When a georadar is working in a tunnel, reflections from metallic mechanisms may be a serious interference. Therefore it is important to enlarge “front to back” ratio of antennas. A spacing between the antenna and the ground surface, which may be due to roughness of the surface, usually diminishes the front to back ratio. A placing of deformable resistive material into the spacing, as proposed by A.G.Chernokalov, increases the front to back ratio.