Journal of the Russian Universities. Radioelectronics / Известия высших учебных заведений России. Радиоэлектроника
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Синтез конструкции антенной решетки
Get PDFThe problem of linear antenna construction synthesize is first formulated and solved. Linear antenna consists of antenna array (AR) and power divider (PD). Linear omnidirectional AR with cosecant pattern is synthesized using partial-beam method. Beam-forming scheme for this antenna is based on two directional unequal splitters. The article proposes itera-tive method considering AR and beam-forming scheme mutual effect in terms of scattering matrix. Synthesis results demonstrate rapid convergence of the process and provide optimal pattern.Впервые поставлена и решена задача синтеза конструкции линейной антенны, состоящей из антенной решетки (АР) и делителя мощности (ДМ). Методом парциальных диаграмм направленности (ДН) синтезированы вертикальные всенаправленные в азимутальной плоскости АР с косекансной формой ДН в вертикальной плоскости. ДМ сигнала типа "дерево" сформирован на базе делителей на 2 направления. Предложен итерационный процесс формирования оптимального делителя с учетом взаимного влияния излучателей и ДМ на базе матриц рассеяния. Результаты синтеза показывают быструю сходимость процесса при оптимальных полученных параметрах системы АР–ДМ
НОВЫЙ ВОЛНОВОДНЫЙ МЕТОД ИЗМЕРЕНИЯ ПАРАМЕТРОВ ДИЭЛЕКТРИКОВ
Get PDFPerfect knowledge of dielectric parameters is necessary for its application in various devices. In spite of the whole range of measurement techniques, their practical implementation in the microwave frequency band runs into some difficulties. This article describes a new method for nonmagnetic dielectrics permittivity and loss tangent measurement in the microwave frequency band. A dielectric specimen slab is placed in the short-circuited waveguide section normal to its axis and fills the whole cross-section of the waveguide at approximately quarter wavelength from its short-circuited endpoint. By means of the vector network analyzer the waveguide section reflection factor is measured. Objective function is de-termined as difference between calculated and measured module and phase of the reflection factor. Specific code for ob-jective function calculation and its minimization is worked out. Minimization of this function by varying dielectric parameters makes it possible to find real values of these parameters. The method needs no de-embedding and can be used with non-calibrated waveguide-to-coax transitions. Also it is less sensitive to the noise component of reflected signal. The testing results show that new method’s error does not exceed 0.2 % for relative permittivity and 1% for dielectric loss tangent
АЛГОРИТМ ОЦЕНКИ КООРДИНАТ ОБЪЕКТОВ ДЛЯ СИСТЕМ МУЛЬТИЛАТЕРАЦИИ
Get PDFAt present, multilateration systems are becoming increasingly important in air traffic control. This is due to their significant advantages in compare with secondary surveillance radar complexes. This article solves the problem of synthesizing an algorithm for object location estimation for multilateration system operating in passive mode. The synthesized algorithm is a combination of a procedure, the result of which is a rough estimate of the observed object coordinates, and an iterative algorithm specifying the resulting solution. The rough estimate is the result of solving a linear system of equations. The iterative refinement procedure is based on the linearization of the observational equations and does not require a large number of iterations. The paper provides a comparative statistical analysis of the proposed algorithm and the known Bancroft algorithm. For an objective analysis of two algorithms, the paper derives the Cramer-Rao boundary for the correlation matrix of estimates of the observed object coordinates, which makes it possible to determine the potential accuracy of the solution of the problem. It is shown that both algorithms allow obtaining estimates, the accuracy of which is close to the potentially achievable accuracy of the object location estimate. In contrast to the Bancroft algorithm, the rough estimate of the object location is unambiguous. This virtue reduces the total amount of computations during the algorithm implementation and reduces the probability of anomalous errors
Предельные характеристики согласования приемных рамочных антенн с помощью нефостеровских цепей
Get PDFThe limiting characteristics of electrically small-sized loop antenna matching by means of non-Foster's negative inductance are studied. Various options for including negative inductance in frame antenna structure are considered. The analytical limit expression for the operating frequency band of the small-sized loop antenna with the inclusion of negative inductance in the gap of the conductor frame is obtained. It is shown that for practical implementation the most convenient is the scheme with the inclusion of negative inductance between the conducting plane and the free output of the frame. Such inclusion of negative inductance causes small loss in width of the working frequency band compared with the inclusion of this inductance in the gap of the frame conductive plane, but EMF induced in the frame is twice as large. An integral expression is obtained for the maximum band matching of the small-sized loop antenna with the inclusion of negative inductance in grounded output, the integral in which is calculated numerically for various small-sized loop antenna quality factor and ratios between resonant frequency of the frame and operating frequency range. The results obtained are similar to Fano-Yula restriction for passive matching chains
ПРОГРАММИРОВАНИЕ ДВУХБИТНОГО PIN-ДИОДА В СРЕДЕ SYNOPSYS SENTAURUS TCAD
Get PDFThe article is devoted to the modeling of a two-bit pin-diode. The possibility of programming opening time of the device based on the pin-diode is shown. The design consisting of a pin diode and two floating gates on the surface of i-region is considered. The addition of electrodes to the surface of the i-region makes it possible to regulate the concentration of electrons and holes within the larger limits in compare with the single-gate structure creating enriched and depleted are-as in the structure. Programming is carried out by applying the appropriate voltage to the control electrodes of the floating gates. It is shown that the charge generated on the floating gate changes characteristics of the i-region of the pin diode.The key elements of complex simulation of the two-gate pin diode are simulation of charge accumulation mechanism on the floating gate, simulation of pin-diode opening time and calibration of numerical model. Simulation is performed in Synopsys Sentaurus TCAD. Physical models describing traps and their parameters, particle tunneling, transport phenomena in dielectrics and amorphous films are used in simulation. As a result of modeling, the opening time dependences on size, floating gate location and floating gate charge magnitude are obtained.It is shown that the pin-diode 2-gate structures allow to change the opening time in a wider range than the single-gate ones. To program a large range of pin-diode opening times, it is 2 gate structure that is advisable to use. The obtained results indicate that it is possible to implement a two-bit programming pin-diode and expand its functionality
Выбор модуляционного формата и параметров сигнала спутникового высотомера
Get PDFSatellite altimeters play a key role in Earth remote sensing programs. To attain a centimeter accuracy level within the limited energy budget the altimeter probing signal should have a processing gain of the order of tens of thousands. Un-der such circumstances both of the angle modulation modes (LFM, BPSK) are equivalent as for their tactical performance. Preference of LFM in modern foreign devices is based on the tendency to reduce demands to digital processing operation speed by transferring wide-band processing to the analog receiver part. However, modern circuitry capabilities allow to implement digital processing of the signals with the bandwidth of hundreds MHz, giving thereby the way to involving BPSK signals which are not that susceptible to various drifts and external disturbances, do not require frequency modulation super-linearity, etc. In the paper both modulation formats are compared and recommendations are given on how to choose the structure and parameters of BPSK signal
ОПРЕДЕЛЕНИЕ ТОЛЩИНЫ УПРОЧНЕННОГО СЛОЯ МЕТАЛЛА МАГНИТНЫМ МЕТОДОМ
Get PDFThe routine method to control metal surface layer is Vickers hardness test method. The existing nondestructive testing methods are based on measuring induction density and other magnetic quantities in magnetizer core. This causes the method error and restricts the ability to determine the structure of the processed material. The paper provides theoretical and experimental investigation of the method for controlling the hardened axis layer parameters by analyzing characteristics of stray magnetic field of the axis magnetized local surface area before and after rouletting. A method is proposed for determining the hardened metal layer thickness of the rolling stock axis, based on measuring the parameters of the magnetized local area stray magnetic field before and after processing. To justify the proposed method, mathematical modeling of stray magnetic field of the axis local magnetized section is performed before and after processing. Inspection for the hardened metal layer is performed using magnetization of the axis local segment with electromagnet, followed by measuring the stray magnetic field strength. The maximum value of the horizontal magnetic force is determined, which is an informative parameter. A mathematical model is developed for the magnetized section magnetic field, the results of numerical and field experiments are presented. The discrepancy between the experimental data and the results of theoretical calculations is estimated. The method makes it possible to control the thickness of the hardened metal layer and the quality of the hardening of the rolling stock axis
Статистические характеристики оценки параметров сигнала по максимуму нормированного коррелятора
Get PDFIn this paper differences between Fisher Information Matrix (FIM) and inverse covariation matrix of normalized correlation estimations for white and colored noise are investigated. It’s shown that implementation of normalized correlation function estimation leads to modification of maximum likelihood estimation FIM elements, so in case of arbitrary energy affected parameter vector, variance of estimation by normalized correlation function maximization is not equal to Cramer–Rao lower bound. Statistical characteristics of joint Doppler stretch and delay estimation by maximization of normalized correlation function for signal with nuisance parameters are derived in this paper. It’s shown that normalized correlator is equal to wideband ambiguity function, but this method of estimation follows from Cauchy–Schwarz inequality without using energy conservation assumptions. Besides, it is proved that estimation of Doppler stretch and delay by normalized correlation function or WBAF of signal with random initial phase and gain is asymptotically unbiased and effective.Приводится подробное исследование дисперсии оценок произвольного вектора параметров сигнала по максимуму нормированного коррелятора (НК) для случая белого и окрашенного шума. Проведено сравнение с нижней границей Крамера–Рао (НГКР). Показано, что использование НК приводит к появлению поправок к элементам матрицы Фишера, полученным при анализе максимально правдоподобных оценок, и в общем случае дисперсии оценок энергетических параметров по максимуму НК будут отличаться от НГКР. В качестве конкретного приложения исследуются статистические характеристики оценки доплеровской деформации и задержки сигнала по максимуму НК при наличии неинформативных параметров. Показано, что НК по форме совпадает с известной широкополосной функцией неопределенности, при этом рецепт оценки выводится из неравенства Коши–Буняковского без обращения к закону сохранения энергии. Также показано, что оценка деформации и задержки при неизвестных начальной фазе и амплитуде сигнала из НК является асимптотически несмещенной и эффективной
Синхронизация, сбор и передача сигналов многоканальной распределенной сейсморазведочной антенны
Get PDFCreation of seismic antennas involves production of a system capable to provide synchronous analog-to- digital data signal conversion of all channels and to broadcast digitized signals to the central computing complex (CCC). The article considers a structure of data transmission system from a big number of sources for application in seismic antennas. Moreover, it provides possible ways of preprocessing equipment (PE) unit arrangement in separate hermetic blocks to facilitate their replacement. Besides, the options for PE unit structural and functional schemes are offered. Application of specific chips is explained. The review of the most widespread types of digital convertors is given and the optimal one is chosen for application in hydro acoustic complexes. The option of synchronization with the use of phase-locked loop PLL units is offered. Configuration of data transmission system with the use of Ethernet switchboard setting optimal data transmission protocol is considered.При создании сейсморазведочных антенн ставится задача по реализации системы, способной обеспечивать синхронное аналого-цифровое преобразование сигналов всех каналов и передавать оцифрованные сигналы в центральный вычислительный комплекс (ЦВК). Рассмотрена структура системы передачи информации от большого количества источников для применения в сейсморазведочной антенне. Приведена возможная реализация блоков аппаратуры предварительной обработки (АПО) в отдельных гермоблоках для упрощения процесса их замены. Предложены варианты структурной и функциональной схем блоков АПО. Обосновано применение конкретной элементной базы. Проведен обзор наиболее распространенных видов аналого-цифровых преобразователей и выбран оптимальный для применения в гидроакустических комплексах. Предложен вариант синхронизации с применением блоков фазовой автоподстройки частоты. Рассмотрено построение системы передачи с использованием коммутатора Ethernet с выбором оптимального протокола для передачи информации в ЦВК