Shielding Effectiveness of 1-D Periodic Composite Screens in the Presence of Electric Line Sources: Full-Wave Analysis and Limits of Homogenization

The near-field shielding effectiveness of composite screens characterized by spatial periodicity along one dimension is investigated in the presence of an electric line source (i.e., an aperiodic source) placed in proximity of the screen. The metal strip grating and the wire-medium screen supported by a dielectric board are studied as examples of one-dimensional periodic screens. Both full-wave analyses and approximate homogeneous models are adopted in order to investigate the limits of the homogenization techniques for the study of the interaction between a finite source and a periodic screen. Moreover, differences in shielding-effectiveness values for such periodic structures are discussed when considering finite- source or plane-wave excitations.