Vladimir Tkachenko

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.

Waveguide diplexer and multiplexer design

A new computer-aided procedure of designing waveguide manifold multiplexers, which combines a rigorous numerical analysis of electromagnetic characteristics of the key elements of the structure and a simple circuit engineering design technique, is proposed. This procedure enables one to obtain the required multiplexer characteristics without any experimental corrections at the minimum computer time expense. Typical design results are given to demonstrate the efficiency of the method. >

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.

Extracted Pole Bandpass Filters Based On The Slotted Irises

A new design of directly coupled bandpass filter that provides extracted stopband poles is presented by the example of a capacitive iris filter. The attenuation poles are introduced by cutting in iris strips additional slots parallel to the wider waveguide wall. This way of extracted poles implementation does not require spatially developed elements (in particular overmoded ones). The K-inverter corresponding the modified iris changes slightly and may be easily fine-tuned. Additional slot dimensions determine the location and Q-factor of the attenuation poles, which may be placed in the parasitic passband or on a required skirt of the main one. Numerical examples for the three-section filter in WR90 waveguide demonstrate the possibility to increase the skirt selectivity or to improve the stopband attenuation without any extension of the filter dimensions, keeping the same return loss within the passband.

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.

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.

Decomposition approach to multilayer circuits electromagnetic modeling

A system approach based on the transverse resonance technique and a well-equipped modeling system is used to calculate the eigen-mode spectrum of the multiconductor lines with the piecewise coordinate boundary of cross-section. It serves as the background for calculation of the multilayer circuit frequency response by mode-matching and S-matrix techniques.

Integrated software package for synthesis, analysis and optimization of frequency-selective devices of millimeter and centimeter waves

The state of the art of theory and practice of signal frequency selection in the millimeter and centimeter wave ranges can be described from one hand as going to more sophisticated schemes of filter building and from another hand, especially in millimeter waves, by extensive usage of practically non-tuning configurations. The first direction as well as the second one is based on the powerful software and on modern production processes, that provide minimal tolerances. Below is a summary of the results that have been obtained in IRE NASU regarding to one of this two sides of filter problems: the short description of the set of software packages for the synthesis and analysis of low-pass (LPF), wide-band and narrow-band band-pass (BPF), and band-stop (BSF) rejection waveguide filters.