Improvement of Resolution for GPR by the Contributions of Evanescent Waves

摘要

The ability to detect buried objects in the ground is influenced by the presence of the air ground interface. In the far field the capability to resolve objects in lateral direction with a synthetic aperture system is limited by the angle of total reflection. If the air gap between antenna and ground is small, the system resolution can profit by evanescent parts of the plane wave spectrum which decay exponentially for directions beyond the angle of total reflection. Another important factor which has influence on spatial resolution is the used type of antenna. In the paper the resolution limits will be discussed as well as the potential benefits by evanescent modes followed by an experimental verification.