<title>Humanitarian multisensor hand-held mine detector: design of a GPR array</title>

Abstract

At present the most effective mechanical aids for the post conflict hand clearance of anti-personnel mines are metal detectors and probes. These are effective against the majority of current mine threats but clearance rates are limited because of the high incidence of false targets in post conflict areas. Such false targets must be exposed and removed with the same care required for handling genuine ordnance. Clearance rates would be substantially improved if false targets detected by metal detectors could be distinguished from mine threats and thus left in place. One possible approach to the problem of differentiating between metal fragments and anti-personnel land mines is the use of multiple sensors. In this paper we discuss the design of a GPR for such a multi-sensor detector head. One of the challenges for combined metal detectors and GPR is the design of the GPR antenna so that it can operate effectively in the presence of metal detector coils. For a practicable device the GPR antennas must operate with the metal detector coils in their near field and coupling between sensors is of primary importance. The antennas must also be designed so that their influence on the metal detector's sensitivity is minimized. In this paper we present one solution for this problem and present experimental results showing the how the proposed GPR design operates in the presence of metal detector coils and in the presence of a resistive transducer located below the antenna array. The GPR concerned uses a 3x3 antenna array and post reception synthetic aperture processing to provide a 3d image of the ground underneath the sensor. Focussed images of various targets are presented, and images to demonstrate the effects of the other sensors on the GPR are shown.