Vol 23, No 1 (2020)

The paper considers mathematical models of metamaterials based on a combination of multi-turned conductive elements, such as helices and gammadions. Analytical expressions are obtained for the resonant frequencies of these elements and relations for material parameters are determined using by the Maxwell Garnett model taking into account the metamaterials dispersion. The propagation constants of circular polarizations waves in these metamaterials are determined. As an example of the constructed mathematical models using, the solution of the problem of reflection of a plane linearly polarized electromagnetic wave from a planar layer of metamaterial, which is a matrix of fine-wire perfectly conducting elements in the form of N mutually orthogonal spirals is considered. The problem was solved by the partial domains method and its solution was reduced to a system of linear algebraic equations for unknown reflection and transmission coefficients of the main and cross-polarized field components. As a result of mathematical modeling, the frequency and polarization-selective properties of investigated metamaterials were revealed.

It is demonstrated, that the problem of synthesis of three-link stepped microwave filter of Butterworth has two symmetric solutions. These solutions have equal wave impedances of the first and last links. The first solution corresponds to filter configuration with low-resistance central link. The second solution corresponds to configuration with high-resistance central link. The expressions for wave impedances of filter links are derived. The results of computation of wave impedances are brought.

The problem of measuring the effective scattering surface (radar cross section) by systems with a synthesized antenna aperture is considered. Using the methods of the statistical theory of detection and spatio-temporal signal processing, the regularities of the formation of the signal component of the optimal filter characterizing the magnitude of the RCS of the measured object are established. The results of mathematical modeling are consistent with the obtained laws.

Bistable MIS structures are promising for use in permanent memory devices, and are a convenient object for studying degradation phenomena under the influence of various external factors. This paper has studied the degradation of I-V and C-V characteristics of bistable germanium and silicon MIS structures with samarium and cerium fluoride under the influence of high electric fields and elevated temperatures. It has been found that empirical dependence of current density on voltage in high-ohmic state is described by degree dependence with index of degree 0,9–1,5. This indicator increases both with the increase in the number of electroforming cycles and with the increase in temperature. On n-type germanium substrates, a positive charge was observed at room temperature for all structures studied. On n- and p-type silicon substrates, the charge can be both positive and negative. Separate exposure to temperature results in an increase in positive charge with an increase in the number of cycles, for both germanium and silicon structures. The separate effect of the high electric field on the MIS structure with the n-type substrate also leads to an increase in the positive charge. However, the complex effects of high electric field and temperature lead to a trend of negative charge growth in the studied MIS structures.

An algorithm for constructing a new class of solutions to spatially one-dimensional problems in the theory of electromagnetic radiation drying has been developed. Its basis is the procedure for splitting the process by physical factors. In the framework of the proposed algorithm, the initial boundary value problems for the heat and moisture propagation equations are solved sequentially using the Fourier method using the Greene function apparatus on successive layers of the difference grid separated by small time intervals. The dependencies of the temperature and moisture content fields on time in such solutions are determined by the eigenvalues of the Sturm-Liouville problem, and the distributions of these fields in space are determined by the eigenfunctions of this problem. A comparison of the new calculation algorithm with known grid methods is made, and new possibilities for analysis that are opened in the drying theory due to this algorithm are indicated.

The article is devoted to the issue of measuring the angular resolution characteristics and the modulation transmission function of panoramic video cameras, which determine the information content of the entire television system. A technique for assessing the potential capabilities of panoramic TV cameras in terms of object detection and recognition is considered. The found characteristics make it possible to calculate the permissible distance to the objects of interest if the linear dimensions of these objects are known.

The analysis of the types of incoming signal switches was performed. The choice of constructive realization of the switch was made. It was offered the method of its designing and simulation. NI AWR Design Environment software was used to implement the method. The model of microwave filter based on microstrip elements was constructed. The scattering and standing wave factors were compared in the voltage of the obtained model and the filter topology. It was determined that the switch provides working capacity both with continuous and impulse radio signals with any kind of modulation. It has a transmission coefficient of radio signals in the operating frequency range in the open state of the inputs without attenuation from 0 to +10 dB, at maximum attenuation – from –28 to –4 dB, and in the closed state of the inputs with the maximum attenuation – from –80 to –100 dB. The level of isolation between the inputs is not less than –50…–55 dB. The transmission coefficient of radio signals from the inputs to the output is regulated in increments of 0,5 dB, with depth of at least minus 15 dB, with the transition tuning less than 100 ns. Switch of coming signals provides a linear operation with the noise level and spurious component at the outputs no more than –90 dB/W and the signal/noise ratio of at least 10 dB in linear mode of operation. The irregularity of the transmission coefficients of radio signals on each of the outputs in the operating frequency range when the inputs are open without attenuation and the linear mode of operation is not more than ±1,0 dB. The second and third order intermodulation distortion coefficient does not exceed –60 dBs when two nanoseconds of radio signals are applied to the inputs.