An Improved MOM Approach to Determine the Shielding Properties of a Rectangular Enclosure With a Doubly Periodic Array of Apertures

The shielding properties of a rectangular enclosure with a doubly periodic array of apertures, exited by an obliquely incident and arbitrarily polarized plane wave is dealt with an improved method of moments (MOM) approach and mode-matching technique efficiently and accurately. Floquet waves for periodic structure are employed to represent the fields of the half-space, and the fields within the cavity are considered as superposition of waveguide modes. After enforcing the boundary conditions, MOM is used to obtain the shielding effectiveness and transmission coefficient. The proposed method has been successfully verified by a full-wave simulation tool CST and measurements. In our method, an arbitrary observation point is taken into account as well as higher order modes of the cavity. It is also found that all the resonant frequencies can be predicted from the transmission coefficient versus frequency curve.