Abstract: A transmission apparatus for a wireless device, comprising: an antenna for receiving an original signal and for backscattering a modulated signal containing information from the wireless device; a variable impedance coupled to the antenna, the variable impedance having an impedance value; and, a decoder coupled to the variable impedance for modulating the impedance value, and thereby a backscattering coefficient for the antenna, in accordance with the information to generate the modulated signal.

Abstract: A transmission apparatus for a wireless device, comprising: an antenna for receiving an original signal and for backscattering a modulated signal containing information from the wireless device; a variable impedance coupled to the antenna, the variable impedance having an impedance value; a delta-sigma modulator coupled to the variable impedance for modulating the impedance value, and thereby a backscattering coefficient for the antenna, in accordance with the information to generate the modulated signal; and, a decoder coupled to the delta-sigma modulator for generating the impedance value from the information.

Abstract: An inductive coupling apparatus for modifying an incoming radio frequency (RF) signal includes an inductive element for modifying the incoming RF signal in accordance with a coupled impedance characteristic of the inductive element. A variable impedance circuit includes an output electrically coupled to the inductive element. A low pass delta sigma modulator is coupled to the variable impedance circuit and digitally controls the output of the variable impedance circuit, the coupled impedance of the inductive element being adjusted based on the output of the variable impedance circuit.

Abstract: An inductive coupling apparatus for modifying an incoming radio frequency (RF) signal includes an inductive element. A variable impedance circuit includes an output electrically coupled to the inductive element. A band-pass delta sigma modulator is coupled to the variable impedance circuit and digitally controls the output of the variable impedance circuit. The incoming RF signal is modified as the coupled impedance of the inductive element is adjusted in accordance with the output of the variable impedance circuit.

Abstract: A method for locating wireless devices within a local region, comprising: determining respective global locations of two or more of the wireless devices; determining whether the wireless devices are within the local region by calculating respective distances between the global locations; determining respective ranges between the wireless devices within the local region; and, determining respective relative locations of the wireless devices within the local region by triangulation using the ranges.

Abstract: A method for identifying and ranging a wireless device, comprising: transmitting an original radar signal from a detecting system; in response to the original radar signal, receiving a modulated radar signal at the detecting system, the modulated radar signal being backscattered from an antenna of the wireless device and containing information pertaining to the wireless device, and the modulated radar signal being a frequency offset version of the original radar signal; and, using a processor at the detecting system, determining an identity and a range of the wireless device from the modulated radar signal.

Abstract: An antenna apparatus for backscattering an incoming radio frequency (RF) signal includes an antenna for backscattering the incoming RF signal in accordance with a reflection coefficient characteristic of the antenna. A variable impedance circuit includes an output electrically connected to the antenna. A band-pass delta sigma modulator is coupled to the variable impedance circuit and digitally controls the output of the variable impedance circuit, such that the reflection coefficient of the antenna is adjusted based on the digitally controlled output of the variable impedance circuit. In an RFID network, the apparatus and method reduces the effect of DC offset in the reader device and the effects of the reader device's phase noise, while allowing for complex modulations.

Abstract: An antenna apparatus for backscattering an incoming radio frequency (RF) signal includes an antenna for backscattering the incoming RF signal in accordance with a reflection coefficient characteristic of the antenna. A variable impedance circuit includes an output electrically connected to the antenna. A low pass delta sigma modulator is coupled to the variable impedance circuit and digitally controls the output of the variable impedance circuit, such that the reflection coefficient of the antenna is adjusted based on the output of the variable impedance circuit.