An Improved Circuital Method for the Prediction of Shielding Effectiveness of an Enclosure With Apertures Excited by a Plane Wave

An efficient circuital model is developed to predict the shielding effectiveness of an enclosure with an aperture array excited by a plane wave. First of all, the impedance of the aperture array is expressed as a function of the spacing between apertures, the radius of apertures, the incident angle, and the thickness of the perforated plate. Then, a multiple modes equivalent circuit method is proposed to evaluate the shielding effectiveness of the enclosure at frequencies up to multiple resonances region. Finally, the efficiency and accuracy of the method are demonstrated by comparing its results with analytical results from other equivalent circuit methods and numerical results from the transmission-line modeling method. The method outperforms the traditional equivalent circuit methods in that it takes into account several crucial geometrical parameters, the properties of the incident plane wave, the mutual coupling between apertures, and multiple modes propagation effect at the same time, thus having better accuracy. Meanwhile, the method provides a reasonable accuracy with a low computational burden, as compared with more complex numerical methods.