Recognition of Borehole Radar Cable-Related Effects Using Variable Offset Sounding

Conductive cables can influence borehole radar measurements and introduce artifacts into data and therefore must be considered during data analysis and interpretation. This study presents examples of some cable-related effects in data acquired with a radar system that relies on conductive cables for signal transmission. Data show that measurements can be affected when energy radiated from the transmitter antenna induces currents on conductive cables, which can function as an electromagnetic waveguide, allowing fields to propagate along cables and be detected by the receiver antenna. Additionally, periodic artifacts can result when currents traveling on cables reflect at system impedance mismatches.Variable offset soundings (VOS) are not typically conducted during borehole radar studies, but can be useful for recognizing cable-related effects on recorded data and studying propagation characteristics in a borehole. In addition to single-hole VOS measurements, VOS measurements made on the ground surface using E-Plane and H-Plane configurations are shown to have the potential for providing additional insight in regards to coupling mechanisms between borehole antennas and cables.