Effect of antenna-surface distance on the radiation of a GPR antenna

TLDR: In this paper, the influence of the proximity of a dielectric interface on the radiation of a GPR antenna was analyzed using an experimental setup consisting of two 1.5 GHz resistively loaded transmit-receive antenna pairs.

Abstract: An experimental investigation was performed to analyze the influence of the proximity of a dielectric interface on the radiation of a GPR antenna. The experimental setup consisted of two 1.5 GHz resistively loaded transmit-receive antenna pairs. Data were obtained from one transmit-receive antenna pair as it was moved from a height of 29 cm to the dielectric surface at 1 mm increments. Direct transmission data were also obtained at the second antenna pair placed on the other side of the dielectric medium. Data were obtained from three different dielectric media possessing permittivities of 5.2, 10.6, and 80. Comparison of the frequency spectra of the direct-transmission waveforms for different transmitting antenna distances from the dielectric surface revealed a slight shift towards lower frequencies when the antenna enclosure was in contact with the surface. The direct-coupled waveform between transmitting and receiving antennas inside the same enclosure varied significantly over an antenna enclosure-surface distance range of 0 to 10 cm. the changes in the direct-coupling waveform appear to be largely due to the linear superposition of: (1) the direct arrival between the transmitting and receiving antennas, and (2) the surface reflection and associated surface reflection multiples. The waveform collected by the receiving antenna adjacent to the transmitting antenna was remarkably similar to the one-way transmitted waveform recorded at the receiving antenna on the other side of the block.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.