利用拖尾能量提高蝶形天线辐射效率

蝶形天线在探地雷达中已有广泛的运用,但其辐射效率不高的问题一直存在。究其原因,主要是将近70%的辐射能量是以有碍目标探测的拖尾的形式存在。为了保证探测性能,传统上可观的拖尾能量往往以阻抗加载的方式被吸收掉。本文研究发现,当选择双极性单周波作为激励脉冲时,通过优化天线长度可以实现拖尾能量的有效利用,从而显著地提高蝶形天线的辐射效率。仿真实验结果表明,在较远的探测距离上本文方法可以将辐射效率提高近100%。通过实测实验进一步验证了本文方法的有效性。此外,本文所提的方法易于工程实现,工程应用价值十分明显。

Improve the radiation efficiency of bow-tie antenna by exploiting the energy in end reflections

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 simulated results show that, the radiation efficiency can be increased nearly 100%. And the measured results validate the proposed method again. Additionally, the proposed method is easy to be carried out in applications and of great use.