An order-reduced volume-integral equation approach for analysis of NRD-guide and H-guide millimeter-wave circuits

An order-reduced volume-integral equation approach is proposed for modeling and analyzing of nonradiative dielectric (NRD)-guide and H-guide millimeter-wave circuits that involve arbitrarily shaped planar geometry and inhomogeneous dielectric. A half-sinusoidal vertical variation of fields is used so that the discretization of current for the volume-integral equation is made in the parallel plane. Combined basis functions of propagating and local modes are used in the Galerkin´s method of moments on the basis of spectrum analysis of the NRD-guide and H-guide. A vertical integration in the space domain is carried out analytically and a first-order Green´s function with m=1 is developed. The solution for the volume-integral equation in modeling NRD-guide and H-guide circuits is then reduced to a two-dimensional planar problem. This technique can be applied for calculating the characteristics of various waveguide components and multiport circuits such as resonant frequencies and S-parameters. The framework of this technique is demonstrated through its application to an NRD-guide open-end. In addition, an H-guide open-end, three types of resonators, and three-pole gap-coupled NRD-guide filters are modeled and analyzed. The results are in good agreement with the measurements and results obtained by other methods.