孔缝对内置带MSL电路板壳体耦合特性研究

Study of Slot on the Coupling Characteristics for the Shelled of Loaded PCB with MSL

因孔缝的存在屏蔽腔防护性能在谐振点处被大幅度弱化,现有文献多单以屏蔽效能(SE)作为测算点,对于电磁能量与PCB上MSL耦合而产生感应电流(Current)的计算没有给予足够关注。有鉴于此,建立内置带MSL的PCB开缝壳体等效计算模型,在模型有效性验证后,使用有限元法研究平面波激励下,MSL端接负载、孔缝尺寸、PCB尺寸及位置等参数变化对SE和Current的影响。结果表明:Current和SE虽然幅值变化不同,但曲线走势具有一定的对称性,尤其是谐振频点处;负载取值不同对结果没有影响;孔缝长宽尺寸变化对第二谐振有明显影响,取值增大频点左移是共性,且受长度影响更明显;PCB长宽尺寸增加,第一谐振左移是共性,且频移幅度受宽度影响更大,PCB宽度越大,第二谐振被激发出的可能性也变大;PCB等值靠近左壁,第一谐振等频右移,第二谐振等频左移。

Because of the existence of the slot,the shielding performance of cavity is weakened at the resonance point. The shielding effectiveness is often used as the measuring point in the existing literature. The calculation of the induction current for the coupling is not given enough attention. In view of this,the equivalent calculation model for shelled of loaded PCB with MSL is established. After model validation,studying the influence for SE and current due to the parameter changes such as load,slot and PCB. The results show：Although the amplitude varies,but the curve trend has certain symmetry,especially at the resonance frequencies;Different load values have no effect on the results;The change of the slot size have a significant effect on the second resonance,and the frequency shift to the left is the common character with increasing value;With the increase of PCB size,the first resonance shift to the left,and the shift range is more affected by the width. The greater the PCB width,the more likely the second resonance is to be excited;The PCB equivalent to the left wall,the first resonance shift to the right and the second resonance frequency shift to the left equal frequency.