Finite element analysis of an array of cylindrical rods or rectangular bars between ground planes (Q1387904)

Microwave filters consisting of arrays of cylindrical rods or rectangular bars located between parallel ground plates are constructed. A design method for their analysis is presented. Quasi TEM mode propagation along such structure is considered. The analysis is based on finite and infinite element methods using a functional procedure along with a minimizing energy functional of Laplace equation. A normalized Maxwellian capacitance matrix per unit length is obtained for wide ranges of thickness, diameter, and spacing of the rods and bars. Characteristic impedances are plotted and compared with those by \textit{E. G. Cristal} [IEEE Trans. Microwave Theory Tech. MTT-12, 428-439 (1964)]. An agreement is found. The method can be extended to inhomogeneous cylindrical structures.