Design of bow-tie antenna with high radiating efficiency for impulse GPR

High radiating efficiency of antenna is very crucial for GPR applications. However, the bow-tie antenna, which is widely used in impulse GPR, has very low radiating efficiency because remarkable energy fed into antenna is radiated as the form of end reflection. In this paper, we study how to design bow-tie antenna with high radiating efficiency for impulse GPR. We find that, if the bow-tie antenna is excited by a bipolar pulse, the radiation efficiency can be significantly improved by utilizing the energy in end reflections. And the improvement is implemented by optimizing the antenna length to superpose the main pulse with the end reflection of a radiated pulse.