Journal of Communications Technology and Electronics

The numerical modeling of the frequency characteristics of the Sestroretskii cube is performed. It is shown that the interior Sestroretskii cube exhibits the properties of a double waveguide T-branch. The hypothesis that signals propagate inside the Sestroretskii cube with the velocity that is the double light speed in vacuum is justified. The limitations of the spectrum of these signals are formulated.

Two-dimensional self-consistent simulation is used to study collisionless mechanisms for dissipation of energy of the HF field in an inductive discharge developing in the presence of a magnetic field with a neutral loop. The regimes in which the local electron-cyclotron resonance plays the main role in the heating of plasma electrons are demonstrated. The results of numerical simulation are in agreement with published experimental data, thereby making it possible to qualitatively interpret the latter.

Issues related to the attenuation and scattering of radio waves by rainfalls and snowfalls at frequencies higher than 30 GHz are considered as applied to the meteorological -radar operation. Certain of its parameters are estimated.

This paper, energy detection using a bootstrap approach describe a proposal for spectrum sensing. The proposed model is applied in the case of small sample size and to deal with the problem of correlated test statistics to estimate a test statistic distribution. This new approach requires no prior information about the background environment and uses a bootstrap method for resampling to approximately maintain the time dependencies that distinguish the presence and absence of the signal. For the previous cases, the estimation of the distribution can be performed through two ways, parametric and nonparametric bootstrap. Firstly, we display the approximation of the distributions of the test statistic, which a fully nonparametric hypothesis testing is proposed, using bootstrap approach. Accordingly, the distribution of the test statistic can be approximated employing the empirical distribution proceeded by bootstrapping. The second way, we employ a bootstrap founded approach to approximate unknown parameters which describe the distributions of the test statistic in correlated Gaussian case, using moving blocks bootstrap to generate performing independent resampling. The proposed detector exploits the sample covariance matrix to form an estimation of a distribution of the test statistic. Through simulations, the performance of the proposed detector is analyzed and compared with conventional energy detectors (CED) on the small sample size. The obtained results reveal that our proposed method outperforms greatly even with sample of small size, which is known usually the deadlock of detection performance in conventional and classical spectrum sensing and offers a robust detection performance to enhance the detection process in case of noise uncertainty environments.

Modes of a planar dielectric waveguide are investigated. The waveguide is made from a nonlinear metamaterial with a negative permittivity and a negative permeability. The mode wavenumbers and field distributions are calculated for structures with parabolic permittivity and permeability profiles. It is shown that anomalously high field intensities can be observed in such a structure. The dependences of the mode propagation coefficients on the electric field are analyzed for the case of nonlinear media. The effect of nonlinearity saturation is considered.

New band-passing frequency-selective surfaces (FSSs) are proposed and investigated. Formulas for calculating the modulus and phase of the reflection coefficient of artificial magnetic conductors are obtained based on the proposed FSSs. The comparison of the results of electrodynamic modeling and calculation by formulas is carried out. The possibility of expanding the operating frequency band is shown.

Abstract—The purpose of this article is to analyze the capacity of a discrete-continuous communication channel (DC-channel) as applied to nonorthogonal multiple access (NOMA) systems. In this work, an expression is obtained for the individual mutual information of a DC-channel in communication systems with nonorthogonal access, which makes it possible to analyze the capacity of the DC-channel individually for subscribers of NOMA systems. Its effectiveness for analyzing group signals of NOMA systems is shown, examples of its use are given, and capacity characteristics for NOMA subscribers are obtained as well.

Systems of van der Pol generators with capacitive and resistive coupling are considered. New mathematical models that allow excitation of chaotic oscillations by means of the algorithm of parametric chaotization in systems containing two generators are presented. Results of numerical analysis of chaotic operation modes are presented. Modification of chaotic effects in a coupled system is studied for the cases when coupling is asymmetric and a delay is introduced into the parametric-chaotization algorithm.