An Analytical Method for Shielding Effectiveness of Complex Metallic Cavities Based on the BLT Equation
DOI:
https://doi.org/10.13052/2025.ACES.J.401108Keywords:
Electromagnetic topology (EMT) theory, equivalent circuit method, general Baum-Liu-Tesche (BLT) equation, shielding effectiveness (SE)Abstract
A hybrid analytical method integrating the equivalent circuit method, electromagnetic topology theory, and the generalized BLT (Baum-Liu-Tesche) equation is proposed. This method systematically incorporates plane-wave incidence-angle effects and lossy conducting material properties and is further extended to heterogeneous configurations such as stepped cavities and series-parallel hybrid cascaded three-layer cavities, thus enabling rapid yet accurate assessment of both the shielding effectiveness (SE) and resonant behavior in complex metallic cavities. First, a model based on equivalent circuit theory is established. Next, a corresponding signal flow graph is established using electromagnetic topology theory, after which the generalized BLT equation is derived to compute the SE. Comparisons with CST full-wave simulation results demonstrate that the proposed method achieves a significant improvement in computational efficiency while maintaining high accuracy. It effectively accommodates arbitrarily eccentric apertures, aperture arrays, and arbitrary observation points, and can rapidly and accurately predict the SE and higher-order resonant frequencies, even at elevated frequencies. This work provides a simple and efficient analytical method for analyzing the SE of various heterogeneous and complex metallic cavities.
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