恒阻抗TEM喇叭天线设计关键问题研究

Study on the Design Problem for Constant Characteristic Impedance TEM Horn Antenna

恒阻抗TEM喇叭天线具有沿轴线方向特性阻抗为一恒定值的特点,所以喇叭内的反射损耗非常小,常用于超宽带电磁脉冲的辐射与接收。为了提高恒阻抗TEM喇叭天线远场主射方向脉冲峰峰值,通过数值仿真和实验测试研究了天线口径以及特性阻抗值与远场主射脉冲的关系。研究发现,天线沿主轴方向长度一定时,脉冲源通过50Ω同轴线直接向天线馈电,远场主射方向脉冲峰峰值先随天线口径增大而迅速增加,当口径达到某一值时,脉冲峰峰值达到最大值,如果继续增大口径,脉冲峰峰值开始缓慢下降。对于各个特性阻抗值不同的TEM喇叭天线,当它们分别选取上述峰峰值最大对应的口径时,280Ω的恒阻抗天线远场主射方向脉冲峰峰值最大。

TEM horn antenna with constant characteristic impedance（CCI TEM horn antenna） as one kind of ultra-wideband（UWB） antennas has been widely used.As the characteristic impedance of such antenna is a constant value along the axial direction,the reflection loss in the horn is very low.In order to elevate the CCI TEM horn antenna＇Vpp（peak to peak value of the far-field pulse in the axial direction）,the relationship between the Vpp and the aperture as well as characteristic impedance is analyzed by numerical simulations and experimental measurements.If the CCI TEM horn antenna is fed by a 50Ω coaxial cable and its length along the axial direction is a constant value,the maximum Vpp of such antenna can be reached with optimal apertures.Also,when optimal aperture is chosen for the antenna with different impedance values,the Vpp of such antenna with characteristic impedance 280Ω is the maximum.