A Study of Dielectric Covered Shunt Slots in a Waveguide

The purpose of this study was to experimentally determine the effects of placing dielectric covers of various thicknesses over a shunt slot in a waveguide. Slot lengths L and displacements x were chosen so that the data cover the waveguide bandwidth for dielectric constants ϵ' from ϵ' = 1 to ϵ' = 4. Utilizing the measured data, formulas are developed for the mean values of slot conductance and resonant frequency for cover thicknesses greater than λϵ'/4. In addition, it is shown that plane wave theory gives a bound on the conductance variation for covers thicker than λϵ'/4. Finally, pattern and VSWR measurements of linear arrays of dielectric covered slots designed with single slot data give predictable results.