302 results about "Rf field" patented technology

An arrangement is provided for charging a charge storage device by placing the charge storage device in an RF or microwave radiation field. One or more antennas which receive the radiated RF electromagnetic field are placed on the charge storage device. Rectifiers connected to the antennas rectify the received RF electromagnetic field an produce a DC output current which is used to charge the charge storage device. The charge storage device may be a battery or a capacitor and may form an integral part of an electronic device. The same RF field that charges the charge storage device can also be employed to communicate data to transponders which may be associated with computing devices.

Decoupling circuits are provided which transfer energy induced from an MRI pulsed RF field to an energy dissipating surface. This is accomplished through broadband filtering or by resonant filtering. In a passive component network for an implantable leadwire of an active implantable medical device, a frequency selective energy diversion circuit is provided for diverting high-frequency energy away from a leadwire electrode to a point or an area spaced from the electrode, for dissipation of high-frequency energy.

An RFID tag is powered both by an internal battery and passively by an interrogating RF field. As a result, the RFID tag can be passively powered after the internal battery has been depleted. More particularly, an embodiment of the RFID tag includes electronic circuitry to provide RFID functionality, and an energy storage device coupled to the electronic circuitry to provide an operational voltage thereto. A battery is operatively coupled to the energy storage device to charge the energy storage device. A rectified RF power source derived from an interrogating RF field is also operatively coupled to the energy storage-device to charge the energy storage device. The rectified RF power source and the battery are electrically separated from each other. The energy storage device remains charged by the battery in the absence of the RF interrogating field while the battery has remaining capacity. After the battery has become depleted, the energy storage device is charged by the presence of the RF interrogating field.

A RF-ID based wireless terminal has shortened session set-up and user identification time for conducting transactions with interactive service applications. The wireless terminal includes a terminal identification number and a user identification as a RF-ID tag. A RF-ID reader transmits a RF field for detecting the RF-ID tag in the terminal and provides an output signal when the terminal is within the reader field. The output signal establishes a connectionless communication to an access point or other terminal which initiates a wireless paging operation, in lieu of conducting a terminal discovery process, based upon the content of the RF-ID tag. The terminal initiates a wireless session between the terminal and the access point or terminal for conducting transactions with a service application linked to the access point or terminal.

The present invention is directed toward secure access systems. Specifically, a radio frequency (RF) enabled device is provided that includes an RF powered human feedback element. An interrogator emitting an RF field may control the human feedback element through the RF field such that information may be transmitted from the interrogator to the device.

An apparatus having a coil of wire, energized by a repetitively pulsed radio frequency (RF) power source to provide electromagnetic fields to a region within a body. A scanning, directional hydrophone acoustically connected to the body, samples ultrasonic radiation generated by the RF fields at the RF frequency or twice the RF frequency induced from conductive spots. Signals from the hydrophone are analyzed with regard to their time of arrival relative to the RF pulses and with respect to their direction of arrival. These collected data are recorded and displayed as images of the spots within the region.

Decoupling circuits are provided which transfer energy induced from an MRI pulsed RF field to an energy dissipating surface. This is accomplished through broadband filtering or by resonant filtering. In a passive component network for an implantable leadwire of an active implantable medical device, a frequency selective energy diversion circuit is provided for diverting high-frequency energy away from a leadwire electrode to a point or an area spaced from the electrode, for dissipation of high-frequency energy.

Ion manipulation systems include ion repulsion by an RF field penetrating through a mesh. Another comprises trapping ions in a symmetric RF field around a mesh. The system uses macroscopic parts, or readily available fine meshes, or miniaturized devices made by MEMS, or flexible PCB methods. One application is ion transfer from gaseous ion sources with focusing at intermediate and elevated gas pressures. Another application is the formation of pulsed ion packets for TOF MS within trap array. Such trapping is preferably accompanied by pulsed switching of RF field and by gas pulses, preferably formed by pulsed vapor desorption. Ion guidance, ion flow manipulation, trapping, preparation of pulsed ion packets, confining ions during fragmentation or exposure to ion to particle reactions and for mass separation are disclosed. Ion chromatography employs an ion passage within a gas flow and through a set of multiple traps with a mass dependent well depth.

A method and apparatus for modulating at least one of energy and current of an electron beam in a linac for fast switching of particle beam energy on a time scale comparable with, and shorter than, the interval between linac pulses. Such modulation may be achieved by dividing, in a coupler, a radio-frequency (RF) field into field components and coherently adding these components in a phase shifting section to selectively direct the RF field to a chosen section of the linac. The phase shifting section may include at least one arm containing at least one fast switch and at least one phase changer. In specific embodiments, the phase shifting section may include an electronically controlled plasma switch and a plasma short.

An RFID device detection system includes a proximity locator, which generates an electric field for reading an antennaless RFID device, or for reading other, antennaed RFID devices. An antennaless RFID device includes non-antenna conductive leads coupled to a chip. The proximity locator includes one or more conductors forming a transmission line structure arranged to set up a strong RF electric field in proximity to the locator. The strong RF electric field may be a short-range field that provides significant RF energy only over a relatively short distance, when compared with traditional RF fields that are set up over a relatively large distance. The short-range RF field allows coupling to antennaed and antennaless RFID devices that are near to the proximity locator. The RFID device detection system may be employed in a variety of tasks, including inventory control and theft detection.

An RF-only multipole includes a spiral resistive path formed around each multipole rod body. RF voltages are applied to the rod body and resistive path, and DC voltages are applied to the resistive path, to create a radially confining RF field and an axial DC field that assists in propelling ions through the multipole interior along the longitudinal axis thereof. In one implementation, the resistive path takes the form of a wire of resistive material, such as nichrome, which is laid down in the groove defined between threads formed on the rod body. The RF-only multipole of the invention avoids the need to use auxiliary rods or similar supplemental structures to generate the axial DC field.

A method and apparatus for detecting RF field strength. A field strength reference generator develops a field strength reference current as a function of a field strength of a received RF signal; and a field strength quantizer develops a digital field-strength value indicative of the field strength reference current. In one embodiment, detected field strength is used to dynamically vary the impedance of a tank circuit whereby, over time, induced current is maximized.

The present invention concerns an apparatus (1′) for NMR spectroscopy and/or NMR imaging of a sample. The apparatus comprises a static probe comprising an outer coil for excitation of nuclei of the sample by generating an incident radio frequency field at the Larmor frequency of the nuclei, and for reception of a return radio frequency field emitted by the sample, and a sensitive inner coil (6a′) which is mounted closely around or in contact with the sample container and which is wirelessly coupled to the outer coil by an electromagnetic radio frequency field. The sensitive inner coil is embedded in an inner spinning rotor (2) which is rotatively mounted inside the static probe and which is integral with the sample container, so that the filling factor and the radio frequency field amplitude in the sensitive coil are maximized.

The present invention discloses a portable magnetic resonance method and device for tissue analysis including a magnetic field generator, a radio frequency source, a radio frequency detector, a power source, and a processor configured for receiving radio frequency signals and for analyzing those signals to determine discriminatory tissue characteristics in a planar section of a region of interest within a patient's body, with the magnetic field generator positioned outside of the patient's body, and more preferably hand held in proximity to the patient's body. The processor is configured to direct the radio frequency source to produce a radio frequency field in varying planar sections of the region of interest at Larmor frequencies such that spins resonant with the Larmor frequency in the particular planar section of the region of interest are excited. The processor is further configured to direct the radio frequency detector to receive magnetic resonance signals produced in each planar section of the region of interest in response to the applied radio frequency field, to compute from the acquired magnetic resonance signals a quantitative metric indicative of discriminatory characteristics of differing tissues or other materials within each such planar section, and to produce human discernable output indicative of such quantitative metric.

In a wireless network comprising access points deployed within a designated zone of coverage, the radio frequency field strength resulting from radiation from the access points is optimised as a function of location by means of control of the transmission power and/or radiation pattern of the access points in response to measurements from sensors at defined locations that measure received signal power, the received power being related to radio frequency field strength. Sensors may be deployed within the designated zone of coverage, at the edge of the zone and/or outside the zone and optimisation of the transmission parameters of the access points in terms of transmission power and/or radiation pattern is carried out taking into account the location of the sensors in addition to the received power at the sensors.