A highly efficient, full-wave electromagnetic model and CAD of ortho-mode transducers built on a circular waveguide and supplied with step transitions in input rectangular waveguide ports is proposed. A discussion on the inherent limitations of the achievable performance and critical parameters is presented. The capabilities of the CAD program are demonstrated by the design of dual-band OMTs with identical and different input waveguides.

The opportunity of an effective usage of a stepped approximation for the calculation of cutoff frequencies and eigenfunctions of waveguides with complex cross-sections is shown. It is recognized that such an approach is productive for the analysis and optimization of polarizers based on sections of circular waveguides with rectangular ridges. The results of comparison with experimental data are represented.

A review of results obtained from the numerical simulation of electromagnetic characteristics of multislot irises placed into a rectangular waveguide are presented. The physical interpretation of scattering parameters of such irises as open waveguide resonators is proposed for explanation of their properties. This is accomplished by simultaneous excitation of high- and low-Q modes with a complex frequency. The simplest rejection section-a thin transverse single-slot strip-and bandpass filters with slots creating additional attenuation poles are proposed. Experimental data for rejection filters are presented.

A highly efficient, full-wave electromagnetic model and CAD of septum polarizers with a circular or square output waveguide is presented. The capabilities of the CAD program are demonstrated by the design of dualband septum polarizers, where the separation between the two bands is approximately 50%.

This paper presents a systematic approach for computer aided design of waveguide E-plane diplexers. The approach is based on the principle of equireflection three-ports and using the common junction as the constituent elements of the K-inverters of each channel filter. The method divides an E-plane diplexer in a number of key essential building blocks and adopts the best method for the analysis and synthesis of each key block This has led to a very accurate and efficient design procedure with minimum computation effort. The advantage of the proposed design procedure has been demonstrated by the implementation of several E-plane bifurcated and T-junction millimeter-wave diplexers. The design algorithms presented in this work can be implemented on a low end Pentium machine. An exact design of a diplexer requires no more than 10 min. (C) 1999 John Wiley Be Sons, Inc.

The paper is devoted to the method and results of design and analysis of evanescent mode lowpass filters (LPF) that may be used as higher frequency harmonic filters (up to the fourth harmonic). Configuration of LPF is based on shorten ridged waveguide sections (resonators) with a ridge profile varying along the longitudinal axis. The exact full-wave models are used for the obtaining of generalized S-matrices of all components, and analysis of LPF as a whole structure is carried out on the base of the generalized S-matrix technique.