钻孔雷达全向天线的设计与分析

根据钻孔雷达全向天线的设计要求，为减少天线的结构尺寸增加带宽，设计了一种新型电阻加载全向天线。通过理论分析和数值优化，选择了较优的结构尺寸，得到了较佳方向图和带宽。天线外径为65 mm，使用10 mm厚天线罩封装后外径为85 mm；天线的S11小于-10 dB频带为70~260 MHz，带宽约190 MHz。该天线的带宽超过100 MHz，中心频率处增益大于-3 dB，辐射电场脉冲波形拖尾小于主峰幅度1/5，方向图在H面为全向。基于矢量网络分析仪的天线特性测量结果与数值计算结果基本一致，结果表明设计的天线能够满足钻孔测井雷达系统小尺寸宽带的要求。

Design and analysis of omni-antenna for borehole radar system

The borehole radar is a new method in borehole geophysical detection. In order to reduce the antenna structure size and increase the bandwidth, we designed a new resistive loading omni-directional antenna according to borehole radar requirements. Through theoretical analysis and numerical optimization, we selected the better structure, the antenna had good radiation pattern and bandwidth. The outside diameter of the antenna was 65 mm. The outer diameter was 85 mm, using a 10 mm tube encapsulated. S₁₁ of the antenna was less than -10 dB in the frequency band 70~260 MHz, with 190 MHz bandwidth. The center frequency gain was greater than -3 dB, and the radiation electric field pulse waveform tailing was less than 1/5 of the main peak amplitude, the pattern in the H-plane was omnidirectional. The measurement results of antenna characteristics using the vector network analyzer agree well with the numerical results. The results show that the design of the antenna can meet the requirements of the small size of broad borehole radar system.