A certain aspect of the topological properties of the in plane components of the field of a system of two magnets have been experimentally studied. Vector plots of the inhomogeneous field were obtained using computer processing of magneto-optical images in the longitudinal and transverse sensitivity of the Kerr effect. The topological characteristics of the field were changed by applying a homogeneous bias field in the plane. It is shown that the transition from the initial inhomogeneous configuration to a homogeneous one occurs according to various scenarios. The application of the external field leads to the appearance of new singular points, the number of which is due to Poincare ''s theorem on the rotation of the vector field. It is shown that the transition from the initial inhomogeneous configuration to the homogeneous one occurs according to various scenarios through topologically non-equivalent structures and depends on the orientation of the resulting magnetic moment of the system relative to the observation plane.

FeNi films in circular shape with 3 mm in diameter obtained by magnetron sputtering in the presence of a constant magnetic field of various configurations are studied. The presence of a field created by a permanent magnet with a diameter of 1.2 mm, the magnetization of which is oriented perpendicular to the plane of the substrate, leads to the formation of a vortex-like magnetic structure in the film, characterized by diffuse domain walls. Keywords: thin magnetic films, induced magnetic anisotropy, magnetic domain structure, magnetron sputtering.

FeNi films in circular shape with 3 mm in diameter obtained by magnetron sputtering in the presence of a constant magnetic field of various configurations are studied. The presence of a field created by a permanent magnet with a diameter of 1.2 mm, the magnetization of which is oriented perpendicular to the plane of the substrate, leads to the formation of a vortex-like magnetic structure in the film, characterized by diffuse domain walls.

A method based on the magneto-optical Kerr effect is demonstrated, which makes it possible to quantitatively determine spatial dependences of the directions of an in-plane component of inhomogeneous magnetic field visualized by soft nanocrystalline films. The method consists in obtaining magneto-optical images of micromagnetic structures that are formed under the influence of an inhomogeneous field. Images in the longitudinal and transverse sensitivity of the Kerr effect are used to calculate the angular dependence of the directions of the unit vectors of this field under the assumption that the components of the field are proportional to the brightness of magneto-optical images. The field direction maps obtained in this way agree with model calculations for our magnets.

The results of magneto-optical and magnetometric measurements carried out on two-layer film structures of YIG/FeNi are presented. YIG films were grown by liquid-phase epitaxy, and FeNi films were deposited by magnetron sputtering. It has been established that an interlayer magnetic coupling takes place in the YIG/FeNi system, which is mainly due to magnetostatic interaction. Keywords: yttrium-iron-garnet, permalloy, interlayer coupling, magnetostatic and exchange interaction, magnetic domain structure.

Thermomagnetic processing of films of the finemet type with an easy magnetization axis in the plane under the action of a constant and rotating magnetic field was carried out in order to obtain an isotropic state. After heat treatment in a constant field, the easy magnetization axis was reoriented along the line of action of the field, as a result of which the domain walls were oriented along the new axis. After thermomagnetic treatment in a rotating field regions with different anisotropy patterns, including isotropic regions, were revealed.

In this work, the results of magneto-optical and magnetometric measurements carried out on YIG/FeNi film two-layer structures are presented. YIG films were grown by liquid phase epitaxy, and FeNi films were deposited using magnetron sputtering. It has been established that in the YIG/FeNi system the interlayer coupling is mainly due to the magnetostatic interaction.

Thermomagnetic processing of films of the Finemet type with an easy magnetization axis in the plane under the action of a constant and rotating magnetic field was carried out in order to obtain an isotropic state. After heat treatment in a constant field, the easy magnetization axis was reoriented along the line of action of the field, as a result of which the domain walls were oriented along the new axis. After thermomagnetic treatment in a rotating field, regions with different anisotropy patterns, including isotropic regions, were revealed. Keywords: domain structure, thermomagnetic treatment, rotating magnetic field.

The results of studies of an autodyne transceiver (AT) for advanced radar sensing systems of the atmosphere are presented. A mathematical model of the APP has been developed, presented in the form of an oscillator with a single-circuit oscillatory system under the influence of a request signal from the radar. The analysis of the dynamics of signal reception in the beat mode, when the frequency of the received signal is outside the synchronization band, as well as in the capture mode, when the frequency of the request signal falls into the synchronization band of the AT. The noise and energy parameters and characteristics of the microwave generators used as an AT are investigated. Calculations of dynamic, noise and energy parameters and characteristics of the AT are performed depending on the choice of the type of conductivity characteristic of the active element and the position of the working point on it, as well as on the conditions of connection of the AT with the load. The experimental studies of the AT were carried out on the example of a serial transistor microwave module of the MRS-3MK radiosonde at a frequency of 1680 MHz. The description of the structural scheme of the AT for an aerological radiosonde operating in the beating mode is given. It is shown that the sensitivity of the AT to the request signal is determined by fluctuations in the amplitude of the microwave module and the bandwidth of the intermediate frequency amplifier. It is established that the sensitivity of the AT is minus 110...120 dB/W, for measuring the inclined range of 250...300 km is enough to have a radar transmitter with a pulse power of 50...100 W, while its average power corresponds to 0.05...0.1 W.

In this work we obtained experimental and simulated images of in-plane component of the stray field created by a permanent magnet using indicator film technique and magneto-optical Kerr effect imaging system. The applied uniform magnetic field and the presence of the source singular point leads to the appearance of the saddle point. The increase of magnetic field leads to convergence of the two points and they annihilation at a critical field. If a relatively weak magnetic field comparable to the coercivity is applied, magnetooptical image with noticeable hysteresis is formed. For the external magnetic field range exceeding the coercivity, we demonstrated the possibility to derive the topography of the stray field created by the permanent magnet by tracking the position of the singular points.

Upper-air radiosondes, which transmit coordinate-telemetric information on the main meteorological parameters to the ground station, contain a transmitter and, in some cases, a receiver of GLONASS / GPS satellite navigation systems. The known methods providing electromagnetic compatibility of transmitting and receiving systems cannot be fully applied in this case, taking into account the specifics of the radio sounding system. This paper is devoted to the development and study of methods for reducing the influence of out-of-band emissions from a radiosonde transmitter on navigation signal receivers and other communication systems operating in close frequency bands.

The study of the atmosphere of our planet with the help of radiosondes is very important for various areas of human knowledge - this is aviation, agriculture, cosmonautics and military science. Meteorological radiosondes, which are launched twice a day in many parts of the world, emit signals that may interfere with ground, aviation and space communication systems. This article is devoted to the minimization of such influence.

Рассматриваются вопросы ударного возбуждения колебательной системы транзисторного сверхрегенеративного приемопередающего устройства в момент запуска импульсами тока для разных законов затухания к и их влияние на чувствительность и усиление в приемном режиме работы, определение условий достижения высокой чувствительности устройства к слабым внешним сигналам на основе анализа флуктуационных колебаний в приемном режиме работы, оценка полосы пропускания входного колебательного контура сверхрегенеративного приемопередатчика при нулевом значении затухания этого контура, а также оценка суммарного воздействия ударных и флуктуационных колебаний на параметры сверхрегенеративного приемопередатчика.

This paper shows that amorphous Finemet films can be used as a medium for visualization and topography of inhomogeneous magnetic fields. The intensity of magnetooptical images obtained in the geometry of the polar magneto-optical Kerr effect is proportional to the normal component of the inhomogeneous magnetic field. This allows us to construct two-dimensional topograms of the normal component of the magnetic field. The images observed in the geometry of the longitudinal magneto-optical Kerr effect carry information about the planar component of the field. The vector field of the plane component has singular points that are displayed by magneto-optical images. Applying an external homogeneous field leads to the appearance of new singular points and their motion. At special points, the plane component of the field is equal to the value of the external field. This allows you to display a planar component by recording the coordinates of specific points.

In the work on the basis of application of the monopulse method the directions of accuracy increase of spatial coordinates measurement of an aerological radiosonde of the atmosphere radio sounding supplied with the superregenerative transceiver in radar-tracking domestic system are discussed. It is shown that the use of information on amplitude and a phase of reciprocal radio impulses of the superregenerative transceiver on a request signal of radar station allows to measure more precisely the inclined distance and angular coordinates of a radiosonde. On the basis of statistical approach the assessment of measurement potential accuracy of inclined distance to a radiosonde is carried out.

Configurations of magnetic domain structure of gadolinium-cobalt amorphous films with a perpendicular anisotropy under the effect of spatially nonuniform magnetic stray fields produced by various miniature sources have been studied. The domain structure of the amorphous films has been shown to qualitatively and quantitatively reflect the symmetry and magnitude of the normal component of the nonuniform magnetic fields and, similar to iron garnets, can be used for topographying stray fields. New features of the domain structure have been found during the visualization of small-scale sources of stray fields, on the one hand, and fields characterized by a small gradient, on the other hand.

The structure of magneto-optic images of the planar component of stray fields on the faces of prismatic hard magnetic elements is determined experimentally and by means of computer simulation. Magnetooptical images were registered using the longitudinal magneto-optical Kerr effect. FeCo films with inplane anisotropy were used as indicator films. A qualitative explanation to the structure of magnetooptical images was given on the ground of the symmetry of the plane field, produced by hard magnetic elements. (C) 2018 Elsevier B.V. All rights reserved.