Ground Penetrating Radar: Antenna Effects and Patterns.

Abstract

In the spring of 1998, 816 lines of Ground Penetrating Radar (GPR) data were recorded to determine the effects of antenna orientation on reflection data. The large amount of data collected allowed for the investigation of many variables that affect GPR data. One of the few variables that can actually be changed in field situations, (in other words not inherent to the target) is antenna orientation. The importance of different antenna orientations is demonstrated within. After the data was processed and put into visual form, comparisons could be made, and conclusions and generalizations were possible based upon them. The requirements for the detection of a target include the following: 1) a sufficiently strong input wave is needed, 2) the impedance contrast needs to be high enough for a reflection, 3) the target size needs to be sufficient for the burial depth, and 4) other objects must not interfere. The effects of target size, target type, burial depth, offset, and antenna orientation are shown. Polarization, and therefore antenna orientation, is shown to have a large affect on the resulting data quality. In most situations best results were obtained with the antennas oriented perpendicular to the traverse of the line.