3D subsurface visualization by suppressing ground reflection and direct wave with bistatic GPR

A ground reflection and a direct wave which propagates directory from a transmitting antenna to a receiving antenna are often arisen as issues especially for a ground penetrating radar (GPR) to monitor a near-surface region. In this paper, a 3D subsurface radar image by suppressing those components with a bistatic GPR system is presented. A relative permittivity of a ground surface is measured at the beginning, and a Brewster angle is estimated from that value. Then, the transmitting antenna is located to match an incident angle with the Brewster angle. In this case, the ground reflection does not occur, and all the energy penetrates into the ground. The direct wave is suppressed with an f-k filter which works automatically from position information of the antennas. An experimental result gives the 3D subsurface image without the ground reflection and the direct wave under a condition that a landmine model is buried at a depth of 10cm in a dry sand.