Modeling Electromagnetic Field Coupling Through Apertures for Radio-Frequency Interference Applications

• Published in: IEEE transactions on electromagnetic compatibility 2015-10, Vol.57 (5), p.1037-1048
• Main Authors: Ren, Liehui, Fan, Jun
• Format: Article
• Language: English
• Subjects: Apertures; Cavity resonators; Current density; Electromagnetic field coupling through aperture; Electromagnetic interference; Ewald's transform; Exteriors; Green's functions; Green's functions in a cavity; Holes; Impedance; impedance network; Joining; Magnetic domains; metallic enclosure; method of moments (MoM); mixed potential integral equations (MPIEs); Networks; Ports (Computers); radio-frequency interference (RFI); segmentation method; Surface impedance
• ISSN: 0018-9375; 1558-187X
• DOI: 10.1109/TEMC.2015.2424248

Electromagnetic field coupling between a digital platform and a radio-frequency antenna through an aperture represents one of the typical coupling paths responsible for radio-frequency interference (RFI) issues in mixed-signal systems. Conventional approaches of modeling radiation through an aperture and evaluating the shielding effectiveness of a metallic enclosure with apertures for classic electromagnetic interference (EMI) applications are not sufficient to handle modern RFI challenges. This paper discusses a segmentation method, together with impedance network representation, employed to divide the enclosure EMI problem into exterior and interior problems. With a port definition based on the vector roof-top basis function, the impedance network for the exterior domain was rigorously formulated using a method of moments solution for mixed potential integral equations. The impedance network for the interior domain was computed using the cavity method based on the analytical formula of 3-D Green's functions in a rectangular cavity. Connecting a pair of impedance networks yielded the overall impedance relationship between the interior port and the exterior port. Ewald's transform was used to accelerate the computation of Green's functions in a cavity with metallic walls, which yielded fast convergence of the series summation in Green's functions. Good agreement with a commercial full-wave tool validated the proposed approach.