US Government As Represented by the Secretary of the Army

DaHan Liao

Gregory James Mazzaro

Kelly D Sherbondy

Calvin Duc Le

Traian V Dogaru

A subsurface interferometric synthetic aperture radar (InSAR) imaging technique for the detection and localization of underground targets in the presence of a rough ground surface comprises a two-step procedure. First, surface clutter suppression is performed with a polarimetric difference operation that does not alter the propagation phase of the target scattered signal; then a subsurface interferometric algorithm is applied to infer target depth by correlating the clutter-suppressed images obtained along two observation paths.

Interferometric synthetic aperture radar imaging of subsurface structures

A Vivaldi antenna having an upper conductor and a lower conductor. A signal connector feed is attached to a rear end of the conductors while each conductor includes a curved flare section extending forwardly for the reception or transmission of the signal. Each conductor includes elliptical loading section or sections disposed around its flare section to enhance performance of the antenna by improving the front to back ratio as well as other factors for the antenna.

Modified antipodal vivaldi antenna with elliptical loading

A radar system for detecting a target containing electronic components. The radar system includes a radiofrequency transmitter which generates a radar signal at a fundamental frequency. A modulator modulates the radar signal at a modulation frequency and the modulated radar signal is coupled to a transmission antenna. A receiver receives an echo from the radar signal. A filter isolates the harmonics of the fundamental frequency from the echo and a demodulator then compares the phase of the harmonics of the echo with the phase of the harmonics of the radar signal and generates an output signal representative thereof. An imaging algorithm receives the output signal and creates a two-dimensional image of the received echo and then displays that image on a display.

Two-dimensional RF harmonic imaging system and algorithm

A radar assembly for linear and nonlinear radar transmission and reception comprising a signal generator; at least one filter operatively connected to the signal generator; a transmitter operatively connected to the at least one filter for transmitting radar signals; a receiver operative to receiving received signals comprising linear and nonlinear responses from the reflected transmitted signals; the receiver comprising a first channel for processing the linear response of the received signal; a second channel for the processing the nonlinear response of the received signal; at least one switch operative to select one of the first or second channels; at least one high pass filter operatively connected to the second channel to attenuate the linear response; at least one amplifier to amplify the nonlinear response; and at least one display operatively connected to both the first and second channels for displaying both linear and nonlinear responses.

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Laurel, MD, United States of America

DaHan Liao