# Vol 22, No 3 (2019)

**Year:**2019**Articles:**10**URL:**https://journals.ssau.ru/pwp/issue/view/405

## Articles

### Determination of the spectra of solutions of boundary value problems for guiding structures using the transition to integral equations

#### Abstract

The vast majority of guiding structures are described [1–3] by non-self-adjoint electrodynamic operators, which are understood as the totality of the differential equation and the system of boundary conditions. In [1–5], the conditions for the non-self-adjointness of electrodynamic operators are formulated as applied to the method of separation of variables. The indicated operators can be put in accordance with [5–6] integral equations. The boundary problems for cylindrical guiding structures are assigned the Volterra integral equations, using asymptotic solutions of which an a priori determination of the spectra of solutions of boundary-value problems for two-layer open and shielded waveguides is carried out.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):5-9

### All-arround looking antenna based on linear expanding symmetric slot lines

#### Abstract

Properties of the all-arround looking antenna executed on a basis of radiators in the form of linearly expanding slot lines placed on two coaxially located disks displaced azimuthal on a corner are described. The antenna works in the frequency range of (8–12) GHz, is intended for forming of the directional radiation providing the circular or sector scan.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):10-14

### An aperture’s amplitude-phase distribution for forming frequency-independent direction-finding characteristics of a linear antenna arrays

#### Abstract

The aperture’s amplitude-phase distribution of a linear antenna array, ensuring the formation of frequency-independent direction-finding characteristics in a wide frequency band, is considered. The basic regularities of the choice of the amplitude-phase distribution parameters of linear antenna arrays for the case of frequency independent amplitude distribution and frequency dependent phase distribution are investigated. Using the example of a 45-element linear array designed for operation in a frequency band with a relative overlap of 4:1, the influence of the amplitude and phase distribution’s parameters on the magnitude and deviation’s character of the direction-finding characteristics in the operating frequency band is investigated. It is shown that the introduction of a substantially decreasing amplitude distribution contributes to a decrease in the integral standard deviation of the direction-finding characteristics in the frequency band. The relationship between deviation of frequency dependence of the direction-finding characteristics of the array and variations in the frequency dependence of the phase distribution in the aperture is established. The analysis of the basic regularities of the formation of frequency-independent direction-finding characteristics of broadband antenna arrays has been carried out.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):15-20

### Influence of solar activity on the phase of the received signal VLF range

#### Abstract

The effect of sunspots in the 21 cycle of solar activity on the phase of the received signal on two paths and different frequencies is considered. Experimental data were obtained from the phase of the signals received by the Omega radio navigation system. Distribution routes pass practically from south to north. It is shown that the influence of sunspots on the phase of the received signal is practically absent. It is necessary to consider other parameters of solar activity.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):21-26

### Application of the Fourier method to solve the problems of the theory of drying by electromagnetic radiation

#### Abstract

On the basis of the idea of splitting the process into physical factors, using the Fourier method and the green function apparatus, an algorithm for constructing a new class of solutions to the initial boundary value problems of the theory of drying by electromagnetic radiation is developed. A subclass of asymptotic solutions, which are obtained by the limiting transition and give a description of the established drying processes, is distinguished. The dependences of the temperature and moisture content fields on time in such solutions are determined by the first eigenvalues of the Sturm – Liouville problem, and the distributions of these fields in space are the first eigenfunctions of this problem. The analysis of asymptotic solutions allows us to establish and visualize the basic laws of electromagnetic drying, which can be used for engineering estimates of process parameters and the calculation of temperature and moisture content fields in the first approximation.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):27-35

### The entanglement of atoms with two-photon transitions in the presence of ac Stark shift of energy levels

#### Abstract

In this paper, we investigated the dynamics of atomic entanglement in a quantum system consisting of two identical two-level atoms (qubits) resonantly interacting with a mode of a thermal cavity field through degenerate two-photon transitions, in the presence of a Stark energy level shift. An analytical expression is obtained for the atom entanglement (negativity) parameter for separable and entangled initial states of atoms. The influence of the Stark shift on the degree of atom-atom entanglement is considered. It is established that the Stark shift leads to a significant increase in the degree of atom entanglement in the case of separable initial states of atoms and to stabilization of atomic entanglement in the case of entangled initial states of atoms.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):36-43

### Physically reasonable time sampling in mathematical models of generators of regular and chaotic oscillations

#### Abstract

The issue of transition to discrete time in mathematical models of nonlinear dynamic systems oscillating in continuous time is considered. On the basis of the examples of the Dmitriev – Kislov and van der Pol generators, the approach based on maintaining in the process of time sampling the impulse response of the linear oscillatory circuit included in the generator is described. This «physically reasonable» sampling allows models of non-linear dynamics to be formulated in discrete time, adequately reproducing the characteristics of analog prototypes, which is not always possible with a widely used combination of explicit and implicit Euler methods.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):44-48

### Analysis of a system with exponential and hyper-Erlang distributions by the method of spectral decomposition of the solution the Lindley integral equation

#### Abstract

In this work, we obtain the spectral decomposition of the solution of the Lindley integral equation for a queuing system with a Poisson input flow of requirements and a hyper-Erlang distribution of the service time. Based on it, a calculation formula is derived for the average queue waiting time for this system in a closed form. As you know, all other characteristics of the queuing systems are derived from the average waiting time. The resulting calculation formula complements and extends the well-known Polyachek-Khinchin formula in queuing theory for M/G/1 systems. In the queueing theory, studies of private systems of the M/G/1 type are relevant due to the fact that they are still actively used in the modern theory of teletraffic.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):49-54

### Experimental investigation of semiconductor structures of the power source based on carbon-14

#### Abstract

The article presents the research results of semiconductor silicon carbide (porous) structures with the implanted carbon-14. The results of experimental measurements collected data on parameters of photovoltaic energy conversion of light quanta into a photo-EMF to confirm the efficiency of p-n junction, an evaluation of the effectiveness of the introduction of carbon-14 in the molecule silicon carbide electrophysical measurements. In the process used the technology of solid-phase transformation of the surface of the monocrystalline silicon substrate in the phase of monocrystalline silicon carbide by chemical transport of carbon in the environment of hydrogen.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):55-67

### Porous structures based on silicon carbide for photovoltaic cells

#### Abstract

A method for producing porous silicon carbide by carbonization of porous silicon is considered. The surface morphology and phase composition of porous silicon carbide layers obtained by diffusion of carbon from the gas phase into the porous silicon layer are investigated. Diffusion and absolute reflection spectra of porous silicon carbide and porous silicon samples are obtained. A study of the specific surface resistance and lifetime of excess charge carriers in porous silicon carbide was carried out. Using of porous silicon carbide in photovoltaic cells to increase their efficiency is shown.

**Physics of Wave Processes and Radio Systems**. 2019;22(3):68-74