Computer Analysis of Arbitrarily Tapered Rectangular and Double-Ridged Waveguides

摘要

The presented work was motivated by a need for high-power, wideband waveguide transitions with low VSWR to be used as output couplers of microwave tubes. The work consists of a computer analysis of arbitrarily tapered waveguides with ridged and unridged cross sections. The analysis combines coupled mode theory with numerical methods to solve nonuniform waveguide problems. The coupling coefficients in Solymar's form of the generalized telegraphist's equations are computed from numerically obtained eigenvalues and eigenfunctions. The scattering matrix for a section of tapered waveguide is obtained by solving the coupled differential equations once for each initial mode amlitude in a complete orthogonal set. The method can be applied to multimode problems with arbitrary cross sections and tapered shapes. The technique's usefulness is demonstrated for dominant mode rectangular and ridged waveguides having linear and cosine tapers. It is shown that the theoretical prediction of VSWR agrees well with experimentally obtained results.