Telecommunications and Radio Engineering, 60(10,11 & 12)

V.I. Lutsenko, Ye.N. Belov, I.V. Lutsenko, and S.I. Khomenko
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkov 61085, Ukraine
The Troposphere Refraction Estimation by Attenuation Factor of Radiowave beyond-the-Horizon Propagation

A technique of the troposphere refraction properties estimation by attenuation factor of the TV signals on over-the-horizon path is proposed. The experimental results of attenuation factor and their statistical performances on over-the-horizon paths in the diffraction and long-distance tropospheric zones are presented. Using the approach proposed, these performances are recalculated in terms of equivalent gradients of the refraction factor. A comparison with the troposphere performance direct measurements using the spheres-probes was carried out. Seasonal and daily variability of the refraction gradients and attenuation was investigated. The empirical dependences of attenuation factor fluctuations variance on the effective gradient of the troposphere refraction coefficient index were derived.

I.M. Mytsenko and S.I. Khomenko
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkov 61085, Ukraine
Diagnostics of Microwave Propagation Conditions Through the use of Signal Reflection from Sea Surface

O.V. Sytnik
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkov 61085, Ukraine
Invariant Transformation in Identification Theory

A generalized approach to tackling the problems on identifying the condition of natural media and objects by means of invariant models is discussed. Ways and techniques for synthesizing models using the tensor analysis are examined. A physical object along with the observation system is presented. In this study a procedure for optimizing multiposition radiophysical systems meant for the retrieval of data on natural media and objects is suggested. This method is based on equivalent transformations of a topological graph. The linear or nonlinear case is considered, and owing to a series of successive transformations of initial-space coordinates it has become possible to arrive at the configuration of a model, which offers minimal losses as decision are made about a specific object.

B.M. Bulgakov^*, S.A. Kravchuk, T.N. Narytnik, V.V. Popovsky, and S.I. Tatarchuk
Kharkov National University of Radio Engineering and Electronics,
14, Lenin Ave, Kharkov, 61166, Ukraine
^*A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkov 61085, Ukraine
The Concept of Application of Millimeter and Submillimeter Electromagnetic Waves in Telecommunication Information Systems

The advisability of development of digital broadband communication systems of millimeter-wave and submillimeter-wave bands with short path is proved. Creation of such systems will assist in building integrated telecommunication information systems.

I.P. Panfilov and A.A. Scopa
Odessa National Academy of Communication, Odessa, Ukraine
Reliability of the Communication Link Consisting of Primary and Reserve Channels

The problem of increasing the reliability and efficiency of communication line consisting of a primary and a reserve channel have been considered. The algorithm of commutation of information flows between the channels has been proposed.

A.O. Puzanov
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkov 61085, Ukraine
Some Properties of Videopulse Soil-Layer Scattering with Continuous Variation in Frequency-Dependent Electrical Characteristics

The characteristic properties of nonsinusoidal radio wave scattering by natural soil layers under the intricate law of spatial variation in frequency-dependent electrical characteristics are discussed. Corresponding transient processes in aeration zones with typical mechanisms for humidity distribution are analyzed. Some experimental data (measured over a wide frequency band) on the electrical properties of natural media are found to be unfit for numerical simulation of georadar probing signal scattering by soil layers.

V.B. Razskazovsky and Yu.A. Pedenko
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkov 61085, Ukraine
Comparison of Elevation Angle Measurement Techniques over the Sea

Experimental results of research of special elevation angle measurement technique of a low-altitude radiation source in natural conditions over the sea surface are obtained and analyzed: an off-axis monopulse technique and a symmetrical patterns technique. The measurements are executed in centimeter and millimeter wave range on the path from hundreds of meters up to several kilometers at sea state 3. Comparison of their efficiency with the now widely used monopulse sum-difference amplitude technique is carried out. The results of experimental research are added with the computer simulation. Conclusions about efficiency of the tested techniques in concrete conditions are made. It is shown that the off-axis technique has a number of advantages over other technique practically in all conditions of test performance.

V.N. Gorobets, V.G. Gutnik^*, and F.V. Kivva
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkov 61085, Ukraine
^*Institute of Radio Astronomy, National Academy of Sciences of Ukraine
4, Krasnoznamennaya St., Kharkov 61002, Ukraine
Experimental Doppler Spectra of Radiolocation Signal Reflections from Fallen Ship Waves

The results of experimental investigations of radio wave backscattering from ship waves in their origin zone are presented. Particular attention has been given to the analysis of the Doppler spectra. The backscattering model describing the experimentally obtained results is offered. It is shown that the characteristics of the backscattered signal are determined by the velocity of the object.

А.А. Мinakov
Radio-Astronomical Institute, National Academy of Sciences of Ukraine
4, Krasnoznamyennaya St., Kharkov, 61002, Ukraine
Space Lenses

A review of investigation of natural lenses is presented, that was carried out in the Institute of Radio Physics and Electronics and in the Institute of Radio Astronomy of NAS of Ukraine during many years. Kharkov scientific school of "lensists" has been founded using an idea of lens effect of the terrestrial atmosphere, which has been for the first time formulated by the Ukrainian Academician Alexander Yakovlevich Usikov in 1961. For many long years, the school was being headed by the honourable worker of the Ukrainian science and technology, Professor P.V.Bliokh. The methods to calculate diffraction, statistical and geometric-optical characteristics of various natural lenses in a wide wavelength range have been developed by this school. Such lenses as the Earth atmosphere, solar corona, the shadow from the Moon in solar eclipses, and gravitationalal lenses are discussed in the work. Many of the results of theoretical efforts have been demonstrated experimentally.

V.G. Galushko and G.V. Lytvynenko
Institute of Radio Astronomy, National Academy of Sciences of Ukraine
4, Krasnoznamennaya St., Kharkov 61002, Ukraine
Application of the Frequency-and-Angular Sounding Technique to Recovering the Three-Dimensional Electron Density Distribution in the Ionosphere

An algorithm is suggested for recovering the electron density distribution in the ionosphere with allowance for horizontal-plane gradients, based on the frequency-and-angular sounding technique. The medium is assumed to be only slightly nonuniform, so that the perturbation method can be applied to solve the eikonal equation. As has been shown, the regular profile of the ionospheric electron density can be recovered from the group path length of the probe signal measured as a function of frequency. The horizontal plane gradients can be determined from equations relating variations of the phase path length to angle of signal arrive deviations from their unperturbed values. The efficiency of the algorithm suggested is illustrated by several examples of recovering model three-dimensional electron density distributions.

A.P. Nickolaenko, L.M. Rabinowicz, A.V. Shvets and, A.Yu. Schekotov^*
A. Usikov Institute of Radio Physics and Electronics, National Academy of Sciences of Ukraine
12, Academician Proskura St., Kharkov 61085, Ukraine
^*Institute of Terrestrial Magnetism, Ionosphere and Radio Propagation (IZMIRAN) Russian 0cademy of Sciences
Troitsk, 142092, Moscow region, Russia
Detection of Splitting of Shumann Resonance Eigenfrequencies

We present experimental results and theoretical interpretation, which prove that elliptical polarization of the horizontal magnetic field at the extremely low frequencies reveals the lift of the degeneracy of the resonance oscillations under the influence of the geomagnetic field. The sense of polarization remains permanent in the vicinity of resonance peaks owing to the supremacy of the radio waves propagating from west to east.

A.M. Gokov
V. Karazin National University of Kharkov,
4, Svoboda Sq., Kharkov, 61077, Ukraine
Development of the Method of Determining the Electron Molecule Collision Frequencies in the Ionospheric D-Region by the Partial Reflection Technique

The classic method of determining the electron-neutral collision frequencies by the partial reflection technique in the ionospheric D-region is developed in the case of using the experimental data obtained with measurement errors.

A. M. Gokov
V. Karazin National University of Kharkov,
4, Svoboda Sq., Kharkov, 61077, Ukraine
Simultaneous Determination of Electron Density and Electron-Neutral Molecule Collision Frequencys in the Ionospheric D-Region by a Partial Reflection Technique

Main approaches of simultaneous determination of the electron density and electron-neutral molecule collision frequencys in the ionospheric D-region by means of a partial reflection (PR) technique were considered. In order to obtain more information and to have a more accurate PR technique, its experimental testing was carried out. Using the experimental data, the methods were compared, practical recommendations were given to make more precise an accuracy of obtaining the ionospheric plasma parameters and to widen a height range under study.

A.M. Gokov and O.F. Tyrnov
V. Karazin National University of Kharkov,
4, Svoboda Sq., Kharkov, 61077, Ukraine
Peculiarities of the Middle Latitude Ionospheric D-Region Dynamics, Caused by the Solar Terminator

Using a partial reflection technique, there are carried out experimental investigations of electron density variations in the middle latitude D-region of the ionosphere, characteristics of partial reflection signals and radionoises during the morning and evening solar terminator passage. The electron density was found to increase by about 50-150% both during the terminator passage and after it. In order to explain such events, a hypothesis of electrons precipitating from the magnetosphere, which is caused by the solar terminator, was suggested. The main characteristic features during evening terminator passage are discussed.

I.G. Zakharov and M.V. Lyashenko^*
V. Karazin National University of Kharkov,
4, Svoboda Sq., Kharkov, 61077, Ukraine
^*Institute of the Ionosphere of the NAS and MES of Ukraine,
16, Krasnoznamennaya str., Kharkov, 61002, Ukraine
Comparison of the Experimental and Model Values of Total Electron Content in the Ionosphere over Eastern Europe

The values of total electron content in the ionosphere obtained by means of measurements of satellite signals at the Radiophysical Observatory of the V.Karazin National University of Kharkiv have been compared with the values calculated in term of the global empirical ionospheric models. It has shown that the models under consideration are representative of the space-time distribution of ionospheric parameters above Eastern Europe insufficiently exactly. The data of the Kharkiv incoherent scatter radar were used for the analysis of an ionosphere state. The factors that have the most profound influence on accuracy of ionosphere models and the possible ways of taking them into account have been considered.