卷 69, 编号 9 (2024)

Planar dual layer and dual mode mirror is considered. The mirror provides simultaneously reflection and transition from one layer to another for two orthogonal modes. The mirror is investigated by electromagnetic simulation in HFSS system. The investigated variants of mirrors provide dual mode matching at –(20…34) dB level in frequency range 2.5:1 and in the range of angles of incidence ± 60°. Application of dual mode mirrors for dual polarized narrow beam planar antennas design is discussed.

Numerical simulation of electromagnetic fields in a waveguide plasma torch has been carried out, in which microwave plasma heating is carried out by continuous radiation from a technological gyrotron with a frequency of 24 GHz and a power of up to 5 kW. It is shown that a decrease in the output diameter of the plasma torch makes it possible to more than double the amplitude of the electric field, but when the diameter decreases to 8 mm, the reflection coefficient increases significantly, which leads to reflected radiation entering the gyrotron. It is shown that taking into account the collision frequency corresponding to the real parameters of the atmospheric pressure discharge leads to a decrease in the reflection coefficient by more than 10. It has been experimentally confirmed that with a decrease in the output diameter of the plasma torch, the range of discharge maintenance parameters significantly expands, and the absorption coefficient exceeds 80%.

The problem of the influence of a noise interference coming from the side lobe of the antenna on the depth of a noise polarization suppression of interference in the main beam is considered. The problem of interference effect is considered for a passive phased antenna array with switchable polarization of antenna elements. An estimate of the depth of polarization suppression has been obtained.

Flat-top windows intended to reduce spectrum amplitude measurement error in discrete harmonic analysis are considered. A new family of flat-top windows, which provide the minimum level of the highest spectrum sidelobe and low calculation complexity is proposed. Mathematical representation of the new windows and a method of optimization of their parameters, which rely on authors’ earlier works are described. A number of flat-top windows of orders 1…6 and sidelobe falloff rates of 6, 12, 18, 24, 30, 36, and 48 decibels per octave are synthesized, tables of their parameters are provided, and their characteristics are analyzed. An alternative technique to reduce the spectrum amplitude measurement error is proposed.

A description of the algorithm for optimal symbol-by-symbol reception of signal structures based on correction coding in non-binary Galois fields is given. The results of modeling this algorithm are given in order to study its noise-immunity for transionospheric channels with fading due to scattering on ionospheric irregularities for a number of digital signals with multi-level phase shift keying in combination with a correction code with a parity check in Galois fields. It is shown that for these channels the use of a symbol-by-symbol reception algorithm provides an energy gain of up to 4.5...24 dB in relation to the reception of signals without coding.

The conditions for the existence of certain homogeneous and inhomogeneous optomagnetic effects due to light-induced changes in the ground state have been determined for the actually existing magnetic ordered single crystals with different magnetic symmetry.

Numerical modeling of the anomalous Hall effect in thin-film structures with strong perpendicular magnetic anisotropy was performed. The dependence of the Hall response on the position of a single domain inside the measuring cell (the Hall cross) was found. Corrections associated with the imperfection of the structure — rounded corners of the cross — were determined. The contribution to the Hall response of the skyrmion caused by the anomalous Hall effect was calculated.

The algorithms and results of calculations for electron beams from magnetically shielded cathode in ρ - mode emission are discussed using the second approximation of geometrized theory.