'', 410 may include providing a power amplifier 26B'' in bimodal wireless near-field communication with the rectifier 46D. The method

[2100] may further include: providing a power conditioning unit 430 electrically disposed between the power source 420 and the power transmission system 10''; and adjusting the power conditioning unit 430 to adjust at least one of the current and voltage from the power source 420 to improve the efficiency of the power transmission. Based on a more in-depth consideration of the systems of Figures 19A and 19B and with reference to Figure 7, a general power transmission system 10", 410 for supplying power from a DC power source 420 to an electrical load 70" includes: an RF power amplifier 26B" in wired electrical communication with the power source 420 and configured to convert a DC voltage from the power source 420 into an AC voltage signal having an oscillating frequency; an adjustable phase RF rectifier in wired electrical contact with the electrical load 70" and in RF communication with the power amplifier, the rectifier configured to receive power transmitted from the power amplifier 26B"; and a receiver controller 42" in communication with the rectifier 46D, the receiver controller configured to adjust the efficiency of power transmission from the power amplifier 26B" to the rectifier 46D by adjusting the current-voltage phase characteristic of the rectifier 46D. The receiver controller 42" can be configured to automatically adjust the current-voltage phase characteristic of the rectifier 46D. The rectifier may be a differential self-synchronous radio frequency rectifier. The power transmission system 10″, 410 may further include a load management system 46E″ that is in wired communication with the load 70″ and is provided between the load 70″ and the rectifier 46D in a power signaling manner. The load management system 46E″ is configured to increase the efficiency of power transmission by adjusting the input impedance of the rectifier 46D. The load management system 46E″ may be configured to automatically adjust the input impedance of the rectifier 46D. The power transmission system 10″, 410 may further include a transmitter controller 22″ in communication with the power amplifier 26B″, the transmitter controller 22″ being configured to increase the efficiency of the power transmission by adjusting the current-voltage phase characteristic of the power amplifier 26B″. The transmitter controller 22″ may be configured to automatically adjust the current-voltage phase characteristic of the power amplifier 26B″ to increase the efficiency of the power transmission. The power transfer system 10 ″, 410 may further include an oscillator 26A″ in communication with the power amplifier 26B″ and the transmitter controller 22 ″. The transmitter controller 22 ″ may be configured to adjust the oscillation frequency via the oscillator 26A″. The power amplifier 26B″ can be in direct wired RF communication with the adjustable phase RF rectifier 46D (via connection 60″ of FIG. 19B ). The power amplifier 26B″ can be in wireless near-field RF communication with the adjustable phase RF rectifier 46D. The power transfer system 10″, 410 can include a transmitter resonator 30″ in wired RF communication with the power amplifier 26B″ and a receiver resonator 50″ in wired RF communication with the rectifier 46D. The transmitter resonator 30″ and the receiver resonator 50″ can be in wireless near-field RF communication with each other. The power amplifier 26B″ can be in at least one of capacitive near-field wireless RF communication and inductive near-field wireless RF communication with the rectifier 46D. The power amplifier 26B″ can be in dual-peak near-field wireless RF communication with the rectifier 46D. The power transfer system may further include a power conditioning unit 430 electrically disposed between the power source 420 and the power amplifier 26B″, the power conditioning unit 430 being configured to adjust at least one of the current and voltage from the power source 420 to improve the efficiency of power transfer. In another embodiment described with reference to Figures 19A, 19B, 27A and 27B, and 28A and 28B, an electric system includes: a mechanical load-bearing structure 510, 630 having a conductive first portion; an electrical load; and a power transfer system 10'', 410 including at least one radio frequency resonator 30'', 50'' configured for near-field wireless power transfer, wherein the resonator at least partially includes the conductive first portion. The electric system may further include a rechargeable battery 520, and the electrical load may include an electric motor 530. The electric system may be an electric vehicle 500, 500', and the mechanical load-bearing structure may include a chassis 510 of the vehicle. The electric system may be a display monitor 610, and the mechanical load-bearing structure may be at least one of a frame 630 and a base of the monitor. The power system may further include a power supply. The power transmission system may include: an RF power amplifier 26B″ in wired electrical communication with the power supply and configured to convert a DC voltage from the power supply into an AC voltage signal having an oscillating frequency; an adjustable phase RF rectifier 46D in wired electrical contact with the power load 70″ and in RF communication with the power amplifier 26B″; the rectifier 46D configured to receive power transmitted from the power amplifier 26B″; and a receiver controller 42″ in communication with the rectifier 46D, the receiver controller 42″ being configured to adjust the efficiency of power transmission from the power amplifier 26B″ to the rectifier 46D by adjusting the current-voltage phase characteristic of the rectifier 46D. In another embodiment, as described in Figures 19A and 19B, Figures 27A and 27B, and Figures 28A and 28B, an apparatus includes: a mechanical load bearing structure 510, 630 having a conductive first portion; a power source; an electrical load 70'', 530, 610; and a power delivery system 10'', 410, including: an RF power amplifier 26B'' in wired electrical communication with the power source and configured to convert a DC voltage from the power source into an AC voltage signal having an oscillating frequency; an adjustable phase RF rectifier 46D in communication with the electrical load 70' ' makes wired electrical contact and is in radio frequency communication with the power amplifier 26B''; a rectifier 46D, configured to receive power transmitted from the power amplifier 26B''; and a receiver controller 42'', which communicates with the rectifier 46D, and the receiver controller 42'' is configured to adjust the efficiency of power transmission from the power amplifier 26B'' to the rectifier 46D by adjusting the current-voltage phase characteristic of the rectifier 46D; wherein the conductive first portion is configured to carry at least one of the radio frequency signal from the power amplifier 26B'' and the radio frequency signal to the rectifier 46D. The device may further include a load management system 46E″ in wired communication with the load 70″ and disposed between the load 70″ and the rectifier 46D in a power signal manner, the load management system 46E″ being configured to increase the efficiency of power transmission by adjusting the input impedance of the rectifier 46D. The device may further include a transmitter controller 22″ in communication with the power amplifier 26B″, the transmitter controller 22″ being configured to increase the efficiency of power transmission by adjusting the current-voltage phase characteristic of the power amplifier 26B″. The device may further include an oscillator 26A″ in communication with the power amplifier 26B″ and the transmitter controller 22″, wherein the transmitter controller 22″ is configured to adjust the oscillation frequency via the oscillator 26A″. The power amplifier 26B″ can be in direct wired RF communication with the rectifier 46D via the conductive first portion. The power amplifier 26B″ can be in wireless near-field RF communication with the rectifier 46D. The power transmission system 10″, 410 can include a transmitter resonator 30″ in wired RF communication with the power amplifier 26B″ and a receiver resonator 50″ in wired RF communication with the rectifier 46D, and one of the transmitter resonator 30″ and the receiver resonator 50″ can include the conductive first portion. The transmitter resonator 30″ and the receiver resonator 50″ can be in wireless near-field RF communication with each other. The power amplifier 26B″ can be in at least one of capacitive near-field wireless RF communication and inductive near-field wireless RF communication with the rectifier 46D. The power amplifier 26B″ can be in bimodal near-field wireless RF communication with the rectifier 46D. The DC power supply can include a rechargeable battery 520, and the load can include an electric motor 530. In another embodiment schematically shown in FIG32 and based on FIG6, FIG7, FIG8 and FIG9, a sealed bidirectional power transmission circuit device 800 is provided, which has a plurality of terminals configured to electrically communicate with a device outside the sealed device 800. The sealed device 800 includes, in its sealed interior, a multi-terminal power switching (MPS) device 810 having at least one DC terminal, at least one AC terminal and at least one control terminal. The MPS device 810 is adjustable between an amplification state and a rectification state, and is configured to bidirectionally transmit a DC voltage and a DC current via the at least one DC terminal, and transmit the DC voltage and the DC current via the at least one AC terminal. The PFDCA circuit 820 is configured to bidirectionally transmit an RF power signal having an amplitude, frequency, and phase through the AC terminals; and a phase, frequency, and duty cycle adjustment (PFDCA) circuit 820 in wired data communication with the controller 880. The PFDCA circuit is in wired electrical communication with the MPS device 810 via at least one control terminal. The PFDCA circuit 820 is configured to establish an RF oscillating signal having the frequency and phase of the RF power signal at at least one control terminal of the MPS device 810, and to adjust the MPS device 810 between an amplifying mode and a rectifying mode by adjusting the phase of the RF oscillating signal under the control of the controller 880. The PFDCA circuit 820 may be further configured to establish a duty cycle for the RF oscillating signal. The PFDCA circuit 820 may include an RF oscillator for generating the RF oscillating signal under the control of the controller 880. The term "multi-terminal power switching device" is used herein to describe a device having at least three terminals and capable of switching or modulating current flowing between at least two of the terminals based on a signal applied to at least one third terminal of the device. Suitable MPS devices 810 include, but are not limited to, mechanical relay switches, solid-state switches, electro-optical switches (also known as optical switches), thyristors, waveguide switches, transistors (including, for example, MOSFETs, MESFETs, III-V semiconductor transistor devices, and BJT devices), and power transistor devices (including, for example, triodes and pentodes). In some embodiments, a circuit is sealed with a polymeric coating or mold to form a seal or sealed device. In some embodiments, a sealed device protects components located on the interior of the device. In some embodiments, the seal of the device provides electrical insulation to prevent static discharge, short circuits, or other harmful discharges that could damage components of the device. In some embodiments, a sealed device protects internal components from oxidation. In some embodiments, the seal can form a waterproof barrier or a water vapor barrier. In some embodiments, the seal facilitates electrical connection to the device by providing access to one or more terminals on the exterior of the sealed device. The sealed power transmission circuit device 800 may further include a tuning network 830 within the sealed enclosure in wired data communication with a controller 880. The tuning network is in wired electrical communication with the MPS device 810 via at least one AC terminal. The tuning network 830 is configured to adjust the RF power signal to a tuned RF power signal from the tuning network 830 under instructions from the controller 880 when the MPS device 810 is in an amplifying state. The tuning network 830 may include a harmonic termination network circuit of the type shown in Figures 8 and 9, configured to suppress harmonics of the RF oscillation signal in the RF power signal. As shown in Figures 8 and 9, the harmonic termination network may include one or more inductors and one or more of the first harmonic terminations 127I, 147G, the second harmonic terminations 127H, 147F, and the third harmonic terminations 127F, 147D. The sealed power transmission circuit device 800 may include an amplitude / frequency / phase detector (AFPD) 840 within the sealed enclosure, in wired data communication with a controller 880. The AFPD 840 is configured for wired electrical communication with the tuning network and is configured to determine the amplitude, frequency, and phase of any RF power signal transmitted between the tuning network and an AC load / source external to the sealed device. To this end, according to FIG. 32 , the AFPD 840 measures the amplitude, frequency, and phase of the signal at the output of the tuning network 830 derived from the device 800. The PFDCA circuit 820 is configured to receive instructions from the controller 880 based on the measurement data transmitted by the AFPD 840 to the controller 880. In other embodiments not shown in FIG. 32 , the PFDCA circuit 820 is configured to adjust the RF oscillating signal and / or at least one of the DC current and DC voltage based on a feedback signal received directly from the AFPD 840. Tuning network 830 may include a voltage-current tuner for adjusting the phase difference between the voltage and current of the tuned RF signal based on measurement data from AFPD 840 when the power switching device is in the amplification state. A suitable voltage-current tuner is described in more detail with reference to FIG6 . According to FIG32 , the voltage-current tuner of tuning network 830 is applied to the signal connection leading out of device 800 . When power is transmitted downward in FIG32 , the voltage-current tuner thereby functions as a tuner. The voltage-current tuner can be transparent to power transmitted in the opposite, upward direction through device 800 in FIG32 , making power transmission circuit device 800 bidirectional. In certain embodiments, tuning network 830 can transmit the tuned RF power signal to AC load / source 900, which can be transmitter resonators 30 and 30″, as described with reference to FIG6 and FIG19A , FIG27A , and FIG27B . When the AC load / source 900 is this dual-peak emitter resonator, a voltage-current tuner can be used to adjust the ratio of the electric field to the magnetic field, as described with reference to FIG. 6 . The sealed power transmission circuit device 800 may further include a power management (PM) circuit 860 within the sealed interior, in wired data communication with the controller 880 and in wired electrical communication between the MPS 810 and a DC source / load 700 external to the sealed device 800. The PM circuit 860 is configured to impedance match the MPS 810 to the external DC source / load 700 and to adjust the DC power transferred between the MPS 810 and the DC source / load 700 based on measurement data transmitted to the controller by the AFPD 840. In other embodiments not shown in FIG. 32 , the PM circuit 860 may be configured to adjust the DC power transferred between the MPS 810 and the DC source / load 700 based on feedback signals received directly from the AFPD 840 and / or the VID 850. Note again that DC power can be transferred in both directions via PM circuit 860 between MPS 810 and DC source / load 700. Note also that a convention is maintained herein whereby DC source / load 700 is described as "source / load," while the external AC load / source 900, which delivers AC power to the tuning network, is described as "load / source." This emphasizes the following: when DC source / load 700 functions as a DC source, AC load / source 900 functions as a load for converting the power into AC power, and vice versa. The arrows depicted near and parallel to the connector in FIG. 32 indicate the path and direction of power transfer circuitry 800 when MPS 810 is in either its amplifying or rectifying state. When MPS 810 is in the amplifying state, power flows downward through FIG. 32; when MPS 810 is in the rectifying state, power flows upward through FIG. 32. The sealed power delivery circuit device 800 may further include a voltage / current detector (VID) 850 within the sealed enclosure, in wired data communication with a controller 880. This voltage / current detector is configured to determine the DC voltage and DC current transmitted between the MPS 810 and the PM circuit 860. When the MPS 810 is in an amplifying state, the power delivery circuit device 800 can be adjusted based on the measurements of VID 850, so that the device 800 presents an equivalent DC load to the DC source / load 700, thereby allowing maximum power to be extracted from the DC source / load 700. This adjusts the DC voltage at at least one DC terminal of the MPS device 810. When the MPS 810 is in a rectifying state, the power delivery circuit device 800 can be adjusted based on the measurements of VID 850, so that the device 800 presents an equivalent DC source impedance to the DC source / load 700, thereby allowing maximum power transfer from the device 800 to the DC source / load 700. The DC voltage at the wired connection between the device 800 and the DC source / load 700 is thereby adjusted. The sealed power transmission circuit device 800 may further include a memory 870 within the sealed interior for wired data communication with the controller 880, the AFPD 840, and the VID 850, wherein the memory 870 is configured to receive and store signal data from the two detectors 840 and 850 and provide signal data from the two detectors 840 and 850 to the controller 880. The memory 870 is capable of storing the complete state of the device 800 for a series of consecutive instants in time. The tuning network may further include one or more of a compensation network, a matching network, and a filter. The compensation network 26E, the matching network 26D, and the filter 26C of FIG6 are suitable for this purpose, and the selection is not limited to the devices of FIG6. The sealed power delivery circuit device 800 may include a controller 880 within the sealed interior. In other embodiments, the sealed power delivery circuit device 800 may employ an external controller having suitable input / output facilities to communicate data with the various circuits incorporated within the sealed interior of the device 800, and suitable software or firmware may be programmed into the controller to perform all of the control process steps described above. The sealed power transfer circuit device 800 may further include at least one communication circuit 890 that operates on one or more of Bluetooth, WiFi, Zigbee, and cellular technologies to bidirectionally transmit information between the controller 880 and devices external to the sealed power transfer circuit device 800. The at least one communication circuit 890 may be configured for bidirectional wired communication with one or more suitable antennas 894. While one or more antennas 894 may be located within the sealed interior of the device 800, it is typically more efficient to locate such antennas outside the device 800. One or more of the external devices may be other power transfer circuit devices, including, for example, another device 800, and one or more of the other devices may form part of a collective power transfer system as described above in other embodiments (e.g., FIG. 1 ). The PFDCA circuit can be configured to adjust the duty cycle of the RF oscillator signal based on measurements taken by the AFPD 840 and the VID 850. In some embodiments, information regarding the measurements can be communicated to the controller 880 and from there to the PFDCA circuit 820, which then adjusts the duty cycle of the RF oscillator signal based on the received information. In other embodiments, not shown in FIG32 , feedback signals can be directly transmitted from the AFPD 840 and the VID 850 to the PFDCA circuit 820, which then adjusts the duty cycle of the RF oscillator signal based on the received feedback signals. By varying the duty cycle of the RF oscillator signal, the PFDCA circuit 820 can adjust the direction of power flow through the device 800. As power flows from the DC source / load 700 through the device 800 to the AC load / source 900, the PFDCA circuit 820 can thereby adjust the DC power delivered from the source / load 700 to the device 800 and the AC power delivered from the device 800 to the AC load / source 900. As power flows from AC load / source 900 through device 800 to DC source / load 700 , PFDCA circuit 820 may thereby regulate the AC power delivered by C load / source 900 to device 800 and the power delivered by device 800 to DC source / load 700 . Controller 880 can perform two-way wired communication with external devices and circuits 898 (labeled "Ext." in FIG. 32 ) disposed outside the sealed interior of device 800. For example, and without limitation, this wired communication can be used to exchange data with respect to a system in which device 800 may be incorporated or to supply system clock synchronization signals to controller 880. 6 and 7 , the sensors and detectors 24A, 24B, 24C, and 24D may be effectively disposed outside of the sealed interior of the device 800 . Bidirectional power transmission circuit device 800 can also be effectively used to transmit and / or receive information via a power channel passing through device 800, using the mechanisms explained above with reference to Figures 6 and 7. The power channel physically extends from the wired connection between DC source / load 700 and PM circuit 860, through PM circuit 860, VID 850, MPS device 810, and tuning network 830, to AC load / source 900. Along the physical power channel, PM circuit 860, MPS device 810, and tuning network 830 are all under the control of controller 880, which controls MPS device 810 via PFDCA circuit 820. The controller can modulate the RF power signal in tuning network 830 and / or in MPS device 810 itself. The controller can also be configured to sense modulation of the DC voltage between PM circuit 860 and DC source / load 700. This allows information to be modulated onto the RF power signal, the tuned RF power signal, and / or the aforementioned DC voltage, and thereby transmitted to other devices external to the device 800. These other devices may include other bidirectional power transmission circuit devices 800. Information can be modulated onto the RF power signal, the tuned RF power signal, and / or the aforementioned DC voltage in digital or analog form. In other embodiments, the information can be modulated onto a frequency different from the frequency of the power transmission. In other embodiments, the information can be modulated onto a harmonic of the frequency of the power signal. In yet further embodiments, the frequency of the RF power signal can be a harmonic of the frequency of the signal onto which the information is modulated. In the foregoing, it has been explained how the tuning network 830 subsystem can be used as a suitable modulator. Having described above how device 800 can be reconfigured between transmitter and rectifier modes, and how the power path can be modulated, it is clear that device 800 can function as a full-duplex transmit-receive system, transmitting information in both directions. When two devices 800 are employed in transmitter module 20 and receiver module 40 of FIG. 1 , system 10 of FIG. 1 can include additional secondary sides similar to secondary side 14 of FIG. When additional secondary sides 14 are present, the arrangement described above allows information to be transmitted between each secondary side 14, and thereby to primary side 12. By using device 800 of FIG. 32 , the same full-duplex transmit-receive configuration can be employed between transmitter module 20″ and receiver module 40″ employed in the system of FIG. 19A and FIG. This is also true for the systems shown in FIG. 20A-22B and FIG. 27A-28B . The information transmitted in the manner described herein may include, without limitation, the operating mode of the MPS device 810, the number and type of other devices 810, surrounding object sensor information, and load status monitoring information including, for example, battery charge status, load voltage, and load current. The electronic circuitry of the sealed bidirectional power transfer circuit device 800 can be implemented using a variety of device fabrication technologies, including, without limitation, as multiple discrete devices suitable for use on a circuit board, as a hybrid circuit (where devices fabricated in separate sections of semiconductor material can be bonded or mounted to a suitable substrate material), as a flip-chip configuration with active-side-down bonding to one or more individual devices on a silicon-based circuit, or as a single monolithic integrated circuit device. FIG33 illustrates a flip-chip arrangement in which the bidirectional power transfer circuit device 800 of FIG32 includes a multi-terminal power switching (MPS) device 810 implemented in a separate semiconductor die and then flip-chip mounted via solder bumps on pads 808. For example, without limitation, the MPS device 810 can be fabricated as a discrete higher-power device in a wide-bandgap semiconductor die. Pads 808 are formed on a silicon wafer 801, which also contains the balance of the subsystems of the device 800 of FIG32, all monolithically integrated within the silicon wafer 801. The two pads 806 are used for connection to the DC source / load 700 and AC load / source 900 shown in Figure 32. The pad 802 is used to connect the controller 880 and the communication circuit 890 to devices and antennas external to the device 800. In one particular embodiment as shown in FIG. 34A , the electronic circuitry of a sealed bidirectional power transfer circuit device 800 may be implemented within a single silicon single crystal wafer 812 in conjunction with at least one photovoltaic cell 814 serving as the DC source / load 700 of FIG. 32 . In yet another embodiment, further explained with reference to FIG34B , as described above, the electronic circuitry of the sealed bidirectional power transfer circuit device 800 can be implemented within a single silicon single crystal wafer 812, along with at least one photovoltaic cell 814 serving as the DC source / load 700 of FIG32 , and a resonator structure 180′ of the type described with reference to FIG2B and described in greater detail with reference to FIG2A through FIG5 , serving as the AC load / source 900 on one surface of the silicon single crystal wafer 812. An antenna 894 for Bluetooth, WiFi, Zigbee, and cellular technologies can also be integrated onto the same single silicon single crystal wafer. Antenna 894 is not shown in FIG34B . In FIG34A and FIG34B , connection 818 connects resonator 180′ to the tuning network 830 of device 800. Resonator 180′ can serve as a heat sink or heat dissipator for heat generated in device 800 or absorbed by photovoltaic cell 814. To this end, the resonator 180' may employ air as both a dielectric and a coolant fluid. In other embodiments, the DC load 70″ of Figures 19A and 19B can be replaced with an AC load 70″ in both cases, as shown in Figures 35A and 35B, respectively. The remainder of the systems 10″ and 410 of Figures 35A and 35B can be the same as the systems 10″ and 410 of Figures 19A and 19B. The oscillator 26A″ of Figures 19A and 19B can be set to the frequency and phase required by the AC load 70″ of Figures 19A and 19B. In other embodiments, the transmitter controller 22″ can be programmed to set the oscillator 26A″ to the frequency and phase required by the AC load 70″. In yet other embodiments of the system of Figures 35A and 35B, the AC load 70'' can be a power grid, and the system of Figures 35A and 35B is configured to deliver power to that grid. In this grid supply configuration, it is important to control the frequency, phase, and voltage level of the signal fed by the system of Figures 35A and 35B to the power grid 70'' in question. To this end, the information feedback mechanism described above can be used to transmit information regarding the desired frequency, phase, and voltage level of the power grid back to the transmitter controller 22''. This information can be in digital or analog form. In certain embodiments of the wired system of Figure 35B, an additional signal line (not shown to avoid clutter) can be connected from the AC power grid 70''' to the transmitter controller 22'' or directly to the oscillator 26A'', allowing the transmitter module 20'' to directly track the frequency and phase of the AC load 70'', thereby imposing the constraints required by the power grid 70'' on the output signal of the system of Figure 35B. These constraints may include modulating the output signal of the load management system 46E'' to meet the requirements of the grid 70''. The modulation may be performed at a frequency equal to the grid frequency and at a phase and voltage level at which power is delivered to the grid 70''. FIG36 illustrates an embodiment of the system of FIG32 , in which the AC load / source 900 of FIG32 is an AC grid 900 ′. In this embodiment, as with the systems of FIG35A and FIG35B , information regarding the grid's required frequency, phase, and voltage level can be transmitted back to controller 880 . This allows controller 880, via phase, frequency, and duty cycle adjustment (PFDCA) circuit 820, to adjust the signal at the control terminals of MPS device 810 to meet the power delivery requirements imposed by grid 900 ′. These requirements can include modulating the output signal of tuning network 830 to meet the requirements of grid 70 ′′. This modulation can be performed at a frequency equal to that of the grid and at a phase and voltage level that delivers power to grid 70 ′′. While inherently bidirectional, the system of FIG3 can, with this arrangement, be used as a means of delivering power to an AC grid. Returning now to Figures 20A and 20B, Figures 21A and 21B, and Figures 22A and 22B, each solar cell 420 can be equipped with a sensor to determine the operating status of the solar cell 420. The operating status can include, without limitation, power level, voltage level, current level, temperature, and other performance parameters. This information regarding the operating status can be transmitted to the receiver module 40" via the transmitter module 20" associated with the solar cell 420. The operating status of the transmitter module 20" can be similarly sensed and transmitted to the receiver module 40" via the transmitter module 20". Referring to Figures 33 and 34A and 34B, suitable sensors can also sense the performance parameters of the sealed bidirectional power transmission circuit device 800 and the multi-terminal power switching (MPS) device 810. Transmission of load information via the MPS device 810 has already been described. Information regarding the performance parameters of devices 800 and 810 can similarly be transmitted throughout the system. Figures 37A and 37B illustrate two configurable bidirectional power transfer systems for transferring power from a DC source, according to certain embodiments. Figures 37C and 37D illustrate various embodiments of configurable power transfer systems for transferring power between a DC source and a variable load. The variable load can be an AC load (in the case of both Figures 37A and 37B ), a DC load ( Figure 37B ), or a load carrying a mix of AC and DC power ( Figure 37B ). FIG37A shows a system 950 for transmitting power between a DC source 1028 and an AC load / source 1070, the system being configured to transmit power from the DC source to an AC grid operating at a typical line frequency of approximately 50 Hz or approximately 60 Hz. System 950 can also be configured to transmit power in the reverse direction. As with FIG19A , FIG19B , FIG35A , and FIG35B , system 950 of FIG37A is based on controlled functionality of self-synchronous RF rectifiers / amplifiers 1025A and 1025B, which can be reconfigured between amplifier mode and rectifier mode. These devices 1025A and 1025B can be the same as or similar to the self-synchronous RF rectifier / amplifier 26B of FIG6 and FIG8 and the rectifier 46D of FIG7 and FIG9 . Devices 1025A and 1025B can comprise switched-mode self-synchronous RF rectifiers / amplifiers. In a first embodiment, a centralized controller 1080 is employed. Controller 1080 may include protection circuitry for the system. In other embodiments, distributed controllers may be used for the same purpose. When power is being transferred from DC source / load 1028, devices 1025A and 1025B are placed in an amplifying mode, and their switching action is driven by a switching signal provided by a high-frequency switching signal generator 1024. High-frequency switching signal generator 1024 provides the switching signal frequency that drives devices 1025A and 1025B, controls the switching duty cycle of devices 1025A and 1025B, and ensures that the switching patterns of devices 1025A and 1025B have a controlled mutual phase and pulse width relationship. In the systems of Figures 37A and 37B, high-frequency switching signal generator 1024 supplies a switching signal to each of devices 1025A and 1025B. In more general systems (such as those described below with respect to Figures 37C and 37D), a high-frequency switching signal generator similar to high-frequency switching signal generator 1024 can provide switching signals to multiple pairs of self-synchronous RF rectifier / amplifiers. The number of high-frequency switching signal generators used in any embodiment can vary. For example, one high-frequency switching signal generator can provide switching signals to one pair of self-synchronous RF rectifier / amplifiers. One high-frequency switching signal generator can provide switching signals to multiple pairs of self-synchronous RF rectifier / amplifiers. The high frequency switching signal generator 1024 can be controlled by the controller 1080 to utilize a first frequency of f A The first switching signal drives the differential self-synchronous RF rectifier / amplifier 1025A (in amplifier mode). At the same time, the high frequency switching signal generator 1024 can be controlled by the controller 1080 to use the second frequency f B The second switching signal of drives the differential self-synchronous RF rectifier / amplifier 1025B (in amplifier mode), where: B = f A + ∆f … (Equation 1), In Equation 1, the difference frequency ∆f between the frequencies of the second switching signal and the first switching signal is twice the frequency at which the power to be transferred is to be supplied to the AC load / source 1070 . In embodiments where the AC load / source 1070 is not carrying a power signal in the absence of the system 950, the frequency f B and f AAnd thereby the difference frequency ∆f can be simply set in or by the high-frequency switching signal generator 1024. Frequency f B and f A may differ from each other by a difference frequency ∆f that is twice the frequency of the power signal intended to be injected into the AC load / source 1070. In some embodiments, the frequency f B and f A It can be set in the high frequency switching signal generator 1024 by the controller 1080 based on design choice. In other embodiments where there is an existing AC power signal in the AC load / source 1070 (such as in a residential grid), the operating frequency f of the AC load / source 1070 may be sensed. L The frequency f of the switching signal is set in the high frequency switching signal generator 1024. B and f A , and the frequency f is converted to L A reference signal is transmitted to the high-frequency switching signal generator 1024. In this specification, the term "load information circuit" is used to describe a section of the circuit. To distinguish this additional circuit portion from the circuit portion used when there is no existing power signal in the AC load / source 1070, this load information circuit and its components are shown in dashed lines in Figure 37A. The direction of reference signal flow in this circuit is indicated by the arrows in Figure 37A. In some cases, an optional isolator system 1090 may be included for certain areas. When the load is not carrying a power signal, certain areas may need to be isolated from the AC load / source 1070 by adjustment. The optional isolator system 1090 may include an air gap. Those skilled in the art will recognize how to use isolators to provide data and timing signals, and the details are not described herein. In other embodiments, instead of using a reference signal, information about at least one of the DC level, frequency, and phase of the power signal in the load can be transmitted to the high-frequency switching signal generator 1024. The high frequency switching signal generator 1024 can make the sensed frequency f L Multiply to determine the frequency f B With f A The required difference frequency ∆f between the two, and the resulting frequency f B and f A In this embodiment, the operating frequency f of the sensing AC load / source 1070 is applied to the switching signal to the devices 1025A and 1025B. L The process of transmitting the signal to the high frequency switching signal generator 1024 and making the operating frequency f L The multiplication can all be performed under the control of controller 1080. To avoid cluttering Figure 37A, the control lines extending from controller 1080 to the devices it senses or controls (including devices 1025A and 1025B) are not shown. It should be noted that the frequency f of the switching signal B and f A The difference must only be ∆f=2f ...

Claims

1. A power transmission system for transmitting power between a direct current (DC) source and a variable load, the system comprising: A first self-synchronizing RF rectifier / amplifier and a second self-synchronizing RF rectifier / amplifier, configured to extract a first high-frequency power signal and a second high-frequency power signal from the DC source at a first frequency and a second frequency, respectively; a high-frequency power link system configured to receive and mix the first high-frequency power signal and the second high-frequency power signal to generate a transmitted power signal; and a power signal conversion circuit that communicates with the high-frequency power link system and the variable load, and is configured to generate an output power signal based at least in part on the transmitted power signal, and supply the output power signal to the variable load.

2. The power transmission system as described in claim 1, further comprising: A high-frequency switching signal generator is configured to supply a first switching signal and a second switching signal to a first self-synchronizing RF rectifier / amplifier and a second self-synchronizing RF rectifier / amplifier at their respective first and second frequencies, and to establish and control a mutual phase relationship between the first switching signal and the second switching signal.

3. The power transmission system as described in claim 2, wherein, The power signal conversion circuit includes: a switching mode rectifier configured to receive the transmitted power signal from the high-frequency power link system and rectify the transmitted power signal to generate a rectified power signal; and a demultiplexing circuit configured to receive the rectified power signal from the switching mode rectifier and demultiplex the rectified power signal to generate the output power signal.

4. The power transmission system as described in claim 3, wherein, The first self-synchronizing RF rectifier / amplifier and the second self-synchronizing RF rectifier / amplifier are configured to operate in a rectification mode, and the switching mode rectifier is configured to operate in a normally open mode, thereby allowing power to be drawn from the variable load and delivered to the DC source via the power signal conversion circuit and the high-frequency power link system.

5. The power transmission system as described in claim 2, wherein: The first frequency and the second frequency are the same frequency; and the first switching signal and the second switching signal have a mutual phase difference that can be adjusted by the high-frequency switching signal generator.

6. The power transmission system as described in claim 5, wherein, The high-frequency switching signal generator is configured to adjust the phase difference between the first switching signal and the second switching signal based on a DC level in the variable load, thereby generating the transmitted power signal from the high-frequency power link system as a DC signal that is adjusted accordingly in terms of amplitude.

7. The power transmission system as described in claim 5, wherein, The high-frequency switching signal generator is configured to modulate the phase difference between the first switching signal and the second switching signal at a phase modulation frequency derived from a power signal in the variable load, based at least in part on a modulation function, thereby generating the transmitted power signal from the high-frequency power link system as an alternating current (AC) power signal modulated at the frequency of the power signal in the variable load.

8. The power transmission system as described in claim 2, wherein, The first frequency and the second frequency differ by a frequency difference.

9. The power transmission system as described in claim 8, wherein, The high-frequency switching signal generator is configured to determine the first frequency and the second frequency, and to set the difference frequency to multiply the frequency of the power signal in the variable load.

10. The power transmission system as described in claim 8, wherein: The high-frequency power link system is configured to generate the transmitted power signal at the differential frequency; and the power signal conversion circuit is configured to supply the output power signal to the variable load at the frequency of the power signal in the variable load.

11. The power transmission system as claimed in claim 1, wherein, The high-frequency power link system includes a wireless power link.

12. The power transmission system as claimed in claim 11, wherein, The wireless high-frequency power link system includes a dual-peak wireless high-frequency power link system.

13. The power transmission system as claimed in claim 1, wherein, The high-frequency power link system includes a wired high-frequency power link.

14. A method for transmitting power between a direct current (DC) source and a variable load, the method comprising: A first high-frequency power signal and a second high-frequency power signal are extracted from the DC source at a first high-frequency frequency and a second high-frequency frequency, respectively, via a corresponding first self-synchronizing RF rectifier / amplifier and a second self-synchronizing RF rectifier / amplifier; the first high-frequency power signal and the second high-frequency power signal are received and mixed in a high-frequency power link system to generate a transmitted power signal; an output power signal is generated at least partially based on the transmitted power signal in a power signal conversion circuit that communicates with the high-frequency power link system and the variable load; and the output power signal is supplied to the variable load.

15. The method of claim 14, further comprising: A high-frequency switching signal generator that communicates with the first self-synchronizing RF rectifier / amplifier and the second self-synchronizing RF rectifier / amplifier generates a first switching signal and a second switching signal at their respective first high-frequency and second high-frequency frequencies; and establishes and controls a mutual phase relationship between the first switching signal and the second switching signal in the high-frequency switching signal generator.

16. The method of claim 14, further comprising: The system receives the transmitted power signal from the high-frequency power link system and rectifies the transmitted power signal in all mode-switching rectifiers of the power signal conversion circuit; and receives the rectified power signal from the mode-switching rectifier and expands the rectified power signal in a demultiplexing circuit of the power signal conversion circuit.

17. The method of claim 16, further comprising: The first self-synchronizing RF rectifier / amplifier and the second self-synchronizing RF rectifier / amplifier are set to a rectification mode; the switching mode rectifier is set to a normally open mode to extract power from the variable load; and the extracted power is transmitted to the DC source via the power signal conversion circuit and the high-frequency power link system.

18. The method according to claim 15, wherein, Transmitting the power signal in this high-frequency power link system includes wirelessly transmitting the power signal.

19. The method according to claim 18, wherein, In this high-frequency power link system, the wireless transmission of the power signal includes both dual-peak and wireless transmission of the power signal.

20. The method according to claim 15, wherein, Transmitting the power signal in this high-frequency power link system includes transmitting the power signal via a wired connection.

21. The method according to claim 15, wherein, The first high-frequency frequency and the second high-frequency frequency of the first switching signal and the second switching signal are the same frequency; and the first switching signal and the second switching signal have a mutual phase difference that can be adjusted by the high-frequency switching signal generator.

22. The method as described in claim 21, further comprising: The phase difference between the first switching signal and the second switching signal is adjusted based on a DC level in the variable load to generate the transmitted power signal from the high-frequency power link system as a DC signal that is adjusted accordingly in terms of amplitude.

23. The method of claim 21 further comprises, at least in part, modulating the phase difference between the first switching signal and the second switching signal at a phase modulation frequency derived from a power signal in the variable load at a modulation function, so as to generate the transmitted power signal from the high-frequency power link system as an alternating current (AC) power signal modulated at the frequency of the power signal in the variable load.

24. The method of claim 15, further comprising: Determine the first high-frequency frequency and the second high-frequency frequency of the corresponding first switching signal and second switching signal; And set the differential frequency to be equal to twice the frequency of the power signal in the variable load.

25. The method of claim 24, further comprising: The transmitted power signal is generated from the high-frequency power link system at this difference frequency. And at that frequency of the power signal in the variable load, the output power signal is supplied to the variable load.

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