Field Experiments Using a Pulse Directional Borehole Radar System with a Dipole Array Antenna

A new design for a pulse directional borehole radar with a dipole array antenna is proposed and tested. In this radar, a pulse generator excites a pulse, with peak voltage of 110 V and low jitter at a feeding point of the transmitter. The receiver measured the difference of arrival times at several receiving dipole elements to estimate the direction of the arrival wave. We compensated for time delays due to the cables which connect the dipole elements. Field experiments were carried out with the pulse directional borehole radar in tuff; the system received a reflected wave from a metal cylinder located several meters from the radar antenna. After the cable delay compensation, we successfully estimated the 3-D location of the metal cylinder. The results offield measurements using a stepped-frequency directional borehole radar are also included for comparison.