Summary
International Symposium on Antennas and Propagation
2010
Session Number:3TF4
Session:
Number:3TF4-1
Analytical Prediction of Shielding Effectiveness of Rectangular Enclosures with Rectangular Apertures under Normal Incidence
Weiye Zhong, Zhongxiang Shen,
pp.-
Publication Date:2010/11/23
Online ISSN:2188-5079
Summary:
As wireless communication becomes explosively popular, metallic enclosures are usually employed in electromagnetic compatibility (EMC) design to keep electronic equipment from being affected by electromagnetic interference (EMI). However, these enclosures usually consist of various apertures used for ventilation or cabling purposes. Shielding effectiveness (SE), which is measuring the shielding efficiency of a metallic enclosure, is defined as the ratio of field strength with enclosure present to field strength with enclosure absent. In the past, a variety of analytical and numerical techniques were proposed to predict the SE of a rectangular metallic enclosure with different apertures [1]-[4]. In [1], the transmission line theory based on the dominant mode approximation was used to obtain an analytical solution to predict the SE. Various numerical methods [3, 4] can solve problems of complicated structure, but they normally require expensive computational resources. In this paper, the Bethe-Cohn aperture coupling theory is utilized to analytically calculate the electric fields inside the enclosure and to accurately predict the SE of rectangular enclosures with rectangular apertures. Bethe [5] investigated the coupling through a small circular aperture in a conducting wall of zero thickness based on equivalent electric and magnetic dipole moments. An extension of Bethe’s work was developed by Cohn [6] enabling the theory to be applicable to large apertures. It is demonstrated that our computed results for SE based on the Bethe-Cohn aperture coupling theory are in good agreement with measured and calculated results available in the literature.