The accurate model of the clinotron slow-wave structure is built on the basis of mode matching technique. The influence of the distance between the lamellar grating and the waveguide side wall is investigated

An attempt of combining the efficiency of problem-oriented numerical algorithms with the generality of mesh methods is made. The automatic procedure of decomposition of complicated waveguide structures is developed. It takes into account peculiarities of the given problem (symmetries, uniformity and so on) and tries to find out the best possible solution. Presented approach is successfully applied to create the electromagnetic simulator Microwave Desktop 2 (MWD 2). It allows one to solve a wide range of electromagnetic problems from analysis to optimization.

Radio equipment miniaturization requires reducing the dimensions of waveguide transmission lines. Lowering the frequencies enforces using the waveguides of more complicated cross-sections. Some results of the analysis of complicated waveguides are presented in the report. Some new designs of such a type waveguide have been proposed. For the waveguides, matrix operator based on MMT has been generated. It allowed to calculate their waveguide bases with required accuracy quickly.

se, =iA(I -R-T) /ZAT; pel =iA( I+R-T) /2AT , (1) whereR and Ta re the amplitudes of reflected and transmitted waves found from the rigorous solution. These formulas are valid in the frequency range where only one space harmonic is propagating in the domains I and Il. It has been proved numerically, that within the frequency band d//l < 0.5 the structure Fig. la has constitutive parameters with Re(&) < 0. see Fig. 2,a.. It is clear that one can control the effective values Ee/ and pe/ by changing parameters /l , d, h , R and T .

This paper presents a method of calculation of cutoff wave numbers and natural mode field functions in waveguides of rectangular cross section with rounded corners. The method is based on a solution of boundary integral equations of the potential theory. A special parametrization of the contour bounding the waveguide cross section is proposed.

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.

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.

A new design of capacitively coupled bandpass filters, that provides suppression of spurious passbands for the dominant and second waveguide modes without any extension of the filter dimensions, keeping the same return loss within the passband, is presented. Spurious passband suppression is provided by cutting an additional pair of slots into the iris strips . Cutting the additional slots leads to the appearance of attenuation poles, which are placed in the spurious passbands. The k-inverter of the corresponding two-side double-slot iris changes slightly and may be easily fine-tuned. Numerical examples are presented for the three-section 5% filter in a WR90 waveguide.

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.

Some configurations of E-tee diplexers are synthesized and analyzed for the case of closely spaced channel frequency bands in the upper part of a rectangular waveguide operating range. The results of rigorous electromagnetic synthesis and analysis of the millimeter-wave diplexers with all-metal E-plane insert channel filters are presented.

The paper presents the internal details of a developed full‐wave algorithm for the computer‐aided design of evanescent‐mode bandpass filters formed by single‐ or double‐short ridged waveguide sections. New filter configurations with an enlarged cross section of filter housing and nonconventional notch‐strip‐notch elements providing improved stopband performance are given special considerations. Additional input–output transformers built on rectangular waveguide sections are used in designing broadband filters. Characteristics of one of the designed filters are verified by measured data. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 354–365, 2001

The main goal of realized project was to suggest a new generalized approach to mode-matching procedures both for calculation of sophisticated WG mode spectra and for calculation of the frequency response of complicated devices as well. Moreover, we have attempted to create fully automated algorithms that, permit one to avoid the stage of analytical consideration, i.e. to get rid of individual approach to each of the new configurations produced by practice. Together with special tools for recognizing the contours of WG cross-sections and their preliminary processing they provide the background for hookup to "mode-matching" solver - the comfortable interface for "geometrical specifying and editing". The classes of the objects that may be calculated by suggested approach include any WG devices with metal boundaries specified in Cartesian coordinate system or with the smooth boundaries that may be replaced by stair-case surface

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.

Orthomode transducer (OMT) aiming to divide the signals of orthogonal polarizations, is an important part of antenna circuits of modern communication systems. One of the most popular solutions to separate two linear cross-polarized signals is based on the tee in the square waveguide. The design of such a device is hampered by a lack of efficient mode-matching solution for the main key-element. Therefore it is required to use very time-consuming numerical algorithms based on one or another kinds of lattice methods. The goal of this report is to extend the area of mode-matching applications on the tees with inserts in tee interiors by the example of key-elements of OMT. New mode matching based algorithm for S-matrix calculation provides very high accuracy at low CPU time and enables the possibility of quick optimization of the OMT geometry as a whole.

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.

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.

Some aspects of designing lowpass and bandpass evanescent-mode filters based on single-and double-ridge waveguides are discussed. It is demonstrated that an introduction of the new type of transformers allows to obtain the lowpass filter configurations providing wide pass and stop bands. The improved procedure of initial synthesis of bandpass filters permits to obtain their geometry for pass bands up to 20% and extended stop band.

A new procedure for compact diplexer design is proposed. It consists of the integration of a dividing unit and the first K-invertors of channel filters and is based on an exact calculation of S-matrices of the combined waveguide units. As a result essential reduction of diplexer length without a degradation of frequency response has been obtained

There are two approaches to the problem of frequency selective device synthesis: the traditional one based on circuit theory, using the numerical solutions of boundary value problems only at the stage of the reconstruction of filter element geometry according to the requirements on its single-mode S-matrix; and a relatively new method based on methods of numerical optimization. However, there are some specific procedures that generate an intermediate way combining the wide intellectual basis of the first approach and the high accuracy of the second. The authors discuss such a technique for the design of waveguide band-pass filters