An Analytical and Experimental Investigation of Planar Discontinuities in Coaxial Waveguides.

Abstract

Abstract : An integral equation approach has been developed for treating a large class of planar discontinuities in coaxial waveguides. The technique can effectively treat single and multiple discontinuities with no constraints on frequency or relative location. The integral equations are formulated with the transverse component of electric field in the aperture of each discontinuity as the unknown quantity. A numerical solution procedure is described which allows a choice of both the number of subsectional expansion pulses employed in each aperture and the number of terms evaluated in the modified higher-order-mode series. Once a solution for the electric field in each aperture is obtained, straightforward procedures may be used to compute the admittance of any discontinuity or the field anywhere in the waveguide. Two sets of coaxial waveguide/cavity structures have been constructed and an extensive program of experimental measurements of cavity admittance and field components at cavity walls has been pursued. The measured results have been compared to integral equation calculations of the same quantities to verify the accuracy of the approach. The integral equation approach has demonstrated a capability for extreme accuracy when sufficient expansion pulses and series terms are used and offers the opportunity for computing the transient response of waveguide discontinuities by means of a transform technique. (Author)