Patent ID: 7535409

Claim:
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.