An identification device that provides identification information is described. This identification device includes a set of radar reflectors that reflect radar signals having a fundamental wavelength. The set of radar reflectors may be arranged in a pattern corresponding to the identification information. For example, the set of radar reflectors may be passive and retrodirective, where a given radar reflector reflects a radar signal back along its prior direction of propagation. Moreover, the pattern may include regions that reflect the radar signals and second regions that do not reflect or scatter the radar signals. During operation, the identification device may receive the radar signals, and then may selectively reflecting the radar signals using the set of radar reflectors to provide the identification information.

The application relates to methods and a driver for communication with a transponder, in particular a driver for installation in a motor vehicle and for communication with a mobile transponder for a vehicle access and/or start system of a motor vehicle, wherein the driver is designed so that, after a first transmission at a first transmission frequency and after driver-side reception of a response of a transponder at the transponder resonance frequency thereof, and after driver-side determination of the response frequency of the response using a frequency detection apparatus,
said response frequency is set, in particular by changing transmission pauses, at the driver as the second transmission frequency, corresponding to the measured transponder resonance frequency, at which the driver is then intended to transmit, wherein the driver has a resonant circuit (2, 3, 4), which has a higher driver resonant frequency than the mentioned first transmission frequency and than the mentioned second transmission frequency of the driver.

A tag measurement environment evaluation device includes a processor and a memory storing a program. The program is configured to, when executed by the processor, cause the processor to determine a moving tag evaluation value of each of a plurality of wireless tags based on a radio wave transmitted from each of the wireless tags and received by a tag reader configured to communicate with each of the wireless tags, and determine whether a measurement environment is suitable for a moving tag detection based on the moving tag evaluation values.

A product locating system is provided. The system includes at least one Radio Frequency (RF) backscatter transmitter configured to emit a main carrier RF signal that forms an excitation signal. The system further includes a passive RF backscatter tag associated with a product and configured to generate an Ultra-Wideband (UWB) signal from the excitation signal. The system also includes at least one RF backscatter receiver configured to simultaneously receive both the excitation signal from the at least one RF backscatter transmitter and the UWB signal from the passive RF backscatter tag, and compute the time-difference-of-arrival (TDoA) therebetween. TDoA information from multiple RF backscatter receivers, including the at least one RF backscatter receiver, is aggregated to compute the location of the product to which the passive RF backscatter tag is attached.

A system for using thin and energy-autonomous backscatter tags and corresponding sensing nodes may operate with 24 GHz backscatter reflectarray tags having low power consumption. A digital beam steering, frequency-modulated continuous wave (FMCW) radar may be used for detection, localization, identification and communications. The tags may include environmental sensors that are used to modulate backscatter waves for data communications directed to a reader or may digitally modulate the backscatter transmissions without sensor data for independent localization of each tag in a network.

A transceiver may wirelessly transmit a communication signal at a first frequency and a sensing signal at a second frequency. The communication signal may include a command that causes a backscatter node to modulate impedance of an antenna, and thereby modulate reflectivity of the backscatter node. The communication signal may also deliver wireless power to the backscatter node. While the impedance is being modulated in response to the command, the transceiver may transmit the sensing signal and measure wireless reflections. The power of the sensing signal may be much lower than that of the communication signal. The transceiver may frequency hop the sensing signal in a wide band of frequencies and take measurements at each frequency in the hopping. Based on the measurements, a computer may determine time-of-flight or phase of a reflected signal from the backscatter node and may estimate location of the backscatter node with sub-centimeter precision.

In some embodiments, a transmitter has a first mode and a second mode. The transmitter is configured to repeatedly send discrete first wireless signals carrying transmitter identification information uniquely associated with the transmitter in the first mode and to send a second wireless signal carrying the transmitter identification information in the second mode. A receiver is configured to receive a wireless signal of the first wireless signals such that the receiver is activated by the wireless signal of the first wireless signal and, in response to receiving the wireless signal of the first wireless signals, to send a third wireless signal carrying the transmitter identification information to the transmitter. The transmitter is configured to transition from the first mode to the second mode in response to receiving the third wireless signal and determining that the third wireless signal includes the transmitter identification information uniquely associated with the transmitter.

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.

In an Electronic Article Surveillance (EAS), a radio frequency identification (RFID) subsystem of an EAS system, can detect a presence of an RFID tag in an RFID interrogation zone associated with a boundary of a controlled area. The EAS system can first determine that the RFID tag is not authorized to leave the controlled area across the boundary. A radar subsystem of the EAS system can second determine, within a first window of time around the first detecting, whether an object in motion is associated with the boundary. The EAS system can alarm based upon both determining that the RFID tag is not authorized to leave the controlled area and determining that the object in motion is associated with the boundary.

A system for determining the position of a transport vehicle that can be moved over a floor, in particular a heavy-load transport vehicle, comprising an antenna which can be attached to a lower face of the transport vehicle and a transponder which can be introduced into the floor at a specific location and which can be charged by means of a transmission field that can be generated by the antenna during a transmission interval and can be evaluated during a subsequent evaluation interval. The system is designed such that the evaluation interval is discontinued and a new transmission interval is started if a signal of the transponder cannot be detected during a detection interval within the evaluation interval.