A. A. Kirilenko

The Simplest Notch and Bandstop Filters Based on the Slotted Strips

New configuration of the notch and bandstop filters is proposed and investigated. Here a rejection section is based on a thin slotted H-plane strip that may be considered as a limiting case of a three-slot iris. Such a section forms symmetrical frequency response with very low insertion loss out of the stopband. The results of numerical design and measurement data are given for a 3% notch filter and for 2% three-section bandstop one. In the low-power applications the proposed notch filter is probably the simplest one due to its easy fabrication and a possibility to be incorporated into a waveguide circuit by placing between the waveguide flanges.

Ultra-compact 90° twist based on a pair of two closely placed flat chiral irises

A new ultra-compact device for rotating the polarization plane of planar electromagnetic wave in a square waveguide by 90° whose dimension is almost ten times less than wavelength is suggested. It is based on strong interaction of near-fields in two closely placed flat chiral irises. It is shown that this approach due to strong multi-mode and near-field interaction allows rotating the polarization plane by 90° in the several percent bandwidth with the loss level not worse than 0.1 dB.

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.

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.

Natural oscillations providing 90° polarization plane rotation by planar chiral double-slot irises

The common origin of the “enhanced transmission” through small holes and polarization plane rotation (“optical activity”) resonances peculiar for a pair of conjugated planar chiral irises is demonstrated. The eigenoscillation spectra are studied extensively from the “aperture” eigenoscillations of plane junctions responsible for the “enhanced transmission” through the planar chiral iris up to the eigenoscillations of “dihedral” symmetry formed in a composite double slot planar chiral iris. Their excitation results in polarization plane rotation of the dominant mode in a square waveguide. A new compact unit for TE01 to TE10 conversion operating within 5–10% frequency band is proposed and validated experimentally. All conclusions are valid for various types of metasurfaces based on the “fish-net” gratings.

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

Numerical determination of eigenmodes of an arbitrary waveguide with coordinate boundaries in cylindrical coordinate system

Waveguide units with coordinate boundaries in the cylindrical coordinate system are widely used in microwave devices based on circular and coaxial waveguides. Besides the universal finite element methods more accurate and efficient algorithms were built for the analysis waveguides of this kind. However, all of the currently available algorithms were developed for the analysis of individual structures of interest, mainly for ridge waveguides. So far the general algorithm suitable for the analysis of any waveguide of this class has not been developed yet. In this paper we eliminate this gap by a generalization of the mode matching technique to the waveguides with coordinate boundaries in the cylindrical coordinate system taking into account field singularities. The final goal was to obtain a tool for fast calculation of the mode spectrum (up to hundreds) as it was previously built for the waveguides with piesewise Cartesian coordinate boundaries.

Eigen-oscillations of composite double-slot iris in a square waveguide and manifestation of enhanced transmission and “optical activity”

The widespread implementation of the powerful hardware and grid computing software in computational electromagnetics has spawned a wave of the publications devoted to the analysis of the complex three-dimensional structures, generating innovative applications. As an example, the analysis of a variety of objects, providing a giant “optical activity” (rotation of the polarization plane) due to topology complication can be cited [1].

Circular polarization splitters for three-band feed of radiotelescope reflector antenna

The results of the design and testing of circular polarization splitters (polarizers) of the Ka-, X-, and S-bands, intended for operation as constituent parts of a three-band feed of a radio telescope reflector antenna, are presented. In addition, the results of developing a set of polarizers intended for connecting to waveguide outputs of band-measuring horn antennas are presented. These polarizers are developed to measure the antenna feed patterns on the co- and cross circular polarizations.