Theoretical and experimental near-field characterization of perforated shields

The shielding performance of an infinitely large, periodically perforated plane shield is investigated, both theoretically and experimentally. Attention is focused upon the near-field characterization by using two loop antennas at both sides of the shield. The electromagnetic coupling between the two loops is analyzed numerically using a plane-wave spectral representation of the radiated field and the method of moments. Comparison of these numerical results with near-field measurements yields a very good agreement up to high frequencies. The predicted classical far-field shielding effectiveness drastically overestimates the near-field shielding performance of the screen