1. Radiation from dual-mode circular waveguide excited by dominant and higher-order modes simultaneously
A.V. Shishkova, N.N. Gorobets
microwaves, multimode waveguide, diffraction, higher-order modes, Weinstein rigorous technique, Wiener-Hopf technique, radiation pattern.
Vestnik KhNU №712 Pages. 56-61
On the basis of Weinstein rigorous solution to the problem of electromagnetic mode diffraction at an open-ended circular waveguide the characteristics of radiation from multimode waveguides excited by H11 dominant mode and. higher-order modes (E01, and H01) simultaneously are calculated and analyzed. The calculation of radiation from waveguide with dual- mode excitation is carried out in the whole observation space and in wide frequency bandwidth, taking into account the higher-order mode transformation and currents leaking on the external surface of a waveguide.
2. Radiation of electromagnetic waves by the system of transverse and longitudinal slots in the wide wall of rectangular waveguide
antenna array, multi-frequency antenna, slot system, multimode rectangular waveguide
Vestnik KhNU №712 Pages. 25-29
The problem of radiation of electromagnetic waves by the double-frequency multielement slot array on a multimode waveguide was solved by the Galerkin's method. The radiating aperture is two systems of longitudinal and transverse slots in the wide wall of the rectangular waveguide. The power and directional characteristics of such structure were investigated. Thickness of the waveguide wall, interior and exterior interactions between slots were taken into account at calculations
3. Radiation of short pulses from the open end of waveguide
O.M. Dumin, O.O. Dumina, V.O. Katrich, Zheng Yu
transient field, modal basis method, evolutionary equations, impulse field irradiation
Vestnik KhNU №834 Pages. 63-67
The problem of transient electromagnetic field radiation from the open end of waveguide is solved in time domain by the analytical and direct numeral methods. The problem of impulse signal propagation in regular waveguide is converted to the finding of transient wave propagation operator by modal basis method. The application of the operator for the obtaining of time form of signal both for the time change in positive and in the negative direction permits to seek an arbitrary time dependence of field amplitude in any point of waveguide taking into account distortions due to wave dispersion. The correction of diffraction distortions of time form of wave and forming the short probe impulse on the waveguide aperture by the excitation of waveguide in the given cross-section by field with the previously calculated time dependence are considered . Numerical simulation of short impulse irradiation of layered medium with losses is carried out
4. Radiation of transient fields from the open end of coaxial waveguide with shifted internal conductor
N.N. Gorobets, A.N. Dumin, O.A. Dumina
transient field, coaxial waveguide with shifted internal conductor, TEM-wave, radiation
Vestnik KhNU №712 Pages. 42-46
The problem of the radiation from the open end of coaxial waveguide with shifted internal conductor excited with transient source is solved in time domain. The incident into the aperture TEM-wave in coaxial waveguide with time dependence in form of gaussian pulse is considered as a source. The influence of a flange on radiated field characteristics is examined. The application of dielectric insertions into the aperture for the increasing of radiation along normal to aperture is studied
5. Radioacoustic wind sounding of the atmosphere bo un dat y layer: history of the development and perspectives
Y. N. Ulyanov, V. I. Vetrov, N. G. Maksimova
radioacoustic, wind, sounding, atmosphere, boundary layer, profile, adaptation
Vestnik KhNU №756 Pages. 27-32
The article is devoted to the potentialities of the method of radioacoustic sounding when monitoring the vertical structure of the wind in the atmosphere boundary layer (ABL). A review of methods for radioacoustic measurements of the horizontal wind velocity and direction is based on the developments of the authors and their experience in this field as well as on the world experience. It is emphasized that the radioacoustic method for sounding the wind in ABL is perspective, since for the RAS equipment, there are not characteristic neither high levels of the electromagnetic pollution of the environment like for radiolocation wind profilers - radars nor loss of the serviceability at ligh levels of the ambient acoustic noise like for acoustic wind profilers - sodars.
6. Radiolocation complex for extra-atmospheric researches
A.F. Sorokin, A.A. Sorokin, N.N. Gorobets, O.V. Sokolova
radar, a, microwaves, space garbage
Vestnik KhNU №834 Pages. 25-30
The creation pulse radar is offered on the basis of radio engineering systems of the National centre of management and test of space means of Ukraine for the forecast asteroid of danger, cataloguing of space garbage, research of a solar crown, near a sun and interplanetary plasma, and also for radioastronomical researches of distant space. Is shown, that at use of large-sized aerials to a ADU - 1000 and P-400 such radar at length of a wave ~ 30 cm at heights ~ 105 м finds out objects with the minimal sizes ~ 0,7 cm. On a disk of the Sun the spatial sanction ~ 103 kms
7. Random inhomogeneous liquid medium as a continuous laser of low-intensity modulator for excitating sound in the medium
B. G. Yemets
laser, random inhomogeneous liquid medium, interference, temperature field, optical acoustical phenomenon, sound, excitation, modulation
Vestnik KhNU №853 Pages. 95-100
When a medium is irradiated by laser pulses, sound waves are excited in this medium, i.e., the well-known optical acoustical phenomenon occurs. To excite sound oscillations, the specific laser beam modulator is shown to be unnecessary. The role of the modulator can play the liquid itself, which is a random inhomogeneous medium. The real liquid contains suspended solids and gas bubbles of small dimensions (dust particles and the like) that move irregularly in space (fluctuations). As a result, the electromagnetic wave interference taking place in the liquid undergoes random changes. Consequently, the temperature field changes, and hence variations in the local pressure occurs (thermo-optical mechanism for exciting sound). The excitation of sound due to the laser irradiation of low intensity is observed in an increase in the gas bubbles dimensions in the liquid
8. RECTANGULAR WAVEGUIDE M.V.
millimeter range, parametric amplifier, oscillatory system, band of the reinforcement, relative noise temperature
Vestnik KhNU №806 Pages. 18-21
Semiconductor two-stage parametric amplifiers have been developed to be used in the input circuits of communication and navigation systems in the short-part of millimeter wave band. In the 60 to 65 GHz range, the gain is no worse than 15 dB at -3 dB level in 1 to 1.6 GHz bandpass. The noise temperature is no higher than 500K when the quasi-optical IMPATT oscillator is in using as the pumping generator.
9. Resonance phenomena occurring as a thin refractive cylinder diffracts the hertzian wave
Yu. I. Grebenyuk, N. G. Kokodiy, Khe Shi
diffraction, thin cylinder, refractive index, scattering, absorption, weakening, resonance
Vestnik KhNU №806 Pages. 33-39
On the basis of solutions to the wave equation, the efficiency of dispersing, absorbing, and weakening the electromagnetic field that a thin cylinder with a large refractive index diffracts has been estimated. The transverse and longitudinal distribution of the electromagnetic field inside and outside of the cylinder has been calculated. The resonance is found to increase the intensity of both the electromagnetic wave field inside the cylinder and the scattered wave outside. Inside the cylinder at resonance, a wave propagating along its surface arises, and under some conditions, a wave propagating through the cylinder is also generated. As the refractive index is increased, the wave tracks the cylinder surface more closely, and its intensity is progressively enhanced.
founded: 9 result (s)