Advanced imaging for down-looking contactless GPR systems

This paper investigates the performance of an advanced imaging procedure for ground penetrating radar (GPR) operating in contactless configuration, i.e., when data are collected at variable distances from the air-soil interface. A data processing procedure is presented, based on an advanced implementation of a microwave tomographic approach. This improved version, recently proposed by the authors, is able of accounting for the near-field distribution generated by a directional transmitting antenna. The effectiveness of the procedure is shown by processing numerical data, which are obtained by suitably implementing a realistic system on a full-wave commercial simulator. Metallic canonical objects are considered to compare the reconstruction capabilities of the proposed algorithm with respect to more conventional procedures, as well as to assess the role of the antenna distance from the air-soil interface.