ON THE “TREE” VERTICAL ELECTRIC ELF ANTENNA
E. A. Velichko, A. P. Nickolaenko
Development of new antennas for reception of radio signals was and remains an actual problem. We model and estimate the efficiency of unusual design of the vertical electric antenna detecting ELF (3…3 000 Hz) radio signals. The antenna must be sensitive to the vertical electric field of radio waves traveling in the spherical Earth–ionosphere cavity at frequencies of global electromagnetic (Schumann) resonance ranging from 4 to 40 Hz. It is formed by a couple of electrodes fixed at the tree trunk at different heights separated by several meters. Such a design is unusual, and its workability might seem dubious. We show with the help of model computations that the tree antenna is a rather effective ELF sensor, especially in fair weather condition. We also discuss the requirements for the tree antenna pre-amplifier.
THE KEY ALGORITHM OF A MODE-MATCHING TECHNIQUE FOR THE ANALYSIS OF RESONANCE POSTS, TEE, TURNSTILE AND OTHER TYPES OF MULTIPORT JUNCTIONS
A. A. Kirilenko, D. Yu. Kulik, S. A. Steshenko
While designing waveguide junctions, one of the actual tasks is the development of a mode-matching technique for calculating heterogeneities given in different coordinate systems. This paper presents the method for calculating multiport junction using the fields coupling in radial and rectangular waveguides. We proposed a modification of this method for junctions with several shorted ports. The accuracy and convergence of this method were researched.
THE ANALYTICAL-NUMERICAL METHOD OF SOLVING THE PROBLEMS OF ELECTROMAGNETIC WAVES DIFFRACTION BY CIRCULAR RADIALLY INHOMOGENEOUS MAGNETODIELECTRIC CYLINDERS
A. V. Brovenko, P. N. Melezhik, S. B. Panin, A. Ye. Poyedinchuk
We suggest an analytical-numerical method for determining the diffraction characteristics of the plane linearly polarized electromagnetic wave scattered by a circular inhomogeneous isotropic magnetodielectric cylinder, which material parameters depend on the radial coordinate. The method is based on the construction of special solutions to Cauchy problem for Riccati equation and allows within a unified approach to investigate the processes of wave diffraction by both radially layered and continuous magnetodielectric cylindrical inhomogeneities. The efficiency of the proposed method was demonstrated by several examples of numerical solution of diffraction problems for circular non-uniform isotropic dielectric cylinders. We studied the total cross section of Luneberg lens for a number of focal parameters and the behavior of its field longitudinal component at resonant frequency when geometrical parameters vary.
COMPARISON OF LONG-TERM ANTARCTIC OBSERVATIONS OF SCHUMANN RESONANCE WITH CALCULATIONS ON THE BASIS OF A TWO-COMPONENT OTD-MODEL
Ye. I. Yatsevich, A. P. Nickolaenko, A. V. Shvets, A. V. Koloskov, O. V. Budanov
Organization of continuous observations of Schumann resonance (SR) opens up the possibility of permanent monitoring the lower ionosphere and global storms. The existing methods for monitoring thunderstorm activity with SR are developed in detail only for point sources. However, the current models of radiation sources are too simplistic. In this connection, the development of semi-empirical source models, in which the intensity distribution is determined by the data from satellite observations of global storms, becomes very important. The paper compares the long-term experimental SR data accumulated in the Ukrainian Antarctic Station “Akademik Vernadsky” with the results of calculations of SR in the two-component OTD-model. It is shown that the model, despite the detailed distribution of lightning sources according to optical observations from space, is consistent with the experiment only partially. On the daily time scale, the two-component OTD-model quite well reflects the position of the main maximum of the global storms and their intensity, but the position of individual sources is described not precisely enough for an adequate representation of the diurnal variations in peak frequencies. The model describes quite well the annual and interannual variations in peak frequency of the magnetic components Hy. It is shown that the inter-annual variations of peak frequencies can be attributed to a change in height of the ionosphere and drift sources from year to year, and the long-term drift of the peak frequency is associated with the modification of the ionosphere during solar cycle.
FOCUSING THE VERTICAL ELECTRIC DIPOLE RADIATION BY PENDRY LENS
O. M. Stadnyk, O. O. Silin
The flat lens conception was considered in the pioneering work of V. G. Veselago, who considered the possibility of electromagnetic waves propagation in media with simultaneously negative permittivity and permeability (according to modern terminology – in the left-handed metamaterials). Later, J. B. Pendry put forward the idea of so-called “superlens”, the resolution of which would exceed the diffraction limit. In view of the prospects for the practical applications it has caused a discussion on the possibility of antiparallelism of phase and group velocities and the actual superresolution implementation for the source in the form of a monopole. However, using the ray theory approximation reduced the generality of the results, neglecting losses radically distorted them, and errors in the theoretical analysis led to the wrong physical interpretation. In this paper, we obtained a rigorous solution to the problem of focusing radiation from elementary electric dipole located perpendicularly to the plane layer of finite thickness made of the left-handed metamaterial with absorption. Spatial distribution of the electromagnetic field in the layer, as well as the incident and reflected fields at various heights of the dipole, layer thickness and losses in each environment are numerically simulated.The analysis of the calculated spatial structure of the electromagnetic field confirmed the focusing ability of the interfaces between ordinary and left-handed media, as well as a flat lens.
A. V. Shvets, A. P. Kryvonos, V. K. Ivanov
The task of measurements of the narrowband signals emitted by navigation and communication radios and broadband signals – radiation lightning arises in studies of the lower ionosphere by radio occultation of the Earth-ionosphere waveguide by low-frequency radio waves. Creating a universal receiver set for synchronous measurements of natural and artificial signals is of interest for increasing the information content of the data. The article discusses how to optimize the parameters of magnetic and electric field sensors to provide required bandwidth, dynamic range and matching with the input circuits of antenna amplifiers for noises. We present the algorithms for calculating the design parameters of the field sensors and a description of the pro-program-hardware complex for measurement of pulse and narrow band electromagnetic fields in the ELF and VLF ranges. The software part of the complex, implemented on a personal computer, allows estimating the absolute level, spectral composition, and polarization characteristics of the recorded pulse and narrowband fields in real time and storing the data around the clock.
DEVELOPMENT OF A RAIN GAUGE WITH ENHANCED ACCURACY AND HIGH RAPIDITY WITH NUMERICAL INDICATION OF RAIN RATE TIME DEPENDENCY
Yu. V. Levadnyi , Yu. I. Malyshenko, T. E. Chistova
Heavy rains considerably attenuate radio signals transmitted by modern millimetre wave high-speed communication lines. Therefore, this interference in the form of fast and deep changes of rain rates demands further investigations. Industrially manufactured rain gauges are not suitable for these investigations because of their inertia and insufficient precision of measurements. In this connection in this work the tipping-bucket rain gauge, has been modified and made. As a result the precision has lightly improved but the rapidity – more than in ten times (up to a few seconds in heavy rains) owing to considerable diminishing the cuvette size and weight and also due to configuration which removed drop adhesivity on its surface. The inclusion of an inexpensive microcontroller into the gauge composition also increased its precision and provided a better display of rain rate values on a built-in monitor and interface to a computer for registration.
I. M. Mytsenko, D. D. Khalameyda
Features of construction of mm-band and cm-band radiometers based on satellite low noise blocks (SLNB) are examined. The characteristics of the developed and constructed radiometer layout are presented. The experimental results are shown and compared with the published data. The possibility of using SLNB as an HF intermediate amplifier of mm-band radiometers and two-bandwidth radiometers is examined. A conclusion about receiving apparatus has been made.
INTERACTION OF A FLOW OF CHARGED PARTICLES WITH EIGENMODES OF A DIELECTRIC CYLINDER
Yu. O. Averkov, Yu. V. Prokopenko, V. M. Yakovenko
Nowadays a good deal of attention is focused on problems of generating electromagnetic oscillations on the basis of the interaction of charged particles with the structures containing dielectric and plasma-like media. This is due to the sufficiently high efficiency of conversion of the electron beam kinetic energy into electromagnetic radiation. The currently available theoretical results give only qualitative descriptions of experiments. Therefore, it is important to give a detailed description of such effects maximally close to the real conditions of the experiment. In this connection the detailed theoretical study of the instability of the non-relativistic infinitely thin tubular beam of electrons moving in a vacuum above a dielectric cylinder has been performed. It has been shown that either Cherenkov effect or anomalous Doppler effect occurs in relation to the distance (the impact parameter) between the beam and the dielectric.
TERAHERTZ TRANSVERSE-MAGNETIC-POLARIZED WAVES LOCALIZED ON A LAYERED SUPERCONDUCTOR DEFECT IN PHOTONIC CRYSTALS
S. S. Apostolov, D. A. Iakushev, N. M. Makarov, A. A. Shmat’ko, V. A. Yampol’skii
We theoretically study eigenstates of electromagnetic field inside a one-dimensional photonic crystal containing a defect slab of layered superconductor. Basing on the transfer matrix formalism along with the electrodynamics of Josephson plasma, we obtain the dispersion relations describing the THz electromagnetic modes localized on defect. We consider both symmetric and antisymmetric configuration of defect in photonic crystal. The comparison of the dispersion spectra of the localized states for the layered-superconducting defect and the pure insulating defect reveals the features of the studied system.
O. V. Botsula, К. H. Pryhodko, V. A. Zozulia
The development of millimeter and terahertz wave ranges is one of the main objectives of radiophysics. However, there are not many active elements that can operate in those ranges. Impact ionization in wide gap semiconductors is a fast process and can be used in active elements operating in these ranges. In this paper the charge transfer in short diodes (the length of the active area is less than 0.3 m) is considered. The purpose of the study is to determine the appearance conditions and peculiarities of impact ionization. The influence of impact ionization on devises characteristics is determined. The possibility of creating localized high electric field region is shown. The field magnitude is enough for obtaining impact ionization. It is a possibility to operate the impact ionization by changing the AlzGa1–zN composition distribution along the diode. The result of the study is the determination of properties of impact ionization in the proposed structures. They can be used for further detailed analysis of physical processes of the structures and their manufacturing.