Radio physics and electronics

9-14

Authors: E. M. Ganapolskii

In this paper for the first time we have discovered and studied the analogy of the second order phase transition in spheri-cal microwave cavities with heterogeneity in the form of a metal ball. The transition occurs between the state when the ball is sym-metrically disposed relative to the side walls and the state with asymmetric arrangement of the ball. For these states the spectra of oscillations in 8-mm range were measured and on the basis of the obtained data the correlation coefficients of inter-frequency inter-vals were determined. It has been established that an integrable system of spherical symmetric cavity with an inner ball has a cor-relation coefficient close to zero, while for non-integrable systems with asymmetric arrangement of the ball, the correlation coeffi-cient C(1) > 0.2. Phase transition between these states occurs in a narrow range of eccentricity. The dependence of the distribution of inter-frequency intervals on the mean distance between the natural frequencies were determined and it was found that for an integrable system, this dependence is described by the Poisson function, and for non-integrable by Wigner distribution, which is typical for states with repulsion resonance lines and quantum chaos. Thus, it was found that a change in the symmetry of the microwave resonator leads to the second order phase transition, when the system becomes non-integrable cavity and is accompa-nied by quantum chaos.

20-31

Authors: A. Ya. Matveev, A. A. Kubryakov, A. G. Boev, D. M. Bychkov, S. A. Velichko, V. K. Ivanov, S. V. Stanichny, V. N. Tsymbal

In the article the validation of the multiangle method for spaceborne radar diagnostics of oil pollutions on the sea surface are described. The validation was performed by comparing the radar estimates of the mass and thickness of the polluted oil film with the numerical simulation results obtained by the new Floating Object Tracking System (FOTS) model of oil drift dynamics. Synthetic aperture radar (SAR) satellite Envisat-1 data of the oil-producing area “Oil Stones” in the Caspian surveillances were used for the analysis. FOTS model allows us to calculate the displacement and changing in the mass and size of the oil slick basing only on available satellite measurements and atmospheric reanalysis data. The model takes into account the main processes impacting on the oil slicks dynamics (gravitational spreading, advection transport, dispersion, emulsification, turbulent mixing and evaporation). The model allows to calculate the changes in thickness, and the oil slick displacements in the timeslot between two consecutive radar images, and to estimate spilled oil volume. Satisfactory agreement between the oil film thickness that was calculated by using radar measurements and oil drift model results is observed, which confirms the reliability of the radar multi-angle method. The work was performed as a part of the project 11140 with European Space Agency (ESA) and was supported by the Federal Target Program 1.2 “Study on the technology of monitoring and forecasting the water environment ecological state of the sea shelf: Agreement with the Russian Ministry of Education 14.604.21.0044”

40-47

Authors: Yu. P. Galuk, A. P. Nickolaenko, M. Hayakawa

The rapid development of computer technology allows for the direct numerical solution of the electromagnetic resonance problem in the Earth–ionosphere cavity. Either the two-dimensional telegraph equations (2DTU) or the finite element method in the time domain (FDTD) techniques are used. The direct solutions apply the same models of the conductivity profile of atmosphere as those applied in ordinary solutions. However, it is forgotten that these profiles are nothing else, but a convenient interpretation for the approximate heuristic relations for deriving the propgation constant. Since the full wave solution of the electromagnetic problem for such a profile does not coincide with the aproximate one, the direct numerical solutions must also deviate from the heuristic one. We apply the knee conductivity profile in the rigorous full wave solution and in the approximate solution and evaluate their devations

54-60

Authors: M. V. Milcho

There is a problem of designing convenient in use and not particularly expensive oscillators for mastering the sub-millimetre waveband. The backward wave oscillators (BWOs) provide good results in the long-wavelength part of the sub-millimetre waveband. However, their advancement in the short-wavelength part of the sub-millimetre waveband causes substantial problems. Existing technological opportunities do not allow to obtain extremely thin high-current-density electron beams necessary for this waveband. Application of the frequency multipliers could weaken requirements to the electron beams considerably. A clinotron-type oscillator can be used for bunching electron beam in the frequency multiplier. In the clinotron oscillator, a wide and comparatively thick sheet electron beam is directed at a small angle to the surface of the slow-wave structure and is partly dispersed on this surface. Clinotron provides output powers a few orders of magnitude greater than conventional BWOs of the same waveband. This is important for obtaining good (i.e., deep) bunching of an electron beam. In clinotron-type oscillators, it is necessary to investigate the process of dense electron bunching and to clarify the conditions of its use for bunching electron beam in a frequency multiplier. In this article, numerical simulation of electron bunching is conducted in the clinotron by means of our previously in-house designed special computer program, which takes into account the specifics of the clinontron operational regime. Three-dimensional motion of electron is investigated in the finite focusing (guide) magnetic field. As a result of numeral simulations, we find the effect of “layer-by-layer” bunching of the electron beam in a clinotron-type oscillators. The farther an electron layer is located from the surface of the slow-wave structure the later electron bunching in that layer occurs. We show that singling out the clinotron operating regime and the slope angle of the guide magnetic field to the surface of the comb allows one to ensure the formation of dense electron bunches in the part of the beam outside the clinotron slow-wave structure, where the second slow-wave structure (working in the power-catching regime) must be located. Thus, the principal possibility of the clinotron use for designing a frequency multiplier is proved.

68-72

Authors: A. A. Kurayev, V. D. Yeryomka, A. O. Rak

The equations of excitation of waveguides and resonators by foreign sources are used for solving problems in electrodynamics, microwave and terahertz electronics. The authors of several monographs describe the algorithm for solving the problem of excitation, presenting a waveguide (or a resonator) in the area of foreign currents as a regular one, and as a result in terms of orthogonality of eigen modes of regular waveguide in this area. In reality, foreign currents are set on excitation elements (pins, loops, slots and apertures in the sides of a waveguide or resonator), which transform the mentioned electrodynamics systems into irregular, diffraction and wave scattering take place in the area of foreign sources. Therefore, the well-known equations of excitation from the mentioned monographs cannot be applied for solving problems on excitation of irregular electrodynamics systems by foreign sources. In vacuum electron microwave devices this limitation is removed: foreign electric currents are formed by free electrons currents and excitation elements i.e. slots, loops and apertures are absent. However, there is another obstacle: in vacuum sources of microwave radiation unlike passive electrodynamics, the areas of excitation are not fixed in space, that is why transversal electrons phasing takes place. In this paper we formulated equations of excitation of waveguides and resonators by electron currents under transversal electrons phasing. Application of these equations considerably expands the area of solved problems in electrodynamics and vacuum microwave electronics (in particular, in electronics of gyro devices of new type).

78-82

Authors: V. P. Radionov, P. K. Nesterov, V. K. Kiseliov

Terahertz lasers are used as sources of radiation in different heterodyne radio physical devices. Stable frequency difference between the heterodyne and signal channels is required when using these devices. This paper describes the various ways of solving this problem. A scheme of terahertz laser with several resonators is chosen as an optimal solution. The technique of obtaining and stabilizing the difference frequency in each resonator has been proposed. This multi-line laser can be used in conventional schemes of the interferometers and polarimeters. This laser can also be used in other multichannel systems to obtain a simultaneous radiation with different frequency in channels. The frequency difference is restricted by an amplification band of a laser medium. This gives new possibilities for the application of THz lasers in measuring systems.

90-96

Authors: K. A. Lukin, D. N. Tatyanko, Y. A. Shiyan, L. V. Yurchenko, A. V. Bazakutsa

The paper presents the creation results of the optical low-coherent reflectometer based on spectral interferometry with a heterodyne frequency transfer into the radiorange that allows to measure distances of tens of kilometers. The reflectometer layout for micro-distances based on fiber-optic Fabry-Perot interferometer and broadband infrared source was designed, fabricated and tested. Based on these investigations the feasibility and advisability of using the low-coherence spectral interferometry method for reflectometry measurements of distances for fiber-optic communication lines was demonstrated.