Efficient analytical method for the shielding effectiveness of an apertured enclosure based on the BLT equation

Abstract

An efficient analytical method based on the Baum–Liu–Tesche (BLT) equation has been developed for predicting the shielding effectiveness (SE) of an apertured enclosure excited by an external plane wave. First, the equivalent circuit and the signal flow graph are constructed, which helps understand the energy transmission of the enclosure. Then, the SE is obtained by using the generalised BLT equation, and the proposed analytical method is employed to analyse the effect of various parameters on the SE. Finally, the analytical method is extended to handle the enclosure with an aperture array, an enclosure with apertures at the opposing walls and two cascaded enclosures. The analytical method has been successfully verified by the CST over a wide frequency band of 0–3.0 GHz, which consumes less time than conventional numerical methods. Besides, whatever the condition of the enclosure or the aperture is, the analytical method can predict the SE and higher-order modes at higher frequencies accurately.