刘雪明　廖成　冯菊

摘 要： 指数渐变TEM喇叭沿主轴方向长度一定时，主射方向上辐射脉冲峰峰值随口径高度递增，当辐射脉冲峰峰值到达最大值后，辐射脉冲峰峰值随着口径高度递减，并且辐射脉冲波形发生畸变。为了分析响应波形畸变原因，基于等效开路传输线模型给出指数渐变TEM喇叭脉冲响应的近似表达式，并且结合指数渐变TEM喇叭内部的电磁能量流动过程修正辐射脉冲表达式。理论分析表明，指数渐变TEM喇叭辐射脉冲由两个分量叠加而成，并且这分量之间存在的相对时延与高度渐变线的相对变化率正相关，过大的相对时延会使辐射脉冲的波形发生畸变，从而导致辐射脉冲峰峰值小于同尺寸线性渐变TEM喇叭的辐射脉冲峰峰值。利用电磁仿真软件得到相同尺寸的指数渐变TEM喇叭与线性渐变TEM喇叭的辐射脉冲波形，通过二者之间的对比验证理论分析的正确性。

关键词： TEM喇叭； 指数渐变线； 脉冲响应； 相对时延

中图分类号： TN822.8?34 文献标识码： A 文章编号： 1004?373X（2014）03?0084?04

Analysis on waveform distortion of the radiation pulse

with exponential tapered TEM horn

LIU Xue?ming， LIAO Cheng， FENG Ju

（Institute of Electromagnetics， Southwest Jiaotong University， Chengdu 610031， China）

Abstract： When the main axial length of the exponential tapered TEM horn is constant， the peak?peak value of the radiation pulse increases with the aperture height， after the maximum is reached， the peak?peak value of the radiation pulse decreases with the aperture height and the distortion would occur to the radiation pulse waveform. In order to analyze the causes of the waveform distortion， an approximate expression of pulse response with exponential tapered TEM horn is given based on the equivalent open circuited transmission line model， and the expression is modified by tracing the electromagnetic energy flow in the TEM horn. Theoretical analysis results show that the radiation pulse consists of two components， in which the relative time delay and relative change rate of the transition line have positive correlation. When the relative time delay is too large， the distortion will occur， thus the peak?peak value is lower than that of linear tapered TEM horn with the same size. The wave form of exponential tapered TEM horn and linear tapered TEM horns with the same size are obtained by electromagnetic simulation software， comparison validation proved the correctness of the theoretical analysis results.

Keywords： TEM horn； exponential tapered line； pulse response； relative time delay

0 引 言

TEM（Transverse Electro Magnetic）喇叭天线作为常用的时域天线被广泛研究，并且以单个天线、天线阵列单元、反射面天线馈源等形式用于高功率微波武器、探测、通信等众多领域。阻抗加载技术使线性渐变TEM喇叭上的电流表现为行波特性，消除反射导致的响应波形拖尾[1]。王磊等通过数值计算和实测，给出线性渐变TEM喇叭沿主轴方向长度一定时的最佳口径[2]。指数渐变TEM喇叭采用外形控制法控制天线阻抗代替阻抗加载，提高了TEM喇叭天线的辐射效率[3]。……