Use end reflections to improve the radiation efficiency of bow-tie antenna

The bow-tie antenna, which is widely used in impulse ground penetrating radar (GPR), has very low radiating efficiency. It is because that, nearly 70% of the radiated energy exists as the form of end reflection, which is harmful to probe objects. In order to keep the probing ability, the remarkable energy in end reflections is usually dissipated by resistive loading. We find that, in this paper, if the exciting pulse is bipolar and monocycle, the radiation efficiency can be significantly improved by utilizing the energy in end reflection. And the improvement can be implemented by optimizing the antenna length. The proposed method is validated by simulated experiment. And the results show that, the radiation efficiency can be increased by 100% compared with an antenna with infinite length. Additionally, the proposed method is easy to be carried out in applications and of great use.