A transceiver assembly is configured to detect an object. The transceiver assembly includes a first transmit antenna array configured to transmit a first signal at a first frequency, a second transmit antenna array configured to transmit a second signal at a second frequency that differs from the first frequency, and a receive antenna array configured to receive a third signal at a third frequency that is a difference between the first frequency and the second frequency. The transceiver assembly detects the object in response to reception of the third signal by the receive antenna array.

Examples of imaging systems are described herein which may implement microwave or millimeter wave imaging systems. Examples described may implement partitioned inverse techniques which may construct and invert a measurement matrix to be used to provide multiple estimates of reflectivity values associated with a scene. The processing may be partitioned in accordance with a relative position of the antenna system and/or a particular beamwidth of an antenna. Examples described herein may perform an enhanced resolution mode of imaging which may steer beams at multiple angles for each measurement position.

The present disclosure is directed to a measurement system for measuring a reflection coefficient of a test sample, including: a transceiver antenna configured to be coupled to a source of electromagnetic radiation; and a RAM positioned between the transceiver antenna and a measurement region of the transceiver antenna, wherein the RAM comprises an aperture substantially orthogonal to and substantially aligned with a transceiving axis of the transceiver antenna. A method for obtaining error correction of a measurement system and a method of measuring a reflection coefficient in a test sample are also provided.

Trapped or confined individuals may be located and rescued by detecting their vital signs (e.g., chest movement or heart beat) using reflected, radio frequency signals over a range of multiple antenna polarities.

A microwave imaging system is provided. The microwave imaging system comprises at least one transmitter circuit and a plurality of receiver circuits. The microwave imaging system further comprises at least one direct digital synthesizer (DDS) circuit, for generating a signal that is provided as an input to each of the plurality of receiver circuits by the at least one transmitter. The microwave imaging system further comprises a clock generation module which is configured to provide a clock signal to each of the at least one transmitter circuit, the plurality of receiver circuits, and the DDS circuit.

A method comprises scanning a subject with a coherent radar beam from a single chip operating in the terahertz range, and executing instructions, on a processor, to create one or more digital images based said scanning. One or more digital images are combined at the processor to form a super image, and based on the super image, the processor determines whether the subject is carrying a concealed object. if the subject is determined to be carrying a concealed object, and certain alert-generating rules are met, an alert is generated.

A millimeter-wave three-dimensional holographic imaging method and system. The method comprises: transmitting a continuous frequency wave to a measured human body, and receiving an echo signal reflected back; performing Fourier transform, phase compensation, inverse Fourier transform, and “non-uniform sampling to uniform sampling” interpolation; and projecting three-dimensional echo data to obtain two-dimensional reconstruction data, and generating a two-dimensional reconstructed image.

A method for operating a stepped frequency radar system is disclosed. The method involves performing stepped frequency scanning across a frequency range using frequency steps of a step size, the stepped frequency scanning performed using at least one transmit antenna and a two-dimensional array of receive antennas, changing at least one of the step size and the frequency range, and performing stepped frequency scanning using the at least one transmit antenna and the two-dimensional array of receive antennas and using the changed at least one of the step size and the frequency range.

A system for detecting a threat at a facility, such as a weapon, and automatically implementing security procedures including opening and/or closing doors of the facility to isolate the threat from facility occupants. Additionally or alternatively, one or more egress routes may be established by opening and/or closing certain doors to aid facility occupants in evacuating the facility while avoiding the threat.

A terahertz security inspection robot is provided, including: a housing including a main housing and a head housing rotatably connected to the main housing; a terahertz wave imaging mechanism including a mirror assembly arranged in the head housing and a detector array arranged in the main housing; and a rotating mechanism configured to cause the head housing and the mirror assembly located in the head housing to rotate with respect to the main housing, so that the mirror assembly of the terahertz wave imaging mechanism is oriented in different directions to respectively perform terahertz scanning and imaging on objects to be inspected in different inspection regions in a security inspection scene.