Equivalent circuit of a ferrite-wound inductor in a wide frequency range (0 Hz – 500 MHz)

Based on the measured impedance of the inductors wound on various ferrite cores and with a different number of turns, an equivalent high frequency (0 Hz 500 MHz) circuit model was built. The equivalent circuit model was built taking into account the physical processes occurring in the inductor: effect of wire resistance, effect of core material, mutual effect of wire and core material. The attempt explaining why the frequency characteristics (modulus and phase) of the inductor complex impedance have such a character in a wide frequency band (up to 500 MHz) was made. It was shown that for constructing an equivalent circuit model (structure and parameters), measuring only the inductors resistance modulus is not enough. It is also necessary to measure the phase of the inductor complex resistance, which is ignored in many works on the synthesis of an e inductor equivalent circuit.

Algorithmic solutions to the problem of assessing the information impact on the electorate during election campaigns

In the article, to solve the problem of assessing the information impact on the electorate during election campaigns, algorithmic solutions, including a mathematical model, a numerical scheme and algorithmic implementations, are formed. This assessment is reduced to determining the instantaneous values of the number of voters who prefer a candidate (party), taking into account: the positive or negative stochastic nature of the impact of mass media; interpersonal interaction; two-step assimilation of information; the presence of a variety of mass media, social groups and a list of candidates. The mathematical model is based on a generalized model of information confrontation in a structured society and, with the introduction of stochastic components in the intensity of agitation, it is reduced to solving the FokkerPlanckKolmogorov equation. For its study in the formulation of the Galerkin method, a numerical scheme is proposed and the order of its convergence is determined. In relation to the basic procedures of the numerical scheme, the features of the algorithmic implementation are clarified.

Generation of ultra-short pulses using the Wilkinson adder

In this work the possibility of increasing the amplitude of ultra-short pulses and formation of a monocycle Gaussian by adding signals from several oscillators was investigated. For this purpose, the ring adders of Wilkinson design were used. The design of which has been chosen due to low losses and high input decoupling. The S-parameters of the adders with different geometrical parameters have been simulated in the frequency band up to 5 GHz. The obtained results coincided with the experimentally measured characteristics. The monopulse amplitude was increased and a bipolar pulse shape was formed by adding ultrashort pulses of equal and different polarities using the adders. This approach allows you to adjust the parameters of the output signal by adjusting the delays of the triggering signals.

Quasi-harmonic self-oscillations in discrete time: analysis and synthesis of dynamic systems

For sampling of time in a differential equation of movement of Thomson type oscillator (generator) it is offered to use a combination of the numerical method of finite differences and an asymptotic method of the slowl-changing amplitudes. The difference approximations of temporal derivatives are selected so that, first, to save conservatism and natural frequency of the linear circuit of self-oscillatory system in the discrete time. Secondly, coincidence of the difference shortened equation for the complex amplitude of self-oscillations in the discrete time with Eulers approximation of the shortened equation for amplitude of self-oscillations in analog system prototype is required. It is shown that realization of such approach allows to create discrete mapping of the van der Pol oscillator and a number of mappings of Thomson type oscillators. The adequacy of discrete models to analog prototypes is confirmed with also numerical experiment.

Singular integral equation for an electric dipole taking into account the finite metal conductivity from which it is made

A singular integral equation for an electric dipole has been obtained, which makes it possible to take into account the finite conductivity of the metal from which it is made. The derivation of the singular integral equation is based on the application of the Greens function for free space, written in a cylindrical coordinate system, taking into account the absence of the dependence of the field on the azimuthal coordinate, on a point source located on the surface of an electric dipole. Methods for its solution are proposed. In contrast to the well-known mathematical models of an electric dipole, built in the approximation of an ideal conductor, the use of the singular integral equation obtained in this work makes it possible to take into account heat losses and calculate the efficiency.

Ellipsometry of thin films of biological objects under conditions of total internal reflection

An analysis of the ellipsometric parameters of the reflected light from the prism test material air system is carried out when circularly polarized light is incident on it under the conditions of the onset of the phenomenon of total internal reflection. At the onset of total internal reflection, the ellipsometry parameter shows high variability with the angle of incidence, in contrast to the parameter r0. It is shown that TIR occurs when the angle of incidence is not equal to the critical angle of the adjacent media for two different materials, these angles differ from each other. In the case of a film, the TIR phenomenon occurs at an angle equal to the critical angle at the prism-air interface and does not depend on the film material. The results obtained show the high efficiency of using the ellipsometric method together with circularly polarized incident radiation for diagnostics of thin films made of biological material.

Features of generation and propagation of the extremely low frequency waves excited in the ionosphere under the powerful HF radioemission influence

The experimental results of the extremely low frequency emission characteristics excited in the outer ionosphere under the ionospheric plasma heating by high-latitude EISCAT facility are presented. The experiments have been conducted in the period of 20062010 yr. using two main schemes of extremely low frequency generation including the impact of the heating facility amplitude modulated emission and two unmodulated pump waves with the frequency detuning. In-situ measurements of the plasma wave disturbances were performed at the outer ionosphere heights using on-board equipment of DEMETER microsatellite. In work the spatial, amplitude and spectral characteristics of the generated extremely low frequency emissions are determined. It is shown that the characteristic size of the extremely low frequency emission is about 400600 km along the trajectory of the DEMETER microsatellite. The registration area spatial position is determined by both the applied generation scheme and the background plasma density distribution. The extremely low frequency emission electric field strength at the Earths outer ionosphere heights is 50330 V/m.

Joint application of radar visibility reduction and anti-radar masking technologies to protect aircraft from remote monitoring systems

Using spectral energy equations of transmission-reception of wave processes in radio channel with scattering on object and direct radio channel, analysis of energy ratios of information signals and active masking interference at inputs of receivers of remote monitoring systems is carried out. Measures to reduce visibility are aimed at changing the reflective signatures of objects in the interests of reducing the de-masking features contained in secondary electromagnetic radiation to limits that exclude the performance of radar monitoring tasks at established distances and time intervals. Active interference is designed to mask information signals in receiving channels of radar at power that does not allow detecting their designers by passive radar. In case of joint application of not iceability reducing devices and active jammers, radar range reducing coefficient is determined by product of coefficient characterizing possibility of autonomous masking of information signals and coefficient achievable due to reduction of secondary electromagnetic radiation power in the second degree. The laws of increase of aircraft stealth from radar observation with joint application of technologies of reduction of radar visibility and masking by intentional interference created from sides of protected objects and from assigned points have been investigated. In order to maintain the desired signal-to-noise ratio at the output of the receiver with a decrease in the duration of the probing signal, it is necessary to proportionally increase the density of the emitted energy. With given antenna sizes, the maximum signal transmission range is proportional to the root square of their cyclic carrier frequency; increase of this parameter leads to increase of partial coefficient of directional action and effective area of antenna. With a decrease in the cyclic frequency of the carrier of the probing signal, inorder to maintain the required directional properties of the antennas, it is necessary to increase their dimensions.

Investigation of CIE color spaces for differences in color differentiation thresholds in different regions of the color locus

The equidistance of the color space plays a significant role in determining the color difference in color transmission systems. Strictly equal contrasting color spaces can be considered only those color spaces in which equal changes in the visual perception of color are provided with an equal change in the color coordinates in this color space. Currently, the International Commission on Lighting (CIE) has adopted a number of color spaces called equal-contrast. The article presents the results of the study of color spaces adopted by CIE for equal contrast, i.e. on the differences in the thresholds of color differentiation in different areas of the color locus. The article investigated such color spaces as CIE 1931 (RGB), CIE 1931 (x, y), CIE 1960 (u, v), CIE 1976 (u*, v*), CIE LAB (a*, b*).

Antenna array with switching scanning in elevation plane

It is known that the most reliable communication in hard-to-reach places such as the Arctic, Tundra, Taiga is satellite communication [1-5]. Therefore, for satellite communications, it is necessary to develop your own antenna arrays. This article discusses a waveguide-slot antenna array with a Luneburg lens for a mobile satellite communications terminal, which provides a continuous and stable signal. This antenna operates in the 10.9 to 14.5 GHz frequency range. Possesses vertical polarization. The overall dimensions of the antenna array are: diameter of the diagram-forming lens 256 mm (thickness 5 mm, material FLAN 2.8 (epsilon 2.8, tangent delta 0.0015)); waveguide length 600 mm (internal section 10.5 mm by 5 mm, filling FLAN 2.8). Slotted waveguide antennas and lens are made of standard FLAN 2.8 material (epsilon 2.8, tangent delta 0.0015) 5mm thick, foiled on both sides. There are 17 coaxial cables to the HF switch (equal lengths are not required), the scanning step in elevation is 5 degrees. When using 54 waveguide-slot antennas and 18 switch inputs, a scanning sector in elevation of 90 degrees is provided. All the nodes were pre-modeled separately a cylindrical Luneburg lens with suitable waveguides, excited by slits; slotted waveguide antennas; coaxial-waveguide transitions.