Analysis of a ridge waveguide family based on subregion solution of multipole theory

The subregion solution of multipole theory(MT) is presented as a new approach for the analysis of propagation characteristics of a ridge waveguide family. The complicated field domain not satisfying the MT series expansion condition is treated as a combination of several simple field regions satisfying the MT series expansion condition, and the solution of the governing partial differential equation is represented by the generalized analytical MT formula. Representative computational examples including L-shaped, single-ridge, double-ridge, trapezoidal-ridge and quadruple-ridge waveguides are given to validate the theory and to demonstrate the accuracy and flexibility of the MT method.