The Field Displacement Filter - A New Family of Dissipative Waveguide Filters

Rectangular waveguides with a full-height dielectric slab are frequently used in isolators and phase shifters. Numerical solutions to the fields have been obtained for the slab centrally located. It is found that with increasing frequency the power flow is more and more confined to the dielectric slab. The electric field distribution is plotted with frequency as a parameter. According to a suggestion by H. Seidel (US Patent No. 2,963,661) this effect can be used to separate frequencies. Coupling apertures in the empty part of the guide will couple only at low frequencies; however, a sharp cutoff cannot be expected.