The Army Research Laboratory (ARL) synchronous impulse reconstruction (SIRE) forward-looking radar

The Army Research Laboratory (ARL) has designed and fabricated a forward-looking, impulse-based, ultra-wideband (UWB) imaging radar for detection of concealed targets. This system employs a physical array of 16 receive antennas to provide the necessary aperture for sufficient cross-range resolution in the forward-looking geometry. Each antenna feeds a base-band receiver/digitizer that integrates the data from a number of radar pulses before passing it on to the personal computer (PC) based operator's console and display. The innovative ARL receiver design uses commercially available integrated circuits to provide a low-cost, lightweight digitizing scheme with an effective sampling rate of approximately 8 GHz. The design is extensible to allow for growth in the number of channels used and improvements in integrated circuit performance to eventually meet the expected unmanned ground vehicle combat pace. Down-range resolution is provided by the bandwidth of the transmitted pulse which occupies 300-3000 MHz. Range coverage is designed to be 25 meters with an adjustable start point forward of the vehicle. Modeling studies have shown that a pair of transmitters situated at the two ends of the receive array provides best performance in cross-range resolution. Radar data is continuously collected so that a horizontal two-dimensional synthetic aperture is formed for 3-D image formation. This allows focusing of the data to yield estimates of target height as well as position to tag potential obstacles as being negative (e.g. holes, ditches) or positive (e.g. tree stumps). The forward motion also improves the cross range resolution to targets as their aspect changes.