oa Development of phased array ground penetrating radar for near surface exploration

We have confirmed the interaction among phased array antennas in our previous study. In this paper, we would like to discuss one of the powerful and practical schemes of using phased array antennas applied to near surface exploration using ground penetrating radar (GPR). GPR emits electromagnetic (EM) waves to the subsurface and to measure signals reflected back from buried anomalies for the estimation of the positions and shapes of the anomalies. Although phased array antennas could generate EM waves whose signal-to-noise ratio is superior to that emitted by the conventional GPR antenna, there has been a risk of the interaction among plural antennas could lower the signal-to-noise ratio due to electrical currents induced by magnetic field generated by the other antennas and it was necessary to confirm the level of the interaction or the unfavorable currents caused by the other antennas. We conduct a numerical simulation to evaluate the mutual coupling of each pair of phased array antennas to determine the best alignment of antennas in the design to maximize the level of emitted signals. We then conduct another simulation with heterogeneous ground model using our designed antenna in order to confirm the effectiveness of the phased array antenna in practice. Our results show that the phased array antenna enhances the signal-to-noise ratio compared to the conventional antenna and has a higher sensitivity to the targets located lateral to the survey lines with low interaction level between the neighboring two antennas. We conclude that the phased array antenna has a potential to be used as a new radar source for GPR.