Compact polarization rotators based on the diaphragms with several rectangular apertures

A possibility to design a compact polarization rotator based on the structures of dihedral symmetry is studied. Here, the diaphragms with several equal rectangular apertures are considered as dihedral symmetry structures. Ultimate performances of the rotators considered are obtained by using different optimization procedures. They demonstrate acceptable reflection in the predetermined frequency band. The rotators that achieve the polarization plane rotation by an angle of choice are examined as well

Novel approaches to the analysis and model synthesis of ultra-wide-band horn-type antennas

Model problems in the theory of ultra-wide-band horn-type antennas are initial boundary value problems in infinite domains with locally inhomogeneous and perfectly conducting compact scattering objects. The key to their efficient solution lies in the correct truncation of a computational domain, which on the one hand, reduces the fundamentally open problem to the closed one, and on the other hand, has little or no effect on the accuracy and reliability of resulting numerical data

Enhanced transmission through below-cutoff holes and eigenoscillations of waveguide objects and periodical structures

The spectral theory is used to explain the enhanced transmission phenomenon. Eigenoscillations of corresponding waveguide and periodic open resonators have been studied. Their influence on frequency response is demonstrated for various structures. It has been found that the origin of this recently discovered effect is in the existence of the eigenoscillations of the interface between the free half-space and the metal half-space perforated with double-periodic set of channels or the eigenoscillations of the waveguide plane junction

Electrodynamic model of the three-band feed for VLBI2010 radiotelescope reflector

An exact full-wave model for a design of multi band horns based on the hybrid mode matching and Winner-Hopf method is described. The model is well suited for optimization owing to the mode-matching approach. The complex horn structure is constructed from a set of fundamental building blocks, and the scattering matrix of the entire device is found by cascading of the scattering matrices of the individual components. The main steps of the realization for a three-band (S/X/Ka) feed horn compatible with VLBI2010 standards are considered

Abnormal propagation of EMW through below cutoff holes and intrinsic oscillations of waveguide objects and periodic structures

Spectral theory is used to explain the effect of propagation through below cutoff holes. Intrinsic oscillations of the corresponding waveguide and periodic open resonators are studied. Their influence on the frequency characteristic is demonstrated for various structures: from waveguide to array

Recent advances in computational electromagnetics for microwaves in IRE NASU

Recent advances in problem-oriented and generalpurpose microwave-oriented software and applications developed in the department of computational electromagnetics are considered. Numerical-analytical automatic mode-matching based models are extended on the objects given in cylindrical coordinate system. The geometry has to be specified as the set of piece-wise coordinate fragments in Cartesian (MWD1 or MWD2 with account of edge behavior) or in Cartesian or cylindrical coordinates (MWD3) with automatic cross-section geometry recognition and subsequent formation of corresponding modematching technique and S-matrix based numerical algorithms. The future extension to the double-periodical screens and multilayer printed circuits (MWD4) is described moving to terahertz frequency band and “metamaterial” investigations. A set of new microwave devices is proposed which are based on the nonstandard physical principles such as the fringing field interaction, new types of eigen-oscillations of 3D open objects and artificial “optical activity”. They are the band-stop and bandpass waveguide filters, antenna-feed units, polarization rotators, twists etc

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