Quasi-optical diplexer by rectangular metallic mesh

A Frequency-Selective Reflector Surface (FSRS) using rectangular metal meshes to realize a broadband quasi-optical filter with polarization-independence is studied. A theoretical analysis shows that the transmission characteristics of a rectangular metal mesh can be analyzed most accurately by an electromagnetic scattering and diffraction approach based on the mode-matching method. By arranging the rectangular metal mesh in a brick-type manner, the anomalous antiresonance for the TM incidence can be placed at a frequency higher than the resonant frequency of the single mesh. This reduces the difference in transmissions characteristics for TE and TM incidence. Experimental results with an FSRS using this brick-type metal mesh are found to agree with the theoretical ones.