指数渐变TEM喇叭辐射脉冲波形畸变分析

Analysis on waveform distortion of the radiation pulse with exponential tapered TEM horn

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。

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 wave-form distortion,an approximate expression of pulse response with exponential tapered TEM horn is given based on the equiva-lent 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 expo-nential 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.