DESIGN OF WAVE-GUIDE E-PLANE FILTERS WITH ALL-METAL INSERTS BY EQUAL RIPPLE OPTIMIZATION

An optimization based approach to the design of E-plane filters is des cribed. An optimization procedure based on Cohn's equal ripple optimiz ation is developed. This vector procedure has several advantages over the general purpose optimization routines previously applied to the de sign of E-plane filters. The problem of local minima does not arise. O ptimization is carried out with respect to the Chebyshev (or minimax) criteria. Less frequency sampling and therefore less calculation of th e electrical parameters of E-plane discontinuities is required. The de sign of a symmetrical E-plane filter is considered. Higher order mode interaction between E-plane discontinuities is not included in the des ign. For the design example considered this is shown not to be signifi cant. A numerically efficient method, requiring only real scalar arith metic, for calculating the insertion loss of a symmetrical cascade of lossless symmetrical 2-ports is employed. Measurements on a fabricated filter confirm the accuracy of the design procedure.