Research progress on the design, construction, and operation of a novel, airborne ground penetrating radar system to detect surface and subsurface landmines is presented. The landmine detection system is unique in that active, electronic projectiles are shot into the ground from an airborne platform to create high power, monopulse radar signals. Intimate contact between the projectile and the ground reduces the amount of reflected radar energy at the air-soil interface and ensures that maximum radar energy is propagated into the surrounding ground. The end result is that the reflected radar signal is of higher energy and possesses a higher signal-to- noise ratio allowing enhanced detectability. The high power, monopulse signal that is reflected off the landmine is received at the airborne platform via scanned antenna array. In comparison, conventional ground penetrating radar systems typically use chirped or long pulse signals and horn type antennas located close to the ground limiting their usefulness in this application. To generate electrical energy, two types of projectiles are used and are based on the principle of magnetic flux compression or by the principle of piezoelectric compression. The performance results of these two projectile types as well as the models used to predict their behavior are presented and discussed. To evaluate the overall performance of the system, a sub-scale radar test range was also constructed. The radar test range consists of a large dirt- filled tank containing a high power impulse source, several targets that simulate buried landmines, and a post scanned antenna array located above the dirt-filled tank. The high power impulse source simulates the radar signal generated when the projectiles impact the ground. The radar cross-sectional data generated in the test range is presented and discussed.
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