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The problem of reducing the side-lobe level of the radiation pattern of the trough waveguide antenna has been considered. To solve this problem, weighting the height of the elements of excitation has been used. For increasing the efficiency of the weighting, it is proposed to use a weight function that takes into account the losses of the exciting wave as it passes through the elements of the exciting...
Characteristics of semiconductor diodes as power indicators are studied. Rigorous electromagnetic model of direct problem of average detection is derived. Approximate models of the inverse problem for detector characteristic are proposed. Maximum errors of approximation for different orders of approximating polynomial and source resistance are calculated.
The paper discusses the problem of determining the complex eigenfrequencies of surface plasmons on a metal nanowire from the frequency spectrum of the scattered field. We use a fractional-rational approximation of the frequency spectrum based on continued fractions. Q-factors for low and high-order localized surface plasmon modes are investigated.
In this article the cross-platform software and hardware solution for LTE key performance indicators optimization are developed. There are two important conflicting indicators are explained and optimized — LTE user's throughput and cell throughput versus different power control parameter settings such as nominal power per resource block and alpha for fractional power control. The results graphically...
The possibility of complex reflection coefficient value estimation via discrete Fourier transform of output signals of equidistant probes in multiprobe measuring line is considered. This approach provides linear problem and explanation of known previous results. The general features of this approach and the holography with colliding beams are under discussion. The influence of noise on accuracy of...
The parameters of pulses reflected from non-periodic Bragg layered structures have been investigated. The specific structures such as asymmetric resonators with periodic Bragg reflectors and structures with chirp variation of the thickness of the “period” have been examined. The numerical investigations have been made both in Bragg band and outside it. The frequency characteristics of the structures...
The behavior of quasi-periodic and aperiodic (chirp) Bragg structures with thin lossy layers was examined. In order to determine the frequency dependence of the reflection coefficient transmission matrix method was used. A deep minimum of the reflection coefficient for any frequency is implemented by proper choice of the thickness of the last thin film and its optical distance to the substrate. The...
This paper describes some aspects of wideband (or ultrawideband) measurements of characteristics of antennas which does not require expensive anechoic chambers. The idea of the method is based on exciting the antenna under test by very short impulse which spectrum covers the band of interest and on analysis of spectra of the radiated signals. Reliability of the method is proved by comparison of simulated...
PbIn6Teio is a new nonlinear material with main transparency window 1.7–31 μm. For the first time optical properties were studied in the THz region, as well as DFG of CO and CO2 laser theoretically and experimentally. The simulation indicated that DFG spectrum can contain dozens of strong lines within 10–13 μm at fixed phase-matching angle. As well CO and CO2 laser lines can be down-converted, respectively,...
The time delays of pulses reflected from periodic and non-periodic Bragg layered structures have been investigated. The specific structures such as Bragg reflectors and structures with chirp variation of thickness of the “period” have been considered. The calculation has been carried out under the conditions that carrier frequency is in the vicinity of the Bragg resonance values. The parameters of...
The solution of the excitation problem for the biconical cavity analysis by overlapping domain decomposition in combination with the collocation method has been examined. For determination of eigenfrequencies, the fractional-rational approximation of the cavity frequency response with its excitation has been used. Using the proposed approach the cone angle dependence of the eigenfrequencies of the...
The paper is devoted to the discussion of the main principles of the non-perturbative quantum-mechanical approach to the description of a single atom interaction with multicomponent laser fields. The main advantage of the theory is that the authors use a basis of “an atom in the field” eigenfunctions which are the exact solution of “an atom in the field” boundary value problem the Hamiltonain of which...
This paper presents a simple technique for the calculation of the eigenfrequencies of biconical cavities using the overlapping domain decomposition method in combination with the collocation method, which converges rapidly with increasing number of collocation point pairs and offers a reasonable computation speed.
Modern electric power systems (EPSs) is a complex, dynamic, non-linear and stiff system. Adequate simulation of processes in EPSs is a non-trivial task. During its solution, in most cases, relay protection (RP) devices are modeled as the simple blocks which are compering input signal with a setting and sending a signal to the commutation equipment. The character and duration of the transients in real...
Different self-optimization methods are used in LTE network including load optimization, coverage and capacity optimization, dynamic correction of mobility parameters and automatic control of inter-cell interference. In existing mobile communication networks optimization of handover procedure is performed manually over time (days, weeks). Such approach is not satisfactory because the optimization...
We present the theoretical and experimental studies of the giant Goos-Hanchen effect and the effect of focusing of light beam in one-dimensional photonic crystals with spatial modulation of photonic band gap position. We show that the photonic crystal with slow exponentially modulated band gap applies the second-order phase modulation to the reflected light and can focus or defocus the light beam.
The advantages of the application of coupled biconical resonators for measurement of coaxial metal-dielectric structure in microwave range are demonstrated. The particularity of the approach is the use of one of coupled resonators as reference one and another for placing specimen that provides possibility to measure difference between corresponding resonance frequencies and the ratio of frequency...
Results of metal plate reflection coefficient estimation using experimental data obtained under variation of the distance between object and the aperture plane of measuring antenna in the form of a pyramidal horn with application of 3-probe meter and neural network for calibration are presented. Parametric spectral analysis in sliding windows was applied.
The frequency reuse mechanism and code division multiple access are not used in LTE networks that leads to simultaneous operating of multiple subscribers (or base stations if we are talking about downlink direction) in the same part of spectrum. It produces the high level of inter-cell interference in both directions. Before making the fine tuning of network parameter settings it is necessary to make...
A mobile network operators design LTE networks with help of a radio propagation models (Okumura-Hata, Walfisch-Ikegami, etc.). One of the most common model used in determining the radio coverage in LTE networks is COST 231 Hata. Tuning of the model is carried out using large number of measurement records to increase the accuracy of the path loss prediction. The path loss predictions of tuned model...
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