2011, Vol. 2(16), № 3
DISPERSION CHARACTERISTICS OF PERIODIC WAVEGUIDE CONTAINING METAMATERIAL LAYER
O. P. Kusaykin, P. M. Melezhyk, A. Yu. Poyedynchuk
Using the generalized scattering matrix method, a spectral problem on determination the propagation constants of the TM eigenmodes of a periodic waveguide formed by a metamaterial layer and diffraction grating, is solved. The study of the eigenmodes dispersion characteristics was conducted in the frequency range where the metamaterial permittivity is negative. Both the effect of modes coupling and a new kind of interaction between surface waves of the waveguide were found, the conditions for their manifestation were determined.
RADIATION LOSSES OF THE LOCAL COUPLING ELEMENTS OF OPEN RESONATORS
V. V. Glamazdin, M. P. Natarov, V. N. Skresanov, A. I. Shubnyj
The results of experimental investigation of the radiation losses that take place under the open resonator excitation or energy output process are presented. Two methods of measurements were modified and used for investigations. One of them is based on the power measurements in open resonator and coupling waveguides (the method of power balance). The second method is based on the measurement of the resonator impedance and on the presentation of open resonator by equivalent circuit (the impedance method). The equivalent circuit which take into account the direct radiation of coupling element to free space and scattering of the resonant field by the coupling element was substantiated. Two types of coupling elements have been studied: the hole in the thin metal wall on the surface of the mirror which is connected to the rectangular waveguide and the narrow slot on the mirror surface which is smoothly transformed to rectangular waveguide. The reasons which decrease excitation efficiency and power output efficiency of open resonator have been found. Comparison of the characteristics of different coupling elements has been done. It has been shown that slot coupling elements are more effective generally, than hole coupling elements.
NONSPECULAR REFLECTION OF ELECTROMAGNETIC WAVES FROM TWO-DIMENSIONALLY PERIODIC GRATING OF SHORT-CIRCUITED COAXIAL SECTOR WAVEGUIDES
MULTIPATH EFFECT ON MEASUREMENT OF ELEVATION ANGLE OF LOW-LEVEL RADIATION SOURCE USING ROOT‑MUSIC ALGORITHM
V. B. Razskazovskiy, Yu. F. Logvinov, Yu. A. Pedenko
Influence of multipath propagation microwaves over the sea on accuracy of measurement of elevation angle of low-level radiation source by a spectral estimation root-MUSIC algorithm is investigated. The received signal was modeled by the design procedure of a field developed during last years over a rough surface at strong shadowing, applicable up to zero sliding angles. Errors of measurement of an elevation angle achieved by root-MUSIC algorithm has been compared with monopulse and off-axes technique. Advantages of method root-MUSIC are noted at angles equal to some tenth of the direction-finding antenna pattern width.
PARAMETRIC SOURCE OF ELF BURST
A. P. Nickolaenko
Changes are addressed in the global electric circuit that were caused by arrival of giant gamma burst from SGR 1806-20 to the dayside of the globe. Properties of relevant parametric source depend on the structure of the global electric circuit. We consider formation of discrete radio pulse in the framework of realistic exponential model profile of air resistance. We show that the air slab around the tropopause plays the crucial role in pulse formation. Spectral density radiated is inversely proportional to the frequency. Waveforms of parametric pulse caused by arrival of the gamma burst have been computed.
DOUBLE FREQUENCY PROFILING OF RAIN PARAMETERS
O. A. Voitovych, A. M. Linkova, G. I. Khlopov
The algorithm for signal processing of double frequency radar is considered which allows single-valued measuring of rain parameters in the area of small intensities (≤ 4 mm/h) and takes into account influence of signal attenuation in the rain with large intensities (≤ 20 mm/h) using proposed iterative scheme of calculation of microstructure rain parameters. It was shown by numerical simulation that developed algorithm provides recovery of heterogeneous profile of rain parameter with good accuracy in wide range of rain intensities.
S. I. Khomenko, G. I. Khlopov, D. D. Khalameyda
Results of development of the apparatus on the basis of interferometer for research of refraction of troposphere by means of measurements of arrival angle of geostationary satellite radiation are presented. Block diagram, parameters and accuracy studying results of the apparatus are described. Achieved parameters of the apparatus provide arrival angle measurement accuracy which is required to get a gradient of refraction index of exponential model of the troposphere.
ESTIMATION OF RAIN EFFECTS ON MICROWAVE RADAR PARAMETERS TAKING INTO ACCOUNT THE CUMULATIVE DISTRIBUTIONS OF RAIN RATE
Yu. I. Malyshenko, Yu. V. Levadnyi
It is known that short-term effects induced by heavy rain on microwave radar parameters have a few percent against the year duration. This allows radar developers to decrease additional energy potential which is intended for overcoming of rain-induced attenuation depending only on permissible radar outage time owing to the typical rains for region of radar disposal. According to this, the method for estimating probability of uninterrupted radar functioning in rains is given on examples of particular 10, 35, 70 and 95 GHz radars attracting rain rate statistical distribution for one Ukrainian province. The necessary for this methods specific rain attenuation and radar reflectivity dataset were also summarized in this work partially by means of original calculations and partially by means of analysis and generalization of published data. As results the modern computational models tested on empirical data and complemented by more precise original analytical dependencies are given to radar personnel for practical applications.
PLASMA FORMATION STRUCTURE INVESTIGATION BY DOPPLER RADAR METHOD
S. I. Khomenko, M. O. Khorunzhiy, A. N. Kuleshov, B. P. Yefimov
Stratified positive plasma column is studied using coherent homodyne receiving-transmitting measuring device. The estimation of effective scattering surface of plasma formation of stratified plasma column is given. Estimations of frequency peculiarities of signal scattering from stratified plasma, signal angle dependencies, scattering signal amplitude depending on discharge current and noise generator type have been presented.
D. V. Abdulkadyrov, N. N. Beletskii, S. A. Borysenko
The tunneling of electrons through a nonstationary tunneling junction in the framework of the one-quantum electron tunnel transition approximation is investigated. The effect of the thermal energy distribution of electrons in the emitter and collector of the tunnel junction is taken into account. The dependence of the high-frequency electron current on the frequency and applied dc bias voltage is found. The influence of the barrier asymmetry on the active and reactive parts of the high-frequency electron current is studied.
GENERATION AND FREQUENCY MULTIPLICATION BY DIODES WITH TUNNEL BOUNDARIES BASED ON GAAS
E. D. Prokhorov, O. V. Botsula, O. A. Klimenko
The current-voltage characteristics and the generation efficiency diodes with tunnel boundaries (TB) in structures of the «sandwich» based on GaAs are investigated. The effect of resistance between the contacts of the diode structure and the resistance in series with the TG on the efficiency of generation at the fundamental and harmonic frequencies is shown. Frequency limit of the diodes with TB is estimated. The possibility of harmonic generation and frequency multiplication using diodes with TG in the range of tens to hundreds of gigahertz is shown.
GRAPHIC MODELLING OF THZ GAS-DISCHARGE LASER RADIATION PULSE SHAPE
V. K. Kiseliov, V. P. Radionov
A technique for modelling the shape of the radiation pulse-pumped THz gas-discharge laser is presented. The initial data to be used for modelling are as follows: the size and the shape of a discharge-current pulse; discharge current-dependent radiated power; the dependence of radiated power upon the tuning control of a resonator at different pumping currents. The application of the above technique makes it possible to produce pulses of required shape and to select laser peak-efficiency operating conditions.