Vol 68, No 9 (2023)

A slowing medium based on parallel corrugated metal surfaces. The study of the moderating properties of the medium was carried out using numerical method in the Ansys HFSS software environment. It is shown that the medium has a strong spatial natural and weak frequency dispersion. The latter circumstance allows it to be used in as a material for broadband lenses of the VHF-microwave ranges of electromagnetic waves. As an example of such use, a lens-based antenna was synthesized and analyzed Mikaelyan.

Superconducting integrated circuits based on NbTiN/Al transmission lines at frequencies up to 1.1 THz have been developed and experimentally studied. Numerical modeling of two microcircuit topologies with an operating frequency range of 0.9…1.2 THz, containing a slot antenna, made in a thin NbTiN film and matched in output to a microstrip transmission line, and a tunnel junction of the “superconductor–insulator–superconductor” (SIS) type with an area of the order of 1 μm^2, acting as a terahertz detector. Experimental samples of the microcircuit were manufactured and tested; in the experimental setup, a backward wave lamp (BWL) with an output frequency of up to 1.1 THz was used as a source. A powerful pumping of the SIS detector was obtained, thereby demonstrating the applicability of the manufactured NbTiN/Al transmission lines for operation in superconducting circuits at frequencies above 750 GHz, where traditionally used Nb/Nb transmission lines do not operate due to high attenuation.

A description of the algorithm for optimal symbol-by-symbol reception of signal structures based on block noise-resistant codes in non-binary Galois fields is given. It is shown that the basis of this algorithm is the fast spectral transformation algorithm in the Walsh–Hadamard basis with the dimension of the Galois field. It is shown that the resulting complexity of the analyzed character-by-character reception algorithm is determined by the dimension of the dual code, which determines the prospects of its application for block noise-resistant codes with a high code rate (with low redundancy). The results of modeling a character-by-symbol reception algorithm are presented in order to study noise immunity for a number of frequency-efficient digital signals with quadrature-amplitude and amplitude-phase manipulations (with frequency coefficient efficiencies of 3, 4 and 6 bps/Hz) in combination with a parity check code. It is shown that the use of a symbol-by-symbol reception algorithm provides an energy gain of up to 1.5...3.0 dB in relation to the transmission and reception of the considered series of signals without coding.

Without using the magnetostatic approximation, the problem of the propagation of electrical magnetic waves in an arbitrary direction in a tangentially magnetized one-sided metal sized bigyrotropic layer. It is shown that in this problem Maxwell’s equations reduce to differential equation to which the biquadratic characteristic equation corresponds equation with four roots k_x21, –k_x21, k_x22 and –k_x22, describing the distribution of the wave in the cross section layer. A dispersion equation is obtained that describes waves with real values k_x21 and k_x22. Based on this equation, the characteristics of spin waves in a one-sided metallized ferrite plate (which is a special case of a bigyrotropic layer) were calculated for frequencies above the ferromagnetic resonance frequency. It was found that for these waves the quantity k_x21 can take both real and imaginary values, and the quantity k_x22 can only take real values. It was discovered that at a certain frequency the spin wave has an isofrequency curve that is practically no different from a straight line.

Modeling of superconducting integrated structures in the frequency range was carried out 300...750 GHz by two methods: 1) using ABCD matrices associated with each element of the circuit;  2) using the Ansys HFSS program. The surface impedance values of superconducting films are calculated numerically using expressions from the Matthies–Bardeen theory. It was found that for samples with microstrip line widths less than a quarter of the wavelength, both models are in qualitative agreement with each other and with experimental data. Shown that with an increase in the width of the lines and the geometric dimensions of other structural elements, transverse modes arise, as well as curvature of the wave front propagating along the lines waves, which causes differences between the semi-analytical and numerical calculations, which coincide with the experiment for all samples.

 The features of the technology of experiments on the non-thermal effects of high-power nanosecond pulses are considered using the example of a setup used to modify biological media and other objects with heterogeneous electrophysical characteristics. An experimental setup has been created to study the non-thermal effects of high-power pulses on samples of various materials, which generates pulses with a repetition frequency of up to 500 Hz, amplitude up to 60 kV and duration 5 ns. Simulation of transient processes in the equivalent electrical circuit of the load was carried out, and a biological one was used as a load material placed in a microplate.

A technique has been proposed for obtaining films of barium hexaferrite on sapphire with the (0001) orientation using the high-frequency magnetron sputtering of a stoichiometric BaFe12O19 target followed by annealing The performed X-ray diffraction analysis and Raman spectrometry showed the possibility the possibility of crystallization of oriented films without using correction of the target composition.

A method for receiving ultra-wideband noise-like microwave radiation -- radio light is considered, based on the correlation reception of signals coming from spaced apart space of receiving antennas, for the purpose of further effective image formation radio-illuminated environment. A mathematical model has been developed to study the formation possible response of the receiving system and assessing the influence of signal accumulation time on its dynamic
range. One-dimensional responses of the correlation receiving system to point sources of radiation were obtained, for which radio light sources were used. An experimental model of a correlation radio light receiver was developed and physical experiments were carried out with it, confirming the results obtained during modeling, as well as the overall performance of the proposed approach.