Nataliya Don

Eigenoscillations of plane junctions and total transmission through small holes

Regimes of resonance transmission through a small below-cutoff hole in a metallic waveguide iris are studied. The resonances are caused by the excitations of specific eigenoscillations of the iris as an open waveguide cavity. Such eigenoscillations are found for irises in various waveguides. Common origin of the eigenoscillations that is peculiar to a plane junction of the hollow waveguides is studied.

Numerical Simulation of Frequency Selective Surfaces Perforated with Arbitrarily Shaped Apertures

We have proposed a method for the electromagnetic analysis of FSS perforated with arbitrary shaped apertures. It is based on the boundary integral equation method, mode matching technique and S- matrix method and has been implemented in a computer code. The data calculated by the code is in accordance with published ones. Furthermore, we have shown the influence of possible fabrication inaccuracies on transmission properties of the FSS.

Multi-slot iris in circular waveguide

Mathematical approach, allowing calculating the basis of electromagnetic unhomogeneities of arbitrary cross section, is applied to solving the scattering problem for multi-slot iris in circular waveguide. Control of the coupling between the waveguide and the iris via a changing the iris profile is shown. Multi-slot iris with not equal slots forming rejection response is proposed.

Mode basis computation for the waveguides of arbitrary cross-section

A method for the computation of cutoffs wave numbers and the natural mode field functions for hollow uniform waveguides of arbitrary cross-section is presented. The core of this method is solution of boundary integral equations of the potential theory and a special parametrization of the contour bounding the cross section. This method is applicable to the waveguides, whose cross-section boundary curvature is either a smooth function or a function having discontinuities of the first kind.

Frequency selective surfaces with L-shaped apertures

Scattering of a plane wave by frequency selective surfaces perforated with one or several L-shaped apertures are proposed. Depending on the surfaces layouts they can lead to the transmission or hybrid response. Features and advantages providing by the L-shaped apertures are discussed.

The Properties of Waveguides and Waveguide Discontinuities Depending on the Azimuthal Symmetry

This paper deals with the waveguides and waveguide discontinuities that have the azimuthal symmetry. The possible mode classes and their degeneracy, and the properties of the S-matrices of discontinuities are presented here. The application of symmetry analysis is illustrated by considering a square waveguide and a thin multi-slot iris in a circular waveguide

Sharp step bended bar in a waveguide as a two-aperture iris

The problem of the dominant TE10 mode diffraction by a thin sharp step bended metallic bar placed in a rectangular waveguide is considered. It is shown that unlike a straight bar such a bar provides the resonance of complete reflection of the TE10 mode in the single-mode band of frequencies. Influence of the bar geometrical dimensions on the frequency and Q factor of resonances is studied. The geometries providing resonances with the high Q factor were found.

Enhanced transmission phenomenon from the eigenoscillation point of view

Eigenoscillations of corresponding waveguide and periodic open resonators have been studied for explanation of the enhanced transmission through irregularities with below-cutoff holes. It has been found that the origin of the discovered effects is in the existence of the eigenoscillations of the interface between the free halfspace and the metal halfspace perforated with double-periodic set of channels or the eigenoscillations of waveguide plane junction.

Full-Wave Analysis of Waveguides Periodically Loaded with Irises

In this paper we have proposed a full-wave approach for the dispersion analysis of waveguides periodically loaded with arbitrary shaped irises. It is based on the boundary integral equation method, mode matching technique and S-matrix method and has been implemented in a computer code. The data calculated by the code are in accordance with published data.

Computation of mode bases for waveguides with complicated cross-sections

At the present time the mode-matching technique (MMT) is one of the most popular and effective methods of waveguide discontinuities analysis and synthesis. With this method, an initial waveguide structure is separated into a set of regular subregions, whose mode bases (cutoff frequencies, natural mode field functions, and mode norms) are known or can be calculated. The MMT is applied to analyse both waveguide mode bases and plane junctions. However the MMT has limited flexibility. If the waveguide has not a separable cross-section its basis calculation is impossible directly with MMT. Methods of calculating the waveguides of complicated cross-section are necessary here, for example, the finite difference method, the finite elements method, integral equation methods and others. Hence a combination of these methods and MMT provides a way of designing waveguide discontinuities with arbitrary shape elements. In the work being presented a new method of mode bases calculation for the waveguides of complicated cross-sections is proposed.