FMCW Subsurface Microwave Imaging with Hexagonal Antenna Arrays

Abstract

Ground-penetrating radar (GPR) imaging is typically conducted in the pulse-echo mono-static format with a simple CW pulse as the probing signal. Recently, the data-acquisition hardware has been extended to the use of linear multi-element arrays. This paper presents an advanced GPR imaging system with FMCW probing waveforms, with a seven-element hexagonal array and software-defined data-acquisition hardware. The use of FMCW probing signals is for the optimization of the information contents of the returned waveforms. The utilization of the hexagonal unit is to produce sub-images with direction-independent resolution capability. In this paper, mathematical analysis, system modeling, field experiments, and image reconstruction are included to illustrate the performance and capability of the engineering concepts.