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.

An RFID tag is described with an antenna and a passive reflector. In an example, the RFID tag has a dielectric substrate. A first conductive pattern is on the dielectric substrate to form an antenna. An RFID integrated circuit (IC) chip is on the dielectric substrate having an antenna port electrically coupled to the antenna, the antenna port being configured to provide RF energy from a reader to the RFID IC chip through the antenna, the RFID IC chip being configured to provide a response to the reader through the antenna. A second conductive pattern is on the dielectric substrate beside the antenna in the form of a second dipole to form a passive reflector that is not electrically coupled to the antenna port, the passive reflectors being configured to reflect RF energy from the reader away from the antenna.

A device and method for detecting presence of a wireless communication device having an antenna with intrinsic characteristics includes a transmitter, a receiver, a memory element, and a processing element. The transmitter may send a first signal to the antenna of the wireless communication device. The receiver may receive a second signal from the antenna of the wireless communication device, the second signal being a first portion of the first signal that is reflected by the antenna based on intrinsic characteristics of the antenna. The memory element may store intrinsic characteristic information for the antenna. The processing element may determine presence of the wireless communication device by analyzing the second signal against the intrinsic characteristic information stored in the memory element.

An antenna monitoring module electrically coupled to an antenna, the antenna monitoring module including an embedded element in the antenna, test antenna configured to send and receive radio frequency (RF) test signals to and from the antenna, an input blocking module disposed at an input of the antenna monitoring module to facilitate receipt of a master test signal by the antenna monitoring module, an addressable mixed signal processor that determines an integrity of a connection to the antenna and a performance of the antenna based on measurements associated with the RF test signals and the master test signal.

An antenna monitoring module electrically coupled to an antenna, the antenna monitoring module including an embedded element in the antenna, test antenna configured to send and receive radio frequency (RF) test signals to and from the antenna, an input blocking module disposed at an input of the antenna monitoring module to facilitate receipt of a master test signal by the antenna monitoring module, an addressable mixed signal processor that determines an integrity of a connection to the antenna and a performance of the antenna based on measurements associated with the RF test signals and the master test signal.

A harmonic radar apparatus includes a transmitter configured to transmit a plurality of fundamental frequencies towards a scene. A further aspect of the harmonic radar apparatus includes a receiver configured to receive a reflected signal from the scene, the reflected signal being modulated based on the scene, and a re-radiated signal from a tag, the re-radiated signal being at a harmonic frequency of at least one of the plurality of fundamental frequencies transmitted by the transmitter.

Inferring product activity includes providing a first product having an attached first harmonic tag; directing, at a first area in which the first product is located, a first transmitted signal of a first frequency; and receiving a first return signal of a first return frequency from the first harmonic tag, wherein the first harmonic tag, upon receiving the first transmitted signal, radiates the first return signal, such that the first return frequency is a harmonic of the first frequency. A computer can then infer, based on the first return signal, a first activity in which the first product is being used.

A strain sensor system emits coarse interrogation signals of different frequencies during a coarse scan while an RF resonant sensor and/or an RF interrogator moves relative to the other. The sensor emits responsive RF signals within a frequency range of a frequency of interest of the sensor. The controller identifies the frequency of interest based on receipt of the responsive signals. The interrogator emits fine interrogation signals of different frequencies during a fine scan subsequent to the coarse scan. The fine signals are emitted at frequencies within a frequency band on both sides of the frequency of interest. The sensor emits responsive RF signals and the controller identifies a center frequency of the RF resonant sensor based on receipt of the responsive signals.

Metamaterials are described which can be employed with satellites, e.g., small sats, to increase the observability of such satellites. Any type of suitable metamaterial can be used. In exemplary embodiments fractal-based patterns or structures may be used.

A code reading method and a radar system using a short-range millimeter wave (mmWave) radar are provided. The method includes transmitting a mmWave radar signal to a target object from a radar system and receiving a reflection wave signal reflected on the target object, extracting reflection signal strengths for a plurality of line codes constituting the target object from the reflection wave signal, compensating for the reflection signal strengths considering a difference in antenna gain between the plurality of line codes as per an antenna radiation pattern of the radar system, forming a radar image using the compensated reflection signal strengths, and reading a binary code from the radar image.