4437results about "Resonant long antennas" patented technology

A radio frequency (RF) transmit / receive switch. The transmit / receive switch comprises an impedance matching circuit and a voltage scaling circuit. The impedance matching circuit matches an incoming RF signal to a low noise amplifier and an outgoing RF signal from a power amplifier. The voltage scaling circuit, coupled to the impedance matching circuit, the power amplifier, and the low noise amplifier, attenuates the outgoing RF signal to a scaled signal within a breakdown voltage of a transistor device in the low noise amplifier during transmission of the outgoing RF signal.

A radio frequency power amplifier includes a feedback control system coupled to an input signal and a first feedback signal and configured to provide an output; a controlled supply configured to provide power that is controlled in accordance with a signal; and a radio frequency gain stage powered from the controlled supply, driven by the output from the feedback control system, and configured to provide an output signal at the radio frequency to a resonant load, where the first feedback signal corresponds to the output signal. Some embodiments include a sequencer in the feedback control system and others utilize an additional feedback loop to control the power provided by the controlled supply.

A network for power transmission to a receiver that converts the power into current includes a first node for transmitting power wirelessly in a first area. The first area has a minimum electric or magnetic field strength. The network includes a second node for transmitting power wirelessly in a second area. The second area has a minimum electric or magnetic field strength and overlaps the first area to define an overlap area. In another embodiment, the network includes a source in communication with the first and second nodes which provides power to them. Also disclosed are methods for power transmission to a receiver that converts the power into current.

An intelligent antenna system for extending the effective communication range of a machine-readable passive tag. The system includes intelligence that allows one of a plurality of extension antennas to be active at any given time in order to both facilitate communications and safeguard the system. The machine-readable tag and antenna system may be embedded in a structure. In a further embodiment, the system may include multiple passive tags that are active in correspondence to a display or advertisement currently being exhibited. The system includes means for operatively coupling a designated machine-readable tag to the embedded antenna network previously described. In a further embodiment of the invention, the machine-readable tag includes combined RFID and NFC functionality where both RFID listening functions and NFC read-write functions are to be available in the same NFC communications logic, where different RFID listening applications require different minimum separation distances between the reader and the NFC communications logic. The NFC communications logic chip is selectively connected to at least three antenna coils, the first antenna coil for operating with a first minimum separation distance between the reader and the NFC communications logic, the second antenna coil for operating with a second minimum separation distance between the reader and the NFC communications logic, and the third antenna coil for reading and writing. In a further embodiment of the invention, matching circuits are included with the respective antenna coils to tune the resonant frequency of the RLC oscillator circuit for each antenna coil in the NFC communications logic.