TWO-DIMENSIONALLY PERIODIC GRATINGS. PART I. INITIAL BOUNDARY-VALUE PROBLEMS AND EXACT ABSORBING CONDITIONS FOR THE RECTANGULAR FLOQUET CHANNEL
Velychko L. G., Kryvchikova A. A., Sirenko Yu. K.
The paper presents the analytical results forming a theoretical basis for numerical solution of the problem on the electromagnetic wave scattering by two-dimensionally periodic structures in the time domain. The mathematically rigorous formulation of the corresponding initial boundary-value problems, which involves, particularly, the exact absorbing conditions on virtual boundaries in the cross-section of the rectangular Floquet channel is given. The use of these conditions allows one to reduce the original initial boundary-value problem with an infinite domain of analysis to the equivalent closed problem, whose domain of analysis is bounded and which can be solved numerically by the well-known finite-difference algorithms.
TWO-DIMENSIONALLY PERIODIC GRATINGS. PART II. SOME REGULARITIES IN THE BEHAVIOR OF NONSTATIONARY AND STEADY-STATE FIELDS IN THE RECTANGULAR FLOQUET CHANNEL
Velychko L. G., Kryvchikova A. A.
The analytical results describing some important characteristics of the pulsed and monochromatic waves propagating in regular regions of the rectangular Floquet channel (in the reflection and transmission zones of two-dimensionally periodic structures) are presented in the paper. These results are associated basically with mathematical formulation and physical interpretation of the energy conservation law and the reciprocity relations.
INFLUENCE OF THE STUB IN THE PARTLY SHIELDED QUASIOPTICAL DIELECTRIC SEMIDISK RESONATOR ON FREQUENCY OF GUNN-DIODE OSCILLATOR STABILIZED BY IT
Krivenko E. V., Kirichenko A. Ya., Lutsenko V. I., Kogut A. E.
Possibility of frequency tuning of a Gunn-diode oscillator by means of inhomogeneity in metal or dielectric stub , injected on a partly shielded quasioptical dielectric semidisk resonator is considered. The characteristics of frequency tuning on oscillator for different type of oscillations and a stub from different materials are shown. A model which allows to estimate the influence of stub on the resonator on its own frequency and oscillation frequency of oscillator stabilized by it is worked up.
ACCURACY OF ANALYSIS OF OPTICAL DIFFRACTION IN RELIEF GRATINGS BY COUPLED WAVE METHOD
Fitio V. M., Yaremchuk I. Ya., Bobitski Ya. V.
The convergence of coupled wave method (CWM) for the analysis of diffraction in certain optical relief gratings and near definite infrared wavelength range was investigated. It is shown that dependence of the transmission on number of coupled waves in metallic gratings with narrow slits (rectangular relief) monotonically tends to a value with error O(1/N³) for TE polarization, in the presence of the resonance and for TM polarization - with error, which oscillates relative asymptotic value within ±O(1/N³). Error in transmittance is less than 0.001 for TE polarization and 0.005 for TM polarization using 101 coupled waves. Error for both polarizations decreases monotonously by the expression O(1/N³) if is rectangular dielectric relief grating. But there are some minor deviations from this curve. Errors of calculation are smaller than 10–5 and 10–3 at N = 101 for waves of TE and TM polarizations, respectively. If the dielectric permittivity of the grating environment is changing as cosines, then diffraction efficiency with increasing number of coupled waves very quickly tends to the asymptotic value.
USING PRINCIPLE OF MINIMUM EXTENT FOR SPATIAL SPECTRUM EXTRAPOLATION OF COMPLEX-VALUED SOURCES
Borulko V. F., Vovk S. M.
Spectrum extrapolation problem for complex-valued radiation sources with unknown support is considered. For solving extrapolation problem the principle of minimum spatial extent of radiation sources is used. Scalar and vector versions of functional of quasi-extent are proposed. Based on this versions non-linear optimization problems are formulated and approach using gradient method is proposed. Numerical simulations for cases of one and five complex-valued radiation sources are presented.
A WAVEGUIDE IRIS WITH VERTICAL STEPPED SLOT AND A BANDPASS FILTER BASED ON SUCH A IRISES
Kirilenko A. A., Prikolotin S. A., Senkevich S. L.
The simple configurations of rectangular waveguide units able to produce a narrow band resonance of total transmitting the dominant wave are suggested. They are the irises with stepped slot which connects the opposite waveguide walls. It was shown that the total transmitting phenomenon is based on the excitation of the complex frequency eigen oscillation. A nature of the dependences of real part and Q-factor of such an oscillation on the slot geometry are revealed. A three-section bandpass filter having such the irises as the resonators is presented as well.
Khomenko S. I., Khlopov G. I., Khalameyda D. D.
Measurement results of refraction gradient during a half of the year with the help of a radiointerferometer measuring arrival angle of radiosignals of geostationary satellite are described. Analysis and justification of obtained results are carried out.
SURFACE ELECTROMAGNETIC WAVES IN PLASMA-LIKE MEDIUM BORDERING ON A PERIODIC LAYERED STRUCTURE
Averkov Yu. O., Beletskii N. N., Yakovenko V. M.
Results of experimental study of double frequency sensing of microstructure parameters of liquid precipitation on the base of on earlier developed algorithm and by means of weather radar of type MRL-1 are described. The used algorithm provides single-valued reconstruction of microstructure parameters and allows to take into account signal attenuation in the rain. Obtained radar results are compared with data of fast-acting ground rain gage. Main calculating relations, parameters of experimental equipments and results of preliminary experiments are presented.
SURFACE STATE IN A FINE-STRATIFIED PERIODIC STRUCTURE IN A MAGNETIC FIELD
Bulgakov A. A., Fedorin I. V.
The problem of the surface electromagnetic waves localized at the interface between vacuum and fine-stratified periodic semiconductor-dielectric structure in an external magnetic field is studied. Such a structure represents a biaxial crystal with effective components of permittivity which depend both on physical parameters of the structure and on geometrical parameters. The dispersion equation is derived for the system under consideration. It has been shown, that surface polaritons in such structure exist above and below plasma frequency. Besides, owing to specificity of the fine-stratified structure, areas of surface waves existence can be tentatively divided into areas of strong and weak anisotropy. The characteristic frequencies and magnitudes of external magnetic fields, near which there is a significant change in the characteristics of surface polaritons are derived. The opportunity of efficient control of surface waves frequencies by means of an external magnetic field, thickness of the layers and the period of structure has been shown.
Volodenko A. V., Gurin O. V., Degtyarev A. V., Maslov V. A., Svich V. A., Senyuta V. S., Topkov A. N.
The influence of the misalignment of the plane mirrors for the metal waveguide laser cavity of terahertz range (l = 0.4326 mm) on energy losses and the mode composition of radiation is investigated. It is shown that misalignment of the cavity at the change of direction of the tilt plane of mirrors relative to the plane of polarization of the exciting radiation can have a significant influence on the characteristics of its lower asymmetric modes.
RESEARCH OF POWER CHARACTERISTICS OF ASCILLATORS OF MILLIMETRIC AND SUBMILLIMETRIC WAVES BASED ON ABRUPT P–N-JUNCTIONS
Lukin K. A., Maksymov P. P.
Numeral power characteristics of ascillators of microwaves are explored on the basis of abrupt Ge, Si and GaAs p–n-junctions with the permanent reversed bias. It is shown that excitation of ascillators is conditioned by interdependence of the electric field and avalanche current, which is observed at an avalanche current comparable on a value with the limit current of p–n-junction. Power, frequency and electronic efficiency of ascillators, is explored and comparison is executed with characteristics of IMPATT-diodes. It is shown that power and electronic efficiency of ascillators is substantially higher than at IMPATT-diodes.
RESEARCH OF NEW SOLID-STATE ACTIVE MEDIA ON THE BASIS OF INDUSTRIAL POLYURETHANE COMPOUNDS, ACTIVATED BY DYES
Nikolaev S. V., Pozhar V. V., Dzyubenko M. I.
New active media on the basis of industrial polyurethane systems T-809/T-863, T-813/Т-863 (Italy) and EU-29-1/HU-29-1 (Taiwan), activated by several Rhodamine and oxazine laser dyes have been created and investigated. Optical characteristics of these polyurethane compounds have been analysed, their compatibility with different dyes is determined and spectroluminescent characteristics of the received media have been investigated. Experimental samples of laser matrices on the basis of chosen polyurethanes were made and their lasing ability was investigated. Laser emission of microsecond duration from matrixes on a basis of T-809/T-863, T-813/Т-863 compounds, activated by Rhodamine 6G, Sulforhodamine 101, Oxazine 17 and Oxazine 1 was received. It is established that the power efficiency of laser emission depends on optical quality of the made samples.
Bekirov B., Ivanchenko I., Popenko N., Chernobrovkin R.
The comparative analysis of electromagnetic characteristics of the resonance cells as the rectangular and cylindrical resonators of X-band EPR spectrometers from the point of view of providing their maximum sensitivity for investigations of samples with a high conductivity has been carried out in this paper. The findings have confirmed the sensitivity increase of spectrometer at the optimal distance between the rectangular resonator wall and the conductive sample under test.
Kiseliov V. K., Makolinets V. I., Mitryaeva N. A., Radionov V. P.
There was conducted a research about the influence of terahertz laser radiation of hyper-high-frequency (HHF) range on the tumor processes in the organisms of laboratory animals. The way to improve long-term stability of gas-discharge HFO-lasers by use selective thermal stabilization of the resonator was designed for the research. This simplified the conduct of medical research in the clinical setting in which new results were obtained.