Abstract: A device detects metallic and non-metallic objects on, flush with, or covered by the ground or other surfaces, or by interfering or obscuring structures or surfaces, using ground penetrating radar, a metal detector and a radiometer. It is specifically designed for detection of non-metallic mines. The coils of the metal detector are mounted in a multi-sensor module with the radar antenna in a co-boresighted and/or co-located arrangement, without degrading the performance of the metal detector or the ground penetrating radar. Preferably, the ground penetrating radar uses a feed and a collimation lens, (such as a Luneberg or Step Dielectric lens), as an antenna to reduce the change in the loss of signal strength due to changes in distance between the surface and the antenna, (for short distances). The collimated beam has approximately constant power for distances closer than twice the diameter of the lens.