Quasi-optical waveguide filters for millimeter and submillimeter wavelengths

Quasi-optical filters consisting of iterations of dielectric slabs housed in oversized rectangular waveguide are described. Filters consisting of dielectric slabs separated by air of the same electrical length have been analyzed and constructed for the cases of normal incidence (two-port filters) and 45° incidence (four-port filters). The two-port filters have low-pass properties while the four-port filter has simultaneous low and high-pass properties. Experimental data on 9 mm and 0.9 mm models have shown good agreement with the theory, thus demonstrating their use as filters for millimeter and submillimeter wavelengths.