Leonid A. Rud

Automatic electromagnetic solvers based on mode-matching, transverse resonance, and S-matrix techniques

The main goal of the paper is to present a new generalized mode-matching (GMM) approach to both mode bases and S-matrices calculation of complicated waveguide circuits. Development of the GMM procedures makes it possible to realize totally automatic algorithms for a wide set of configurations avoiding a specialized analytical treatment of each new boundary-value problem. Moreover, the background for linking up the interface tools of a circuit geometry specification and editing is provided by the GMM approach together with the special algorithms for recognizing the object configurations and for data preparation. The class of objects that can be calculated by the suggested approach includes any WG circuits with metal boundaries specified in the Cartesian coordinate system or with the smooth boundaries that may be replaced by a staircase surface. The corresponding electromagnetic solvers are closer to the software based on the mesh methods in generality, in the same time saving the high accuracy and computation speed typical for highly specialized mode-matching procedures.

Evanescent-mode ridged waveguide bandpass filters with improved performance

New types of evanescent-mode bandpass filters based on the ridged waveguide sections are considered. Insertion of additional inductive strips between the ridge sections enables one to reduce the longitudinal filter size, increase the cross section of the ridged waveguide housing, and achieve a sufficient improvement of stopband characteristics. Results of designing the millimeter-wave filters and comparison with the measured data are presented.

Spectral approach to the synthesis of bandstop filters

A nontraditional approach to the synthesis of bandstop filters (BSF) based on the analysis of the spectrum of complex eigenfrequencies of multimode resonators forming a filter is described. Two types of BSF resonators, which are formed by cross-section enlargements of a finite length of a rectangular waveguide in E- or H-plane, are considered. It was shown that a BSF of the first type had no spurious stopbands and practically did not introduce a loss in the passband. The high accuracy of the filter design is confirmed by the experimental data. >

Two notched band two post waveguide section

In this paper a two post rectangular waveguide section is presented. The posts are located side by side in a guide cross-section. The waveguide section provides a frequency response with two independently controllable notched bands. Each rejection frequency is tuned by a changing the height of one of two posts, whereas a rejection bandwidth is defined mainly by a post width.

Fast full 3D EM CAD of waveguide units based on the generalized mode matching technique

A unique 3D EM solver based on the generalized mode matching technique (MMT) and aimed to solve the problems of analysis and synthesis of a wide class of passive devices is presented. The high efficiency of the CAD software will be demonstrated at some typical examples.

THE MODE-MATCHING TECHNIQUE AND FAST NUMERICAL MODELS OF ARBITRARY COORDINATE WAVEGUIDE OBJECTS

A new algorithm based on two versions of mode-matching (MMT) approaches is proposed for solving the boundary value problems associated with arbitrary waveguides or cavities having piece-wise coordinate surfaces. The solutions are initially based on a pre-processing procedure aimed for automatic recognition of an objects structure and forming the matrix operators taking part in the mode bases search, or in the calculation of step junction S-matrixes. The new code has been tested by the relatively simple objects considered earlier, and by new objects that were not previously considered for MMT modelling because of the laboriousness of an algorithm elaboration. It was shown that the new MMT electromagnetic solver was also applicable in the cases of smooth boundary objects at step-wise approximated surfaces.

Nonsymmetrical H-plane corners for TE/sub 10/-TE/sub q0/-mode conversion in rectangular waveguides

Compact high-efficient TE10-TEq0-mode converters based on truncated H-plane angular junctions of single-mode and overmoded rectangular waveguides are designed and investigated. The comparison analysis of converters without and with an inductive iris in the input port is carried out. Iris-free converters are broader in bandwidth, while iris-matched ones provide a better purity and higher conversion efficiency. It is found that the same configuration can provide a high-efficient conversion to different TEq0 modes in different parts of the frequency operation range. Two interpretations of the conversion physical mechanism are discussed

Electromagnetic modeling of multi-layer microwave circuits by the longitudinal decomposition approach

A system approach based on the transverse-resonance technique and well-equipped modeling system is used to calculate the eigen-mode spectrum of multiconductor lines with piece-wise continuous coordinate boundaries of their cross-section. The exact models of the multi-layer circuits are built with the mode-matching and generalized S-matrix techniques. Viability of the created program tools is demonstrated with the examples of a multi-turn loop inductor and a third-order low-pass filter.

Natural-Frequency Approach to the Synthesis of Narrow-Band Waveguide Absorption Filters

An approach to the synthesis of the waveguide resonator sections filled with a lossy dielectric and absorbing up to 50% of the input power is proposed. The approach is based on the procedure of searching for complex-valued natural frequencies of the resonator sections that provide the required characteristics of a corresponding natural oscillation. Using this approach is promising to design the multi-resonator filters absorbing completely the input power at the desired frequency. The exact numerical results of designing the three-resonator narrow-band absorption filters in the WR-75 rectangular waveguide are presented.

Evanescent-mode bandpass filters based on ridged waveguide sections and inductive strips

A new type of evanescent-mode filter based on ridged waveguide sections is proposed. Insertion of additional inductive strips between ridge sections allows reducing the longitudinal filter size and achieving a sufficient improvement of its stopband characteristics. The features of the developed software and results of its application for filter synthesis and optimization are discussed.