A Hybrid HBMoM-HGEMT Method for Broadband EM Coupling Analysis of Feedthrough Transmission Line Networks With Shielding Enclosures

The broadband electromagnetic (EM) coupling problem of feedthrough transmission line networks (TLNs) with shielding enclosures, spanning frequencies from low to gigahertz, is common and urgent. However, a single analytical or numerical method often struggles to achieve both accuracy and efficiency. In response, we developed the numerical high-order basis function method of moments (HBMoMs) and the analytical hierarchical graph-EM topology (HGEMT) solver, respectively, and successfully combined their strengths to form a novel hybrid HBMoM-HGEMT method. In this scheme, HBMoM calculates the open-circuit voltage Voc and the input impedance Zin of the field-to-line coupling equivalent circuit, while HGEMT computes the conduction along TLNs. Four progressively designed cases verify the advantages of the hybrid method. Case I demonstrates the accuracy of HBMoM for field-to-line coupling computation. Case II demonstrates the efficiency of HGEMT for conduction calculation. Case III experimentally validates the equivalent circuit model of broadband EM coupling. Case IV provides the comprehensive validation by comparing EM responses of a shielded feedthrough TLN system using three methods, with the hybrid method achieving comparable accuracy in only 0.36 versus 2.1 h for field expertise kernel optimization (FEKO) and 0.77 h for CST Cable Studio. Overall, the proposed hybrid method combines the full-wave precision with the transmission line (TL)- based efficiency, providing a powerful solution for broadband EM coupling analysis of TLN-involved systems.