Full-wave analysis of broad wall slot's characteristics in rectangular waveguides

A rigorous analysis of the resonant characteristics for a broad wall waveguide slot by using the finite-difference time-domain method is presented. Four types of slots including a radiating longitudinal shunt slot, a longitudinal/transverse coupling slot, a centered-inclined coupling slot and a compound coupling slot are analyzed. Lots of slot characteristics such as the resonant length, scattering parameters and normalized admittance in different offsets, tilt angles or slot sizes are obtained. Because the shape of slots is a rectangle with rounded ends in practical fabrication, an accurate modeling and computation for the slots with rounded ends is implemented, and the resonant lengths calculated coincide well with the Stegen's measured data and method of moments results. From these computed results, it is found that all the resonant characteristics of the slots with rounded ends are significantly different from those with normal rectangular ends.