有孔矩形腔屏蔽效能的传输线法分析

Analysis on shielding effectiveness of rectangular cavity with apertures by transmission line method

首先介绍了用传输线法(transmissionlinemethod,TLM)分析有孔矩形腔屏蔽效能的基本原理,然后将基本公式作进一步扩展,使其能计算圆孔、多孔洞以及在任意极化方向时的情形。仿真结果表明:当频率低于主谐振频率时,离孔缝越近,耦合进的电磁能量越大;当处于谐振频率时,屏蔽腔与孔形成共振,屏蔽效能很低甚至为负,而且腔体内任何空间都如此;屏蔽效能随极化角度的递增而递减,低频段的屏蔽比高频段要好;对于相同面积的孔洞,单孔洞的屏蔽效能比多孔洞的屏蔽效能要差,孔洞越多,屏蔽效果越好,而圆形孔(等同于方形孔)的屏蔽效果最好。

This article firstly introduces the basic theory of transmission line method (TLM) which is used to analyze shielding effectiveness of rectangular enclosure with apertures, then expands the fundamental formulas to deal with cases of round hole, multi-holes, and arbitrary angle of polarization. Simulation results indicate: (l) when the frequency is under dominant resonant frequency, the closer to the enclosure, the more coupling energy; (2) under resonant frequency, resonance appears between the aperture and the enclosure, which results in low even negative shielding effectiveness in the cavity; (3) shielding effectiveness decreases when polarization angle increases, and shielding of low frequency is better than that of high frequency; (4) for the same areas, shielding effectiveness of single-hole is worse than that of multi-holes, and the more holes, the better performance, and the round (equal to square) hole is the best.