Imaging radar method and system
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsJoon Y Choe, Eung Gi Paek
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Abstract
A time-reversal imaging radar system for acquiring an image of a remote target includes an antenna array having a plurality of spaced-apart antennas, and a transceiver coupled to the antenna array for alternately transmitting a radar signal via the antenna array toward the target and for receiving target-reflected radar signals. The transceiver includes means for multiple-pass time-reversing the transmitted and received radar signals whereby coherent beam focusing is realized at both the target and at the receiver to thereby enhance the resolution of the acquired target image.
Claims13
A method of acquiring a high resolution radar image of a target beyond a diffraction limit in a multipath environment by coherently summing a scattered beam from multiple scatterers along a beam path in order to form a multipath-enabled extended virtual aperture, comprising:
- a) transmitting a first collimated coherent radar signal through a beamformer toward the target to reflect off the target as a first reflected radar signal then subject to distortion and multiple reflections by intermediate scattering sources;
- b) receiving the first reflected radar signal;
- c) processing the first reflected radar signal to generate a time-reversed synchronous and coherent radar signal;
- d) transmitting the time-reversed radar signal toward the target whereby coherent beam focusing with the first radar signal is realized at the target, with the time-reversed radar signal reflecting from the target as a second reflected radar signal time-reversed with the first radar signal;
- e) receiving the second reflected radar signal through the beamformer whereby coherent beam focusing with the first radar signal is automatically realized at the receiver thereby achieving a conjugate imaging between a common target and radar imaging plane;
- f) applying extended virtual aperture by coherently combining the beam scattered by multiple scattering sources to obtain a higher resolution beam focusing;
- and
- g) repeating steps a)-f) for a desired number of steering angles to thereby acquire a high resolution radar image.
A time-reversal radar imaging system for acquiring an image of a remote target, comprising:
- an antenna array including a plurality of spaced-apart antennas and a beamformer;
- a transceiver coupled to the antenna array for alternately transmitting a collimated coherent radar signal via the antenna array through the beamformer toward the target and for receiving target-reflected radar signals;
- and
- wherein said transceiver includes means for multiple-pass time-reversing the transmitted and received radar signals and for applying extended virtual aperture by coherently combining the beam scattered by multiple scattering sources to obtain a higher resolution beam focusing whereby coherent beam focusing is realized at both the target and at the receiver to thereby enhance the resolution of the acquired target image.
A time-reversal radar imaging system for acquiring an image of a remote target, comprising:
- an antenna array including a plurality of spaced-apart antennas;
- a switch;
- a computer programmed to time reverse a first return radar signal prior to retransmitting a time-reversed radar signal toward a target, said computer including a digital clock for signal timing control and synchronization;
- a transceiver coupled to the antenna array through the switch for alternately transmitting a radar signal via a transmitter circuit to the antenna array toward the target and for receiving a reflected radar return signal via a receiver circuit from the antenna array, wherein:
- the transmitter circuit includes a digital beam former;
- the receiver circuit includes:
- a low noise amplifier coupled to the switch;
- an analog-digital converter (ADC) coupled to the low noise amplifier;
- a first fast memory having an input coupled to the ADC, an output coupled to the digital beam former;
- and
- an input/output coupled to the computer;
- and
- the transmitter circuit includes:
- a high power amplifier (HPA) coupled to the switch;
- a digital-to-analog converter (DAC) coupled to the HPA;
- and a second fast memory having a first input coupled to the digital beam former, a second input coupled to the computer, and an output coupled to the DAC;
- and wherein the digital beamformer includes means for applying extended virtual aperture by coherently combining the beam scattered by multiple scattering sources to obtain a higher resolution beam focusing whereby coherent beam focusing is realized at both the target and at the receiver to thereby enhance the resolution of the acquired target image.
Dependencies are inferred from the claim text.