3D migration of GPR array-antenna data

This study presents results obtained using a 3D migration algorithm on ground penetrating radar data collected with a switched antenna array. The results from the switched array are compared to similar x-y scanned data from a single pair of transmit/receive antennas. We use the Stolt wavenumber migration algorithm for 3D processing of the radar data. The migration is performed in the wavenumber domain, assuming constant wave velocity for waves travelling in the soil. This assumption gives sufficient image quality for shallowly buried objects, while retaining a low processing time. We present two data sets from a laboratory sandbox containing several buried targets: One data set was acquired as an x-y raster scan using a single pair of bowtie transmit/receive antennas, and the other data set is taken with the new switched antenna array. With the single antenna pair, the system can resolve the size and location of buried objects to within 5 cm in dry sand. Using the antenna array, the resolution is fully maintained, but the noise level is somewhat increased. The reasons for this are differences between the transfer functions of the individual antenna elements, distortion introduced by the RF-switches, and mutual coupling effects between the antenna elements which are not yet fully calibrated.