A frequency-agile directional backwave microwave power transmission system based on code division multiplexing reception

Abstract

The application provides a frequency-agile direction backtracking microwave power transmission system based on code division composite reception, and belongs to the technical field of microwave power transmission. The system comprises a phased array microwave transmitting end and a microwave power receiving end. The transmitting end is integrated with a receiving antenna array, a guide beacon receiving and processing array, a data processing and control unit, a microwave power transmitting channel array and a transmitting antenna array. The receiving end is configured with a beacon generating circuit, a transceiving antenna and a microwave rectifying circuit. The application adopts code division modulation and radio frequency composite architecture, combines multiple guide signals into two channels of reference and composite, performs frequency down conversion, digitization and complex correlation despreading, accurately extracts the phase difference of array elements, generates amplitude and phase control words to realize frequency-agile beam adaptive backtracking. The system relies on frequency-agile transceiving to enhance anti-interference, and the double-channel design simplifies hardware and reduces cost. The system has the characteristics of high backtracking accuracy, adaptive dynamic and static targets and multi-target time-sharing power transmission, and is suitable for long-distance wireless power transmission scenes such as unmanned aerial vehicle clusters and space solar power stations.

Description

Technical Field

[0001] This invention belongs to the field of microwave power transmission technology and relates to a different frequency directional backtracking microwave power transmission system based on code division multiplexing reception. It is suitable for scenarios such as power supply for UAV swarms, space solar power stations, and long-distance wireless power transmission for IoT devices. Background Technology

[0002] The core technology of microwave wireless power transmission lies in the high-precision directional aiming of the microwave beam at the receiver. If the beam direction is off, it will not only cause serious spatial energy loss and significantly reduce wireless power transmission efficiency, but also cause the spread of useless electromagnetic radiation, bringing electromagnetic environment safety hazards.

[0003] Early microwave beam pointing primarily employed mechanical servo aiming, relying on mechanical rotation mechanisms to adjust the antenna's attitude and achieve beam orientation. This approach suffers from high operational complexity and significant beam response delays, making it unsuitable for real-time tracking of high-speed moving targets. Furthermore, it is not conducive to the engineering deployment of large arrays, and its tracking accuracy and automation levels are limited. Consequently, it has been gradually replaced by modern intelligent beam control technology.

[0004] Directional backtracking antennas, relying on the phase conjugate principle, can autonomously achieve adaptive beam alignment with the guiding beacon source without prior detection of the incoming wave's azimuth. They possess advantages such as eliminating the need for complex algorithm adjustments and strong real-time performance, and have become the mainstream technology system in the field of microwave beam control. Their typical implementations are mainly divided into three categories: One approach is the Van Atta passive array, which connects symmetrically arranged antenna elements via equal-length transmission lines. It features a simple structure, low profile, and ease of integration, allowing for the integration of low-power amplifier modules for microwave power transmission applications. However, this array can only achieve plane wave backtracking and cannot adapt to near-field non-planar wave radiation scenarios. Furthermore, the array requires a strictly planar layout, resulting in poor compatibility with curved conformal carriers. Additionally, the equal-length transmission line wiring limits the array's size, and the built-in amplifier's gain is limited, failing to meet the application requirements of high-power, long-distance microwave wireless power transmission.

[0005] The second is an analog phase conjugate phased array system, which achieves phase conjugation based on the heterodyne mixing principle and combines it with an antenna array to complete beamforming. This system is implemented with a pure analog circuit architecture, which has a fast beam response speed and does not require complex digital signal processing; however, it has problems such as insufficient isolation between the transmitting and receiving channels and inconsistent amplitude and phase of the channels, which can easily induce beam pointing deviation, and has weak anti-interference capability and does not have the ability to track and supply power to multiple targets simultaneously.

[0006] The third option is a digital phased array system with different frequencies for both transmission and reception. This system down-converts the received guidance signal to baseband, performs digital phase conjugation processing, and then reconstructs the transmit beam. This effectively compensates for the shortcomings of analog phased arrays in terms of isolation, amplitude and phase error, anti-interference, and multi-target adaptation. However, this solution has a complex hardware architecture. As the antenna array scales up, the design complexity and development cost of the channel links and digital processing units will increase dramatically, limiting its practicality for engineering implementation. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide a microwave power transmission system based on code division multiplexing reception with different frequencies for direction backtracking. Under the condition of different frequencies for transmission and reception, high-precision direction backtracking is achieved through a simplified receiving channel architecture, thereby reducing system cost and complexity.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A cross-frequency directional backtracking microwave power transmission system based on code division multiplexing reception, the system comprising a phased array microwave power transmitter and a microwave power receiver; The phased array microwave power transmitter includes a receiving antenna array, a guiding beacon receiving and processing array, a data processing and control unit, a microwave power transmission channel array, and a transmitting antenna array. The receiving antenna array consists of multiple receiving array elements arranged according to a preset spatial geometry, and is used to receive microwave signals from space guidance beacons. The guidance beacon receiving and processing array is signal-connected to the receiving antenna array and includes N parallel pseudo-code modulation radio frequency front-ends, power combiners, receiving local oscillators, reference down-conversion branches, and composite down-conversion branches. Each pseudocode modulation RF front-end includes a bandpass filter, a low-noise amplifier, and a phase-shift keying modulator connected in series. The input of the bandpass filter is connected to the corresponding receiving array element and is used to filter out out-of-band interference signals, especially downlink power microwave signals. The low-noise amplifier is used to amplify the filtered weak guide beacon signal with low noise. The phase-shift keying modulator is connected to the low-noise amplifier and receives the corresponding pseudocode, which is used to perform phase-shift keying modulation on the amplified guide beacon signal so that each signal carries a different code division identifier. Among them, the first pseudocode modulation RF front-end serves as a reference channel and receives pseudocode C1; the second to Nth pseudocode modulation RF front-ends receive pseudocodes C2, C3, ... respectively, serving as composite channels. The multiple input terminals of the power combiner are respectively connected to the output terminals of the second to Nth pseudocode modulation radio frequency front-end, which are used to combine the N-1 pseudocode modulation radio frequency signals and output a composite radio frequency signal. The receiving local oscillator is used to generate a receiving local oscillation signal, and outputs it to the reference down-conversion branch and the composite down-conversion branch respectively; The reference downconversion branch includes a mixer, an intermediate frequency filter, an intermediate frequency amplifier, and an analog-to-digital converter connected in series. The RF input terminal of the mixer is connected to the output signal of the first pseudo-code modulation RF front end, and the local oscillator input terminal is connected to the receiving local oscillator. The reference RF signal and the local oscillator signal are mixed. The mixed output signal is filtered by the intermediate frequency filter to remove noise, and then amplified by the intermediate frequency amplifier to form the reference branch analog intermediate frequency signal. Finally, it is converted into the reference branch digital intermediate frequency signal by the analog-to-digital converter.

[0009] The composite downconversion branch includes a mixer, an intermediate frequency filter, an intermediate frequency amplifier, and an analog-to-digital converter cascaded in sequence. The RF input terminal of the mixer is connected to the output terminal of the power combiner to output a signal, and the local oscillator input terminal is connected to the receiving local oscillator to perform a mixing process between the composite RF signal and the local oscillator signal. The mixed output signal is filtered by the intermediate frequency filter to remove noise, and then amplified by the intermediate frequency amplifier to form the composite branch analog intermediate frequency signal. Finally, it is converted into the composite branch digital intermediate frequency signal by the analog-to-digital converter.

[0010] The data processing and control unit includes two quadrature digital downconverters, a complex correlation despreader, a phase difference detector, an amplitude and phase control word generator, and a pseudocode generator; The input terminals of the two quadrature digital downconverters are respectively connected to the output terminals of the reference downconverter branch and the composite downconverter branch, for outputting the reference complex baseband signal and the composite complex baseband signal respectively. The two inputs of the complex correlation despreader are respectively connected to the outputs of the two orthogonal digital downconverters; one output of the pseudocode generator is connected to the pseudocode input of the complex correlation despreader, and is used to generate and output pseudocodes C1, C2, C3...; the other output of the pseudocode generator is connected to each phase shift keying modulator in the guidance beacon receiving and processing array. The input terminal of the phase difference detector is connected to the output terminal of the complex correlation despreader, and is used to extract the phase difference information of each signal relative to the reference branch signal; The input terminal of the amplitude and phase control word generator is connected to the output terminal of the phase difference detector, and is used to generate the amplitude control word and phase control word required for each transmission channel according to the phase difference information. The microwave power transmission channel array includes a transmission local oscillator, a power divider, and N parallel amplitude- and phase-adjustable transmission front-ends; The transmitting local oscillator is used to generate a transmitting local oscillation signal; the input terminal of the power divider is connected to the transmitting local oscillator and is used to distribute the transmitting local oscillation signal into N channels; Each of the amplitude- and phase-adjustable transmitting front-ends includes a digitally controlled attenuator, a digitally controlled phase shifter, and a power amplifier connected in series. The digitally controlled attenuator receives an amplitude control word from the data processing and control unit for amplitude modulation. The digitally controlled phase shifter receives a phase control word from the data processing and control unit for phase modulation. The power amplifier amplifies the power of the amplitude- and phase-modulated signal. The transmitting antenna array consists of multiple transmitting array elements, and each transmitting array element is connected to one of the outputs of the microwave power transmitting channel array to radiate microwave power signals into space. The microwave power receiver includes a guidance beacon generation circuit, a transmitting antenna, a receiving antenna, and a microwave rectifier circuit. The guidance beacon generation circuit generates an uplink guidance beacon signal. The transmitting antenna radiates the uplink guidance beacon signal to the phased array microwave power transmitter. The receiving antenna receives a downlink power microwave signal from the transmitting antenna array. The microwave rectifier circuit converts the received downlink power microwave signal into a DC output. The operating frequency of the receiving antenna array f 1 and the operating frequency of the transmitting antenna array f Unlike 2, the transmitting antenna array and the receiving antenna array can be set separately, or they can be a dual-frequency antenna array with the same aperture; the amplitude and phase control word output by the data processing and control unit is applied to the digitally controlled phase shifter and the digitally controlled attenuator, so that the transmitting beam is pointed in the direction of the guiding beacon signal.

[0011] The beneficial effects of this invention are as follows: 1) Strong anti-interference capability across frequencies: The receiving guidance beacon and the transmitting power microwave use different frequencies, respectively. f 1 and f 2. This facilitates the use of bandpass filters to suppress interference from downlink power signals on the guidance signals; simultaneously, by multiplying the frequency ratio in the digital domain... k = f 2 / f 1. Implement inter-frequency phase mapping to ensure consistency of backtracking angle under inter-frequency transmission and reception conditions.

[0012] 2) Simplified hardware and low cost: By using orthogonal coding and RF domain power combining technology, N array element signals are combined into a small number of channels (such as 1 reference + 1 composite), which significantly reduces the number of receiving channels. Only a small number of ADCs are needed to obtain the phase information of all array elements, avoiding the N independent ADC sampling architecture required by traditional digital beamforming, and greatly reducing hardware complexity and system cost.

[0013] 3) High phase backtracking accuracy: It adopts a reference-composite dual-channel architecture. The reference branch directly processes the reference array element signal, and the composite branch processes the synthesized signal. Through complex correlation operation combined with local composite pseudo-random codes C1·C2, C1·C3..., the phase difference of each array element relative to the reference array element is extracted respectively. This effectively avoids the amplitude and phase inconsistency problem of multiple independent receiving links, improves the phase detection accuracy, and theoretically can achieve accurate direction backtracking.

[0014] 4) Adaptive dynamic and static modes: Combining RF domain compositing and digital domain despreading, the processing link has low latency. For high-speed moving targets, it can continuously receive guidance signals and update the amplitude and phase control word in real time to ensure dynamic and accurate beam pointing. For stationary targets, the system only needs to complete the phase difference detection and control word calculation once in the initial stage. Then, the amplitude and phase control word is locked and the receiving processing link is turned off. This can maintain beam alignment in the absence of guidance signals, avoid energy waste caused by continuous transmission and reception of guidance signals, and significantly reduce system power consumption.

[0015] 5) Strong multi-target scalability: It supports multi-target applications and can simultaneously receive multiple guidance signals of different frequencies. It generates power beams pointing to different receiving areas through time-division multiplexing, adapting to multi-target scenarios such as UAV swarms.

[0016] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a general block diagram of a microwave power transmission system; Figure 2 Block diagram of the guidance beacon receiving and processing array; Figure 3 Block diagram of the data processing and control unit; Figure 4 This is a block diagram of a microwave power transmission channel array. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0019] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0020] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0021] like Figure 1 As shown, the inter-frequency directional backtracking microwave power transmission system based on code division multiplexing reception proposed in this invention includes a phased array microwave power transmitter 1 and a microwave power receiver 2.

[0022] The phased array microwave power transmitter 1 includes a receiving antenna array 10, a guidance beacon receiving and processing array 11, a data processing and control unit 12, a microwave power transmitting channel array 13, and a transmitting antenna array 14. The receiving antenna array 10 consists of multiple receiving elements 101, 102, 103… arranged in a preset spatial geometry, used to receive spatial guidance beacon microwave signals. The guidance beacon receiving and processing array 11 is signal-connected to the receiving antenna array 10, used to perform code division multiplexing reception and down-conversion processing on the guidance beacon signals output by each receiving element, outputting a reference branch intermediate frequency signal and a composite branch intermediate frequency signal. The input terminal of the data processing and control unit 12 is connected to the output terminal of the guidance beacon receiving and processing array 11, used to perform orthogonal digital down-conversion, complex correlation despreading, phase difference detection, and amplitude and phase control word generation processing on the intermediate frequency signal, outputting an amplitude control word and a phase control word. The input terminal of the microwave power transmission channel array 13 is connected to the control output terminal of the data processing and control unit 12, and is used to perform power distribution, amplitude modulation, phase modulation and power amplification of the transmitted microwave signal according to the amplitude and phase control word to form a direction-backtracking transmission channel. The transmitting antenna array 14 is composed of multiple transmitting array elements 141, 142, 143..., and each transmitting array element is connected to a corresponding output of the microwave power transmission channel array 13, and is used to radiate the direction-backtracked microwave power signal into space.

[0023] The microwave power receiver 2 includes a guidance beacon generation circuit 20, a transmitting antenna 21, a receiving antenna 22, and a microwave rectifier circuit 23. The guidance beacon generation circuit 20 generates an uplink guidance beacon signal; the transmitting antenna 21 is connected to the guidance beacon generation circuit 20 and radiates the uplink guidance beacon signal to the phased array microwave power transmitter 1; the receiving antenna 22 receives a downlink power microwave signal from the transmitting antenna array 14; and the microwave rectifier circuit 23 is connected to the receiving antenna 22 and converts the received downlink power microwave signal into DC output.

[0024] like Figure 2 As shown, the guidance beacon receiving and processing array 11 includes N parallel pseudo-code modulation radio frequency front-ends 111, 112, 113..., a power combiner 114, a receiving local oscillator 115, a reference down-conversion branch 116, and a composite down-conversion branch 117.

[0025] The input terminals of the pseudo-code modulation RF front-ends 111, 112, 113... are respectively connected to the receiving array elements 101, 102, 103... in the receiving antenna array 10, and are used to receive the RF signals of each guiding beacon. The internal structure of each pseudo-code modulation RF front-end is the same. Taking the first pseudo-code modulation RF front-end 111 as an example, it includes a bandpass filter 1111, a low-noise amplifier 1112, and a phase shift keying modulator 1113 connected in series. The input of the bandpass filter 1111 is connected to the receiving array element 101 to filter out out-of-band interference signals, especially downlink power microwave signals. The low-noise amplifier 1112 is connected to the bandpass filter 1111 to amplify the filtered weak guide beacon signal with low noise. The phase-shift keying modulator 1113 is connected to the low-noise amplifier 1112 and receives pseudo-code C1. It is used to perform phase-shift keying modulation on the amplified guide beacon signal using pseudo-code C1, so that the first signal carries the code division identifier. Similarly, the phase-shift keying modulator 1123 in the second pseudo-code modulation RF front-end 112 receives pseudo-code C2, and the phase-shift keying modulator 1133 in the third pseudo-code modulation RF front-end 113 receives pseudo-code C3. Each front-end uses a different pseudo-code to modulate the guide beacon signal of the corresponding channel.

[0026] The multiple input terminals of the power combiner 114 are respectively connected to the output terminals of the pseudo-code modulation radio frequency front-end 112, 113..., and are used to combine N-1 channels of radio frequency signals after pseudo-code modulation to output a composite radio frequency signal, thereby realizing code division multiplexing of multiple signals.

[0027] The receiving local oscillator 115 is used to generate a receiving local oscillation signal and output it to the reference down-conversion branch 116 and the composite down-conversion branch 117, respectively.

[0028] The reference downconversion branch 116 includes a mixer 1161, an intermediate frequency filter 1162, an intermediate frequency amplifier 1163, and an analog-to-digital converter 1164 connected in series. The RF input terminal of the mixer 1161 is connected to the output terminal of the first pseudo-code modulation RF front end (the first reference channel), and the local oscillator input terminal is connected to the receiving local oscillator 115 to perform frequency mixing processing on the reference RF signal and the local oscillator signal. The intermediate frequency filter 1162 is connected to the mixer 1161 and is used to filter out the high-frequency components after mixing. The intermediate frequency amplifier 1163 is connected to the intermediate frequency filter 1162 to amplify the signal, forming the reference branch analog intermediate frequency signal, which is finally converted into the reference branch digital intermediate frequency signal by the analog-to-digital converter 1164 and output to the data processing and control unit 12.

[0029] The composite downconversion branch 117 includes a mixer 1171, an intermediate frequency filter 1172, an intermediate frequency amplifier 1173, and an analog-to-digital converter 1174 connected in series. The RF input terminal of the mixer 1171 is connected to the output terminal of the power combiner 114, and the local oscillator input terminal is connected to the receiving local oscillator 115 to perform frequency mixing of the composite RF signal and the local oscillator signal. The intermediate frequency filter 1172 is connected to the mixer 1171 to filter out the high-frequency components after mixing. The intermediate frequency amplifier 1173 is connected to the intermediate frequency filter 1172 to amplify the signal, forming a composite branch analog intermediate frequency signal, which is finally converted into a composite branch digital intermediate frequency signal by the analog-to-digital converter 1174 and output to the data processing and control unit 12.

[0030] During operation, the guidance beacon radio frequency signal received by the receiving array element 101 is bandpass filtered, low-noise amplified, and pseudo-code phase shift keying modulated by the corresponding pseudo-code modulation radio frequency front-end 111 to form a reference radio frequency signal; the receiving array elements 102, 103... are bandpass filtered, low-noise amplified, and pseudo-code phase shift keying modulated by the corresponding pseudo-code modulation radio frequency front-ends 111, 112, 113... respectively, and then synthesized by the power combiner 114 into a composite radio frequency signal; the reference radio frequency signal undergoes the same down-conversion and digitization processing by the reference down-conversion branch 116 to obtain the reference branch digital intermediate frequency signal; the composite radio frequency signal undergoes amplification, mixing, low-pass filtering, and analog-to-digital conversion by the composite down-conversion branch 117 to obtain the composite branch digital intermediate frequency signal; the two digital intermediate frequency signals are sent to the data processing and control unit 12 for subsequent quadrature digital down-conversion, complex correlation despreading, and phase difference detection processing to extract the spatial phase information of each guidance beacon signal.

[0031] like Figure 3 As shown, the data processing and control unit 12 includes an orthogonal digital down-converter 121, an orthogonal digital down-converter 122, a complex correlation despreader 123, a phase difference detector 124, an amplitude and phase control word generator 125, and a pseudocode generator 120.

[0032] The input terminal of the quadrature digital downconverter 121 is connected to the output terminal of the reference downconverter branch 116, and is used to perform quadrature digital downconversion processing on the reference branch digital intermediate frequency signal to output a reference complex baseband signal containing in-phase and quadrature components.

[0033] The input terminal of the quadrature digital downconverter 122 is connected to the output terminal of the composite downconverter branch 117, and is used to perform quadrature digital downconversion processing on the composite branch digital intermediate frequency signal to output a composite complex baseband signal containing in-phase and quadrature components.

[0034] The two input terminals of the complex correlation despreader 123 are respectively connected to the output terminals of the quadrature digital downconverter 121 and the quadrature digital downconverter 122, and are used to receive the reference complex baseband signal and the composite complex baseband signal. One output terminal of the pseudo-code generator 120 is connected to the pseudo-code input terminal of the complex correlation despreader 123, and is used to generate and output pseudo-codes C1, C2, C3... to the complex correlation despreader 123; the other output terminal of the pseudo-code generator 120 is used to output the pseudo-codes C1, C2, C3... to each phase shift keying modulator in the guiding beacon receiving and processing array 11, as code division modulation identifiers for each receiving channel.

[0035] The input terminal of the phase difference detector 124 is connected to the output terminal of the complex correlation despreader 123, and is used to perform phase detection on each signal after complex correlation despreading, and extract the phase difference information of each signal relative to the reference branch signal.

[0036] The input terminal of the amplitude and phase control word generator 125 is connected to the output terminal of the phase difference detector 124, and is used to calculate and generate the amplitude control word and phase control word required for each transmission channel based on the phase difference information and the direction backtracking algorithm. When the receiving antenna array and the transmitting antenna array are a dual-frequency antenna array with the same aperture, the direction backtracking algorithm introduces a frequency scaling factor in the digital domain. k=f 2 / f 1. Implement phase mapping under different frequency conditions to ensure consistency of direction backtracking angle.

[0037] The amplitude and phase control word generator 125 outputs amplitude control words A1, A2... and phase control words P1, P2, P3... respectively, and sends them to the microwave power transmission channel array 13 to regulate the amplitude and phase of each transmitted signal. The amplitude control words are used to adjust the beam shape of the power beam, and the phase control words are used to adjust the precise pointing of the power microwave beam to the receiving end.

[0038] During operation, the reference branch digital intermediate frequency signal from the reference downconversion branch 116 is converted into a reference complex baseband signal by the quadrature digital downconverter 121, and the composite branch digital intermediate frequency signal from the composite downconversion branch 117 is converted into a composite complex baseband signal by the quadrature digital downconverter 122. The complex correlation despreader 123 performs a complex correlation operation on the reference complex baseband signal obtained by downconversion after modulation with pseudocode C1 from the first receiving channel and the composite complex baseband signals obtained by downconversion after modulation and power synthesis from the second to Nth receiving channels respectively. Then, based on the pseudocodes C1, C2, C3... provided by the pseudocode generator 120, a local composite pseudo-random code C1·C2, C1·C3... is generated, and correlation despreading operation is performed on the complex correlation operation results to obtain the complex correlation baseband signals of the second to Nth complex baseband signals relative to the first reference complex baseband signal.

[0039] The phase difference detector 124 calculates the phase angle of each complex correlation baseband signal to obtain the spatial phase difference of each signal relative to the first reference signal; the amplitude and phase control word generator 125 calculates the amplitude weighting coefficient and conjugate phase compensation of each transmission channel according to the spatial phase difference and the direction backtracking algorithm, generates amplitude control words A1, A2, A3... and phase control words P1, P2, P3..., and outputs them to the microwave power transmission channel array 13.

[0040] like Figure 4 As shown, the microwave power transmission channel array 13 includes a transmission local oscillator 131, a power divider 132, and N parallel amplitude- and phase-adjustable transmission front-ends 133, 134, 135, ...

[0041] The local oscillator 131 is used to generate a local oscillation signal. The input terminal of the power divider 132 is connected to the local oscillator 131 and is used to distribute the local oscillation signal into N channels, which are then sent to each channel's amplitude- and phase-adjustable transmission front end.

[0042] Each amplitude-phase adjustable transmitting front-end has the same internal structure. Taking the first amplitude-phase adjustable transmitting front-end 133 as an example, it includes a digitally controlled attenuator 1331, a digitally controlled phase shifter 1332, and a power amplifier 1333 connected in series. The input terminal of the digitally controlled attenuator 1331 is connected to one output of the power divider 132 and receives an amplitude control word A1 from the data processing and control unit 12, used to adjust the amplitude of the transmitted signal according to the amplitude control word A1. The digitally controlled phase shifter 1332 is connected to the digitally controlled attenuator 1331 and receives a phase control word P1 from the data processing and control unit 12, used to adjust the phase of the signal according to the phase control word P1. The power amplifier 1333 is connected to the digitally controlled phase shifter 1332 and used to amplify the power of the amplitude-phase adjusted signal. The output terminal of the power amplifier 1333 is connected to the transmitting element 141 in the transmitting antenna array 14, used to send the amplified microwave signal to the transmitting element 141 for radiation into space.

[0043] Similarly, the second amplitude-phase adjustable transmitter front-end 134 includes a digitally controlled attenuator 1341, a digitally controlled phase shifter 1342, and a power amplifier 1343, which respectively receive the amplitude control word A2 and the phase control word P2, and the output is connected to the transmitter element 142. The third amplitude-phase adjustable transmitter front-end 135 includes a digitally controlled attenuator 1351, a digitally controlled phase shifter 1352, and a power amplifier 1353, which respectively receive the amplitude control word A3 and the phase control word P3, and the output is connected to the transmitter element 143. Each amplitude-phase adjustable transmitter front-end has the same structure, and each independently adjusts the amplitude and phase of the transmitted signal according to the corresponding amplitude and phase control word.

[0044] During operation, the microwave signal generated by the transmitting local oscillator 131 is divided into N channels by the power divider 132 and sent to each of the amplitude- and phase-adjustable transmitting front-ends 133, 134, 135... respectively. Each digitally controlled attenuator performs amplitude weighting on the signal according to the corresponding amplitude control words A1, A2, A3... and each digitally controlled phase shifter performs phase compensation on the signal according to the corresponding phase control words P1, P2, P3... After amplitude and phase modulation, each signal is amplified to the required power level by the corresponding power amplifier and sent to the transmitting array elements 141, 142, 143... to radiate into space. Through the coordinated action of the amplitude and phase control words, the transmitted beam forms a directional backtracking in the direction of the microwave power receiving end 2, realizing the directional transmission of microwave power.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A cross-frequency directional backtracking microwave power transmission system based on code division multiplexing reception, characterized in that, The system includes a phased array microwave power transmitter and a microwave power receiver; the phased array microwave power transmitter includes a receiving antenna array, a guidance beacon receiving and processing array, a data processing and control unit, a microwave power transmission channel array, and a transmitting antenna array. The receiving antenna array is electrically connected to the guiding beacon receiving and processing array. The pseudo-code output terminal of the data processing and control unit is electrically connected to the guiding beacon receiving and processing array and synchronously outputs the pseudo-code sequence. The guiding beacon receiving and processing array is electrically connected to the data processing and control unit. The data processing and control unit is electrically connected to the microwave power transmitting channel array. The microwave power transmitting channel array is electrically connected to the transmitting antenna array. The microwave power receiving end includes a guidance beacon generation circuit, a transmitting antenna, a receiving antenna, and a microwave rectifier circuit; the guidance beacon generation circuit is electrically connected to the transmitting antenna, and the receiving antenna is electrically connected to the microwave rectifier circuit. The receiving antenna array consists of multiple sets of receiving array elements arranged in a preset geometry, and is used to receive microwave signals from guiding beacons in space. The guidance beacon receiving and processing array is electrically connected to the receiving antenna array, and performs pseudocode modulation, power synthesis, down-conversion and analog-to-digital conversion on the multiple guidance signals, and outputs the reference branch digital intermediate frequency signal and the composite branch digital intermediate frequency signal. The data processing and control unit receives two digital intermediate frequency signals, and after orthogonal digital downconversion, complex correlation despreading, and phase difference detection, generates amplitude control words and phase control words for each transmission channel. The microwave power transmission channel array completes signal amplitude modulation, phase modulation, and power amplification based on amplitude control words and phase control words; The transmitting antenna array radiates the modulated microwave power signal into space. The microwave power receiver generates an uplink guidance beacon signal through a guidance beacon generation circuit and radiates it through a transmitting antenna. The receiving antenna captures the downlink power microwave signal and converts it into DC output through a microwave rectifier circuit.

2. The inter-frequency directional backtracking microwave power transmission system based on code division multiplexing reception according to claim 1, characterized in that, The guidance beacon receiving and processing array includes an N-channel parallel pseudocode modulation radio frequency front-end, a power combiner, a receiving local oscillator, a reference downconversion branch, and a composite downconversion branch. Each pseudocode modulation RF front end consists of a bandpass filter, a low-noise amplifier, and a phase-shift keying modulator connected in series. The bandpass filter removes out-of-band interference, the low-noise amplifier amplifies the weak guide signal, and the phase-shift keying modulator loads a unique pseudocode to give each signal a code division identifier. The first pseudocode modulation RF front-end is used as a reference channel, and the second to Nth channels are used as composite channels; The power combiner combines the modulated RF signals from the second to the Nth channel into a single composite RF signal.

3. The inter-frequency directional backtracking microwave power transmission system based on code division multiplexing reception according to claim 2, characterized in that, The reference downconversion branch of the guidance beacon receiving and processing array includes a mixer, an intermediate frequency filter, an intermediate frequency amplifier, and an analog-to-digital converter connected in series. The composite downconversion branch has the same circuit structure as the reference downconversion branch. The local oscillator receives local oscillator signals and provides them to the reference downconverter branch and the composite downconverter branch, respectively. The intermediate frequency conversion is completed by mixing, and after filtering and analog-to-digital conversion, the digital intermediate frequency signal is output to the data processing and control unit.

4. The inter-frequency directional backtracking microwave power transmission system based on code division multiplexing reception according to claim 3, characterized in that, The data processing and control unit includes a pseudocode generator, two orthogonal digital downconverters, a complex correlation despreader, a phase difference detector, and an amplitude-phase control word generator; The pseudocode generator synchronously outputs pseudocode sequences to each phase shift keying modulator and complex correlation despreader; Two orthogonal digital downconverters process the reference and composite digital intermediate frequencies respectively, and output the reference complex baseband signal and the composite complex baseband signal. The complex correlation despreader combines local pseudocode to complete the despreading operation, and the phase difference detector extracts the relative phase difference of each array element; The amplitude and phase control word generator generates amplitude control words and phase control words based on the phase difference and outputs them to the transmit channel array.

5. The inter-frequency directional backtracking microwave power transmission system based on code division multiplexing reception according to claim 4, characterized in that, The microwave power transmission channel array includes a local oscillator, a power divider, and an N-channel parallel amplitude-phase adjustable transmission front-end; The local oscillator generates a microwave local oscillator signal, which is then evenly distributed to each transmitting front-end via a power divider. Each amplitude- and phase-adjustable transmitter front end is sequentially equipped with a digitally controlled attenuator, a digitally controlled phase shifter, and a power amplifier; The numerically controlled attenuator receives the amplitude control word to achieve amplitude regulation, the numerically controlled phase shifter receives the phase control word to achieve phase conjugate compensation, and the power amplifier completes power amplification before being connected to the corresponding transmitting array element.

6. The inter-frequency directional backtracking microwave power transmission system based on code division multiplexing reception according to claim 5, characterized in that, This system introduces a frequency scaling factor through the digital domain. k=f 2 / f 1. Implement phase mapping under different frequency conditions to ensure consistency of direction backtracking angle.

7. The inter-frequency directional backtracking microwave power transmission system based on code division multiplexing reception according to claim 6, characterized in that, The system has dual-mode adaptive capability: for moving targets, the amplitude and phase control word is updated in real time to achieve dynamic beam tracking; for stationary targets, the control word is locked and the receiving link is shut down to reduce system power consumption.

8. The inter-frequency directional backtracking microwave power transmission system based on code division multiplexing reception according to claim 7, characterized in that, The system supports time-division multiplexing of multiple targets. By loading multi-guide beacons with different frequencies, it generates multi-directional power beams in a time-division manner, which is suitable for multi-target power supply scenarios of UAV swarms.

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