利用电磁场模拟软件模拟了BJ100矩形开口波导的增益特性,探讨了法兰和波导长度对矩形开口波导增益的影响,得出了开口波导增益随波导长度以半波长为周期振荡的规律。为了减小增益随频率的振荡,抑制法兰对开口波导增益的影响,采用在波导外壁宽边贴覆吸波材料的办法。数值模拟表明:在波导外壁宽边贴上吸波材料后,增益随频率振荡的现象减弱或消失,矩形开口波导方向图的主瓣变宽,中心的增益值最大,满足高功率微波辐射场测量中使用的要求。

The gain of the open-ended rectangular waveguide was studied and the effects of flange on the gain of waveguide were discussed. The gain of BJ100 was calculated by an electromagnetic field simulation code. It is found that the period of the gain fluctuating with waveguide length is half wavelength. Then in the simulation,the outer wall of the waveguide was pasted with absorber to eliminate the effects of flange on the gain. The numerical simulation shows that this method weakens or even eliminates the dependence of gain on frequency,and the major lobe of the directional pattern becomes much wider with a peak in the center.