Begell House Inc.
Telecommunications and Radio Engineering
TRE
0040-2508
54
1
2000
Emission of Nonstationary Electromagnetic Fields by a Plane Radiator
2-15
10.1615/TelecomRadEng.v54.i1.10
Oleg Aleksandrovich
Tretyakov
V. Karazin National University of Kharkov, 4, Svoboda Sq; Kharkov, 61077
Oleksandr
Dumin
V. Karazin National University of Kharkiv, 4 Svobody Sq., Kharkiv 61022, Ukraine
The emission of nonstationary signals by a plane radiator is analyzed using the modal basis method. A system of evolutionary equations is obtained for the longitudinal field components. Each evolutionary equation contains time in explicit form. As an illustration, the emission of a step function into free space by a disk with a uniform current distribution is discussed.
Nonlinear Mechanisms of Formation of Large-scale Vortices in Atmospheres of Planets
16-27
10.1615/TelecomRadEng.v54.i1.20
Fedor Fedorovich
Kamenets
Moscow Institute of Physics and Technology, 141700, Institutski per., 9, Dolgoprudny, Russia
Ivan Ivanovich
Korobov
Moscow Institute of Physics and Technology, per. Institutskii 9, Dolgoprudnyi, Moscow oblast', 141700 Russia
Mikhail Fedorovich
Ivanov
Institute for High Energy Density of the Russian Academy of Sciences, 127412, Izhorskaya St. 13/19, Moscow, Russia
Vladimir Evgenievich
Fortov
Joint Institute of High Temperatures RAS, Russian Academy of Science, Moscow, Russia
Viktor Aleksandrovich
Galburt
Research Center of High Energy Density, Russian Academy of Sciences
Semen Samoilovich
Moiseev
Institute of Space Research, Russian Academy of Sciences
Oleg Grigorievich
Onishchenko
Institute of Space Research, Russian Academy of Sciences
Methods of the nonlinear dynamics of plasma in a magnetic field are applied to the explanation of the formation of long-lived vortex structures in atmospheres of large planets caused by the fall of large meteorites. Evolutions of perturbations in the Jupiter's atmosphere, which are formed due to collisions with large fragments of the Shoemaker—Levy 9 comet, are considered as an example. A mechanism is proposed that explains the observable vortex structure, power characteristics, and linear dimensions of traces produced by interaction of the comet debris with the atmosphere. Simplified equations of the evolution of large-scale vortices in shallow, horizontally nonuniform atmosphere are derived that take into account (latitude) irregularities of a zonal wind and effects of viscosity and thermoconductivity. It is shown that the evolution of vortex structure essentially depends on the velocity field of the zonal wind in the area where a fragment of the comet falls. The threshold energy of initial perturbation is estimated, at which large-scale, long-lived vortices start to arise.
Calculation of the Optimal Profile of an Interface Between an Output Gyrotron Window and a THom -Waveguide Channel
28-34
10.1615/TelecomRadEng.v54.i1.30
Aleksandr Borisovich
Zakalyukin
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine 12, Academician Proskura St., Kharkov 61085, Ukraine
The exact equations for the calculation of a symmetric THom mode transformer, obtained on the basis of the general equations for the exitation of longitudinally irregular waveguides with a circular cross section are considered. Results of simulating the waveguide transition and transformer, used as an interface between an output gyrotron window and a waveguide circuit, are presented.
Microwave Emissivity of Random Media with Vertical Structures
35-50
10.1615/TelecomRadEng.v54.i1.40
P.
Pampaloni
IROE-CNR, via Panciatichi 64, 50127, Firenze, Italy
G.
Macelloni
IROE-CNR, via Panciatichi 64, 50127, Firenze, Italy
S.
Paloscia
IROE-CNR, via Panciatichi 64, 50127, Firenze, Italy
R.
Ruisi
IROE-CNR, via Panciatichi 64, 50127, Firenze, Italy
Microwave emission from random media characterized by long vertical structures, such as wheat and rice, was investigated using experimental data collected at 10 and 37 GHz (vertical and horizontal polarizations) on vegetation and on an artificial experimental model.
The influence of single plant constituents on the total emission from crops was evaluated by means of measurements carried out on plants in natural conditions and after sequential cutting of fruits, leaves, and stems. In addition, the effects of spatial distribution of the scattering elements were investigated using an experimental model composed of various distributions of long, thin vertical dielectric cylinders attached to a reflecting screen. It was found that, when the cylinders are distributed in nearly circular clusters or in parallel rows, significant emission enhancement with respect to uniform distribution is detected at 10 GHz and at incidence angles smaller than 50°. In contrast, at 37 GHz the emission is lower for clusters and strongly dependent on the azimuth angle for the "row" form. Finally, the dependence of the optical depth and single scattering albedo on the plant water content was estimated from the emissivity of wheat, using a radiative transfer model.
Methods for Designing Optimal Phased Array Antennas with a Limited Field of View: a Survey
51-66
10.1615/TelecomRadEng.v54.i1.50
Sergei Petrovich
Skobelev
Antenna Department at JSC Radiophyzika, Moscow, Russia
A survey is given on the methods of designing optimal radiating structures for phased array antennas that form flat-topped element patterns, providing for the maximization of the array's gain within a given, usually small, scanning sector and using the least admissible number of controlled elements. The methods considered include the use of passive multiport networks, coupled dual-mode waveguides, protruding dielectric elements, corrugated structures, and quasi-optical networks for the excitation of the necessary overlapped subarrays
Exact Geometrical Optics Synthesis of Two-Surface Lens and Reflector Antennas
67-72
10.1615/TelecomRadEng.v54.i1.60
Vladimir B.
Tarasov
State Design Office “Yuzhnoye”, Dnepropetrovsk, Ukraine
Lev Davidovich
Bakhrakh
Russian Academy of Sciences, Applied Radioelectronics
The problem of exact geometrical optics synthesis of two-surface lens-type antennas with constant refractive index, realizing the point-to-point transformation of the wave fronts, is analyzed. A two-reflector antenna is a special case of such ones. It is shown that the exact solution of the mentioned transformation for very general conditions exists.
High-Permittivity Microwave Dielectrics
73-84
10.1615/TelecomRadEng.v54.i1.70
Yurii Mikhailovich
Poplavko
National Technical University of Ukraine, 37, Peremogi Ave, 03056, Kiev, Ukraine
Vyacheslav Vyacheslavovich
Meriakri
Institute of Radio Engineering and Electronics Russian Academy of Sciences, Moscow, Russia
This article is devoted to main physical properties of microwave high dielectric permittivity ceramics, including: (i) the nature of thermostability of low-loss microwave dielectrics that are used as dielectric resonators and substrates; (ii) the features of nonlinear low-loss paraelectric films which could be used in fast microwave phase shifters by the electrically controlling their permittivity; (iii) microwave permittivity dispersion in ferroelectric ceramics which are promising materials for microwave absorbent coatings.
Methods for the Evaluation of the Velocity of Light Based on Impedance Measurements of Superconductors
85-96
10.1615/TelecomRadEng.v54.i1.80
New mathematical methods are proposed and substantiated for the determination of the velocity of light. Methods based on impedance measurements of superconductors are used. Analytical formulas suitable for physical analysis and calculations are produced.