The results of several helicopter-borne short pulse radar surveys over frozen and thawed freshwater bodies are discussed. The examples given are geologically simple so that effects of the system could be separated from the complications of wave propagation in the ground. As expected best performance was achieved using well isolated and small high-frequency antennas at slow speeds and low altitudes over smooth interfaces defining low loss media. In addition the isolation of the airborne antenna from ground loading permits application of deconvolution filtering based on the known, constant radiated pulse waveform. The major obstacles to deeper earth penetration using high power, low frequency transmitters and antennas are high surface reflectivity and aircraft clutter. Current research is looking at methods to suppress these unwanted effects.
Samenvatting