加装印刷电路板的圆孔阵矩形机壳屏蔽效能

Shielding effectiveness of PCB loaded rectangular enclosure with circular-aperture array

为评估矩形金属机壳抗外部电磁干扰的能力,建立加装印刷电路板(PCB)有圆孔孔阵矩形机壳的波导等效电路模型,导出其电场屏蔽效能的简洁表达式,提出一种简单高效的新方法,对于没有加装印刷电路板的机壳,该方法的简化结果与现有文献结果完全一致;对于加装PCB的机壳屏蔽效能,该方法计算结果与CST仿真结果良好吻合。结果表明:电场极化方向与孔阵长度方向平行,同其与孔阵长度方向垂直比较,前者屏蔽效能显著优于后者;所考虑的频率范围内,加装PCB可以显著提高机壳的屏蔽效能;正交排列孔阵的屏蔽效能优于交错排列孔阵的屏蔽效能;保持孔阵中孔数目不变,孔间距越大,屏蔽效能越高。

With the purpose of evaluating the ability for a metallic rectangular enclosure with an array of circular apertures and a printed circuit board（PCB） against the external electromagnetic interference, a waveguide equivalent circuit model was established, the analytical formulation of shielding effectiveness（SE） was derived from the equivalent circuit, and a simple and higheffective approach was proposed. In the case of the enclosure without PCB, the approach is identified with that in the reference. With respect to the SE of the PCB loaded enclosure, the calculated results using the present approach are in well agreement with those obtained by commercially available numerical tool CST. The results show that the comparison between electric field orientations parallel and perpendicular to the length direction of the aperture array was made, and the former has an advantage over the latter in SE; the SE is evidently improved by means of loading the enclosure with a PCB; the SE of a 90°aperture array configuration is much better than that of the staggered configuration; the larger the aperture spacing is, the better the SE is, when the number and configuration of apertures are constant.