A frequency modulated continuous wave radar system includes at least one identity tag, respectively disposed next to at least one test subject; and a frequency modulated continuous wave radar identity recognition device, including an identity recognition control module, for controlling a test identity tag of the at least one identity tag to be turned on to generate a specific tag reflection signal corresponding to an identity frequency in response to a chirp signal; and a frequency modulated continuous wave radar, for transmitting the chirp signal and receiving at least one reflection signal of the at least one test subject and the specific tag reflection signal in response to the chirp signal, to calculate and determine that the specific tag reflection signal and a specific reflection signal of the at least one reflection signal are corresponding to an adjacent position information. The specific reflection signal is corresponding to test subject information.

Systems and methods to determine motion parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, a method implemented in a radio frequency identification (RFID) system includes determining a motion parameter of the RFID tag based on detecting a Doppler frequency shift in a radio frequency signal received from the RFID tag.

A method, system and apparatus are provided for estimating characteristics of a wireless communication channel between at least two passive radio frequency (RF) nodes. Backscatter channel state information (BCSI) is measured during communication between the at least two passive RF nodes using the wireless communication channel. An RF node aggregates the measured BCSI and the aggregated BSCI is analyzed to detect at least one activity of a plurality of activities.

Systems and methods to determine motion parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, a method implemented in a radio frequency identification (RFID) system includes determining a motion parameter of the RFID tag based on detecting a Doppler frequency shift in a radio frequency signal received from the RFID tag.

A device for selectively reflecting an incident microwave signal or millimeter-wave signal includes multiple antennae disposed in an array. Each antenna has an input adapted to selectively receive a forward bias signal or a zero bias signal. The device also includes a diode disposed at each input of each antenna. The device also includes a switching device connected to each input, and configured to selectively apply a forward bias or zero bias to each of the diodes. In forward bias, each of the antennae detects the incident microwave signal or millimeter wave signal, and in zero bias, each of the antennae reflects the incident microwave signal or millimeter wave signal.

Apparatus comprising at least one reflective surface configured to reflect electromagnetic waves, wherein a reflective response of at least one portion of said reflective surface with respect to said electromagnetic waves is electronically controllable, wherein said apparatus is configured to at least temporarily control said reflective response of said at least one portion of said reflective surface.

Markers and related systems and methods are provided for localizing lesions within a patient's body, e.g., within a breast. The marker includes one or more photosensitive diodes for transforming light pulses striking the marker into electrical energy, one or more antennas, and a switch coupled to the photodiodes and antennas such that the light pulses cause the switch to open and close and modulate radar signals reflected by the marker back to a source of the signals. The antenna(s) may include one or more wire elements extending from a housing, one or more antenna elements printed on a substrate, or one or more chip antennas. Optionally, the marker may include a processor coupled to the photodiodes for identifying signals in the light pulses or one or more coatings or filters to allow selective activation of the marker.

A technique for transmitting data from a passive radio device (100) is described. As to a method aspect of the technique, an antenna (102) of the passive radio device (100) is exposed to an incident radio signal (502). A frequency domain representation of the incident radio signal (502) comprised at least one muted gap between active subcarriers within a bandwidth of the incident radio signal (502). The incident radio signal (502) is backscattered from the antenna by modulating an impedance of the antenna according to the data using at least two different modulation frequencies that differ by less than the bandwidth.

The modulation includes in amplifying the microwave signal phase shifted by a given angle into a first sinusoidal signal, in order to obtain a first amplified signal; and in amplifying the microwave signal phase shifted by the given angle increased by into a second sinusoidal signal phase shifted by with respect to the first signal, in order to obtain a second amplified signal phase shifted by with respect to the first amplified signal; the modulated microwave signal being the sum of the first amplified signal and the second amplified signal.

Markers and related systems and methods are provided for localizing lesions within a patient's body, e.g., within a breast. The marker includes one or more photosensitive diodes for transforming light pulses striking the marker into electrical energy, one or more antennas, and a switch coupled to the photodiodes and antennas such that the light pulses cause the switch to open and close and modulate radar signals reflected by the marker back to a source of the signals. The antenna(s) may include one or more wire elements extending from a housing, one or more antenna elements printed on a substrate, or one or more chip antennas. Optionally, the marker may include a processor coupled to the photodiodes for identifying signals in the light pulses or one or more coatings or filters to allow selective activation of the marker.