UC Davis

We develop the theory behind and a prototype of a 0.3-12 GHz ground-penetrating radar (GPR) system foruse in imaging the subsurface environment. Experimental results show that the prototype GPR system is likely able to perform in field applications including buried utility detection and humanitarian demining operations. First, we present two antenna designs – the resistively loaded vee dipole (RLVD) and elliptical RLVD based on a Guanella balun structure. However, we found a disconnect between the performance of these antennas in simulation and the real-world system performance. Therefore, we have developed a theory of how the less-often-considered aspects of antennas including coupling, distortion, beamwidth, and radar cross section dramatically affect the overall imaging performance. We perform a deep-dive into the causes, solutions, and design decisions that each aspect of the antenna requires in order to make it more likely that an antenna will perform well in the niche application of GPR. In order to validate and apply these principles in the real world, we present the creation of a 0.3-12 GHz GPR system in both the lab and outside environments. We show the entire build of the custom FPGA-based sampling receiver, examine the VHDL backend for data offloading, and describe the real-time visualization system. Next, we show in depth the signal-processing pipeline required to take raw data to a pre-processed image: de-glitching, de-jittering, and background removal algorithms, among others. The Kirchhoff-Migration imaging algorithms used to transform the pre-processed data into human-readable images are presented in detail. Finally, lab-based and real-world underground imaging results are presented as validation of the operation of the GPR system. We demonstrate the detection of steel rebar in a laboratory sandbox imaging test and portions of the underground structure around Kemper Hall at UC Davis.