GREEN SURFACE TENSORS IN MICROSTRIP ANTENNA THEORY
V. N. Kochin
As a result of microstip antennas compactness and technological effectiveness, they are widely used as independent transmission and receive antennas, and also as elements of phase antenna grids. Thus, there is no strict approach which allows to research microstrip antennas with different geometrical shapes. The new approach to the study of microstrip antennas with patches of different geometry has been suggested in this study. It is based on the application of the Green surface tensors for shielded magnetic-dielectric layer. The expressions for the Green tensor components have been obtained; they are based on electric surface currents. The examples of the offered approach to solution of the problem of microstrip antenna during approximation of given distribution of surface current and the problem of circular microstrip disk antenna with an axisymmetric excitation have been provided.
ANALOGY OF THE SECOND ORDER PHASE TRANSITION IN QUASI-OPTICAL MICROWAVE CAVITY RESONATOR
E. M. Ganapolskii
In this paper for the first time we have discovered and studied the analogy of the second order phase transition in spherical microwave cavities with heterogeneity in the form of a metal ball. The transition occurs between the state when the ball is symmetrically 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 intervals were determined. It has been established that an integrable system of spherical symmetric cavity with an inner ball has a correlation coefficient close to zero, while for non-integrable systems with asymmetric arrangement of the ball, the correlation coefficient 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 accompanied by quantum chaos.
GENERALIZED MODE-MATCHING TECHNIQUE IN THE THEORY OF MODE DIFFRACTION.
PART 4. RATE OF CONVERGENCE FOR PROJECTIVE APPROXIMATIONS
I. V. Petrusenko, Yu. K. Sirenko
In this part of the work, we continue consideration about the basics of the generalized mode-matching technique, which has recently been developed for the analysis of wave diffraction. The problem of analytical estimate of the rate of convergence of projection approximations to the operator Fresnel formulae is discussed. The unconditional strong convergence of these approximations to the true scattering operators was proved previously. For the canonical scalar problem of wave diffraction on the step discontinue in a guide a measure of inaccuracy for the approximations of scattering operators has been derived analytically. These projective approximations under consideration are the truncated Fresnel formulae for the reflection and transmission operators. It is shown that the problem can be solved by examination of strong P–convergence of projective representations of an amplitude scattering operator. An analytical estimate of the rate of convergence of approximations for the scattering operators under consideration has been obtained. The found order of approximations has been verified by numerical computation. The results obtained allow us to estimate the computational efficiency of the generalized mode-matching technique, which can be useful for numerical-analytical solution of various electromagnetic problems.
VALIDATION OF SPACEBORNE RADAR MULTI-ANGLE METHOD FOR THE SEA SURFACE OIL POLLUTIONS DIAGNOSTICS
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”.
DISTURBANCES OF LOWER IONOSPHERE ABOVE THE CENTER OF EARTHQUAKE AND ANOMALY IN THE GLOBAL ELECTROMAGNETIC RESONANCE SIGNAL.
PART 2. ANOMALIES IN THE POWER SPECTRA
A. P. Nickolaenko, M. Hayakawa
We model an effect of the ionosphere non-uniformity centered above the earthquake at Taiwan on the Schumann resonance records in Japan. The changes in the resonance spectra arise from the interference of the direct radio wave with the one reflected from the ionosphere modification above the earthquake. The disturbance model is used and it was described in the first part of this work. Solution of the Stratton-Chu integral equation is used for describing the wave diffraction and scattering. Observations of the Optical Transient Detector (OTD) satellite are used for modeling the spatial distribution of global thunderstorms. Computations showed that abrupt changes occur in the spectra of all field components resembling the observational results. The features of seismogenic anomalies are discussed.
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.
O. Voitovych, A. Zatserklyana, G. Rudnev, D. Khalameida, G. Khlopov, S. Khomenko
Fluctuations of signals scattered by clouds deal with turbulent processes, which strongly influence flight safety and contain information about physical phenomena in clouds. That is why remote sensing by weather radar is of great interest for diagnosis and forecast of meteorological phenomena that take place in clouds. But the majority of such radar use incoherent signal processing, spectral characteristics of which practically have not been described in literature, so in the paper we present the results of yearlong experimental study of incoherent signal fluctuations spectrums in 3 cm waveband reflected from clouds in 3 cm waveband as well as dissipation speed of turbulent energy. As it was shown the most probable velocity spectrum width is about l / 2f » 45 cm/s and mean square value is 27 cm/s, where l is operating wavelength and f is current frequency in signal spectrum. Also the maximums of radar reflectivity and dissipation speed do not coincide, at that the most number of turbulent cells of different dimensions are concentrated in upper cloud parts because of maximal influence of solar energy.
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.
M. V. Milcho, A. S. Tischenko, V. V. Zavertaniy, I. V. Lopatin, S. N. Teriohin
In comparison to backward wave oscillator (BWO) of O-type, requirements to the quality of electron beams are weakened in the frequency multipliers. Therefore, frequency multipliers may have a considerable perspective for mastering the sub-millimetre waveband, although, their output power is usually less than in the BWOs of the comparable waveband. Experimental works on the frequency multipliers are known in the millimetre waveband. In those devices, a resonator of klystron type, fed by an external power oscillator of the centimetre waveband, serves as the buncher section. The slow-wave structure of the comb type operates in the power-catching regime. We are certain that for the sub-millimetre waveband it may be possible to design a multiplier as a two-cascade clinotron-oscillator, which is simultaneously a modulating generator, a buncher, and a power-catcher. Numeral simulations showed that in the clinotron there exists the effect of “layer-by-layer” bunching of electrons in a sheet beam: the farther an electron layer is located from the surface of the comb, the later electron bunching in that layer occurs. In a remote layer, electrons form bunches outside the comb of the modulating part of the clinotron. Therefore, clinotron can be used as an electron beam buncher. The aim of the present work was an experimental verification of this possibility. In the paper, a simple design of a clinotron-multiplier is introduced, and the results of investigation of its operation are presented. In the buncher section of the clinotron, oscillations are generated with the wavelength of 2.8 mm. In the power-catcher section, a signal is generated with the wavelength of 0.935 mm. We also demonstrate the possible decrease in the magnetic field induction of the focusing (guide) magnetic field to 0.5÷0.3 T in this device, while for a BWO of the same waveband the necessary guide magnetic field is about 1.0 T.
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).
A. Ya. Kirichenko
Nowadays there are a lot of research, aimed at creation of sources of electromagnetic oscillations in the submillimeter range. Along with the search for new methods of generation, the attention is paid to the possibilities involved into known generators with long-term interaction of electron beam with the electromagnetic fields produced by periodical structures (clinotrons and generators of diffraction radiation). The fineness of the elements of such generators are often wrongly considered as the main obstacle for the creation of such generators. On the basis of experimental study of clinotrons operating in the millimeter-wave range of generation, two reasons that hamper the effective generation clinotrons in the submillimeter wavelength region are shown: decrease of the current density of the electron beam in the vicinity of the surface of the periodic structure, and dispersion of geometrical parameters of the periodic structure.
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.
V. I. Bezborodov, O. S. Kosiak, Ye. M. Kuleshov, V. V. Yachin
When constructing polarization radio measuring paths operating in the THz frequency range (0.1…10 THz) the differential phase sections (DPS) are widely used. The use of terahertz waves (THz) allows research in radio astronomy, radio spectroscopy, biology, medicine, physics of the atmosphere, etc. Due to the fact that in a terahertz wave range quasi-optical transmission lines are used the transfer to the optical principles of construction DPS using dielectrics having birefringence property, in particular, form birefringence seems to be very attractive. One of the important requirements when creating the DPS is their matching with free space. The paper represents the ways of matching structures with form birefringence in the form of a multilayer stack of alternating dielectric plates with different dielectric constants. Such an antireflection layer may be formed when one of the plates is projected over the surface of the birefringent dielectric structure. In the first case projecting plates have transverse grooves. In the second case plates are formed without grooves. For the calculation of such structures we used a numerical method of integral functionals in the frequency domain for full wave dispersion problem of plane monochromatic wave scattering from a lattice consisting of dielectric bars without loss. An experimental study of models of structures, which confirmed the possibility of matching with the methods discussed in the THz range was made.
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.
K. A. Lukin, V. Ye. Shcherbakov
A new approach to design of the self-organizing MIMO-system using European Union Dedicated Short-Range Communication (EU DSRC) standard for Vehicle-to-Vehicle Data Transmission (VVDT) within a highway area of 1 km in radius is proposed. The design method of self-organizing EU DSRC-VVDT MIMO-system provides the completely off-line operation of vehicle appointed by this system at the complete absence of base stations as a rule controlling mobile communication systems. The method suggested gives the possibility in practice to realize a Space-Code Division Multiple Access (S-CDMA) and the principles of data transmitting with the usage of broadband chaotic waveform sequences and unique binary pseudorandom sequences. In addition, these code signals give a potential capability for design of a self-organizing EU DSRC-VVDT MIMO-system without allocating a frequency or temporal channel for each vehicle and perform data reception on the searchless basis. Combination of spatially code channels separation (S-CDMA) and chaotic waveform coding for implementing CDMA-standard are distinguishing features of the suggested EU DSRC-VVDT MIMO-system. The key method idea is to associate the unique code for every car in the EU DSRC-VVDT MIMO-system not with a car, but with its current position on highway. A new method for the S-CDMA-code prescribing to each car within the working range of EU DSRC-VVDT MIMO-system enables usage of identical standard Tx/Rx equipment for all vehicles. The self-organizing MIMO-system allows to implement in practice, for the maximally possible amount of transport vehicles, the carrying capacity of channel close to Shannon's limit.