Migration using multi-configuration GPR data

Due to the radiation pattern of the GPR antennas, the amplitude of the reflection is not only dependent on the distance between the target and the antennas, but also on the angle of orientation between the antennas and this target. Alford rotation is applied to this radiation pattern of the antennas, and used to extract the location of the origin of the reflected wavefield. This information is used to improve the migration scheme. In conventional migration schemes, recorded data are migrated to all angles. In this method, instead the recorded data are migrated to certain grid points only. This makes the migration algorithm faster and more accurate. This Alford migration method is applied to synthetic data and is shown to be successful below a noise level of about 1% of the amplitude level of the data. A higher level of noise results in an inaccurate estimate of the angle to the location of the target and the signal to noise level to decrease. The result can be improved by migrating over a limited sweep of angles around the estimated angle. Application of this method to field data collected at a controlled test site has shown poor results, as there was too much noise present in the data and errors might occur due to dispositioning of the antennas.