Shielding effectiveness of cylindrical enclosures with rectangular apertures

This paper presents an efficient numerical method to predict the shielding effectiveness of a cylindrical enclosure with a rectangular slot. The problem is initially divided into two parts using the field equivalence principle: one is the half free space with a plane wave illumination and a magnetic current on the aperture surface and the other is the rectangular-to-circular waveguide junction with one end of the circular waveguide being shorted. The reflection coefficient of the waveguide junction is calculated by the mode-matching method and the magnetic field in the exterior region is modelled using a mixed potential integral equation. The unknown coefficients of the electromagnetic field are obtained by matching the tangential magnetic field along aperture surface. Numerical results are presented and compared to those obtained by Ansoftpsilas high frequency structure simulator (HFSS). Parametrical studies are also conducted for the effect of the location and size of the aperture on the shielding effectiveness.