Cross-Well Radar. II: Comparison and Experimental Validation of Modeling Channel Transfer Function

Abstract

Close agreement between theory and experiment is critical for adequate understanding and implementation of the cross-well radar (otherwise known as cross-borehole ground penetrating radar) technique, mentioned in a previous paper by the authors. Comparison of experimental results to simulation using a half-space dyadic Green’s function in the frequency domain requires development of transfer functions to transform the experimental data into a compatible form. A channel transfer function (CTF) was developed to avoid having to model the transmitting and receiving characteristics of the antennas. The CTF considers electromagnetic wave propagation through the intervening media only (soil in this case) and hence corresponds to the simulation results that assume ideal sources and receivers. The CTF is based on assuming the transmitting antenna, soil, and receiving antenna as a cascade of three two-port microwave junctions between the input and output ports of the vector network analyzer used in the experimental measurements. Experimentally determined CTF results are then compared with computational model simulations for cases of relatively dry and saturated sandy soil backgrounds. The results demonstrate a reasonable agreement, supporting both the model and CTF formulation.