Experimental investigation of the acousto-electromagnetic sensor for locating land mines

A hybrid technique is presented that simultaneously uses both electromagnetic and acoustic waves in a synergistic manner to detect buried land mines. The system consists of an electromagnetic radar and an acoustic source. The acoustic source causes both the mine and the surface of the earth to be displaced. The electromagnetic radar is used to detect these displacements and, thus, the mine. To demonstrate the viability of this technique, experimental models have been constructed. The models use an electrodynamic transducer to generate an acoustic surface wave, a tank filled with damp sand to simulate the earth, simulated mines, and a radar to measure the vibrations. The technique looks promising; we have been able to measure the interactions of the acoustic waves with both simulated antipersonnel mines and antitank mines buried in damp sand. We have measured strong resonances in some of the mines; these resonances are shown to help differentiate the mine from clutter.