V.I. Tkachenko

Semi‐inversion method for an accurate analysis of rectangular waveguide H plane angular discontinuities

The new efficient numerical-analytical method of electromagnetic interior boundary value problem solving is presented with waveguide H plane angled bends as examples of implementation. The method essence consists in the analytical inversion of the main difference part of the initially derived ill-posed matrix equation of the first kind. As a result, the problem is reduced to the solution of the second-kind matrix equation with an invertible operator. The proposed method differs from other methods dealing with so-called modified Wiener-Hopf geometry structures. It is oriented to noncoordinate boundary value problems to which the ones of angular waveguide discontinuities are related. Detailed consideration of all parts of the numerical algorithm ensures its high efficiency. As application examples, the data for designing the matched truncated corners in a single-mode waveguide and the results of comparison of the known high-frequency heuristic estimations with the exact simulation of waveguide corners having a quasi-optical mirror are presented.

Stepped approximation technique in the problem on polarizer based on circular waveguide with rectangular ridges

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.

Orthomode transducers with a common circular waveguide

An efficient electrodynamic model and an optimization procedure for orthomode transducers based on a circular waveguide and step transitions in rectangular input arms is developed. The physical factors limiting the operating bandwidths of these transducers are determined. The effect of the number of sections in the step transitions on the characteristics of single-band transducers are investigated.

Analysis of the Clinotron Slow-Wave Structure

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

Exact model of radiation from an open-ended cylindrical waveguide with corrugated flange

The solution is based on a combination of Wiener-Hopf method for the external waveguide section and the MM method for the intemal one. The analysis is subdivided in three calculation steps. The first step in this approach is to decompose the inner part of the waveguide into a certain number of cells based on the common module depicted in fig. 2. This module consists of the abrupt junction of two circular waveguides of different diameters, the junction being reactively loaded by a short-circuited coaxial waveguide. The coaxial stub directly represents the single slot cut into the wall and waveguide sections can be approximated by connecting several modules in series. The fields are derived from the z-components of the electric and magnetic vector potentials P, and Ph in the form

Organization of “electrodynamic assemblage” in calculation of complex waveguide objects

The main principles of constructing the algorithms for calculation of antenna-feeder objects of complex composition by means of the S-matrix method are presented. Consideration for all types of symmetry, from the symmetry of the cross section of the transmission line to the symmetry of the entire unit in the longitudinal or transverse direction, and application of special “electrodynamic-assemblage” diagrams whose structure depends on the presence of variable or invariable key elements and sections of transmission lines can minimize the computation time. This approach is of particular importance in solving multiparametric optimization problems, where an appropriate choice of the assemblage diagram may reduce the computation time by several orders of magnitude. The diagram described is tested on various units, from filters and multiplexers to dividers and polarization changers.

Electromagnetic simulation and design of dual-band ortho-mode transducers

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.

Comparative analysis of an open-ended waveguide antenna pattern obtained by exact model and by heuristic approaches

An open-ended waveguide as a front-end radiating component is a wide-spread element of many antenna systems. Though the problem of its radiation pattern calculation is an old one, however, some aspects are not completely developed. One of the most popular method for calculation of radiation characteristics is the Kirchhoff-Huygens approximation. This paper attempts to verify the field of application of the Kirchhoff-Huygens method and develop a surrogate model for intensive calculations. Results indicate that one can use the Kirchhoff-Huygens method for calculation of power patterns as well as polarization and cross-polarization ones with sufficient accuracy for practice purposes. Otherwise, it is possible to apply this approach for calculation of power characteristics in the main lobe direction, while polarization and cross-polarization patterns are still sensitive to error of the approximation model.

Wave scattering from periodic multilayer structures

The computation of single gratings lead to the analysis of the whole structure. Multimode interaction between the scatterers dramatically complicates the theoretical model. If the angle between the gratings rulings is not equal to zero then the problem becomes vector one and therefore, two-dimensional Floquet bases in an oblique coordinate system are used. Then, some auxillary algorithms that significantly simplify the computation procedure by reducing the main problem to set of subproblems, which are analyzed in the one dimensional basis, are considered. The common concepts of such an approach are presented by an example of two-layer grating array.

Compact septum polarizers with a circular output waveguide

Septum polarizers (SPs), built on a square waveguide with stepped ridged waveguide junctions, have found many applications in antenna systems and polarization measurement equipments. In the present paper, the features of the developed CAD of compact square-waveguide SPs with a circular output waveguide and results of its design application are discussed. The SP configurations under consideration are combined by the following components: rectangular-to-rectangular, bifurcated square-to-ridged, ridged-to-ridged, square-to-square, and square-to-circular waveguide junctions. Exact numerical models for all the components are built on the mode-matching technique. The eigen-value problem for the single-ridged waveguide is solved using the moment method with basis and tested functions taking into account the field behavior near edges.