Digital Antenna Research Articles

Особенности структурного синтеза алгоритмов обработки радиолокационной информации при многочастотном наблюдении

Setting and solving the problem of structural synthesis of the algorithm for detecting and measuring parameters of mobile objects against the background of correlated interference and noise in multi-frequency radar surveillance systems based on multibeam digital antenna arrays are considered. The processing algorithm is synthesized under the assumption of Gaussian observation statistics with separate spatial and temporal characteristics of signals and interference. As part of the study, a phenomenological model of the radar situation was developed, adequate to the formation of observations in multi-frequency space-time signal processing systems against the background of correlated interference and noise. On its basis, a structure of an optimal, in terms of Bayesian quality criteria, algorithm for detecting a multi-part signal at the outputs of multipath digital antenna arrays is obtained. On the basis of the adaptive Bayesian approach, ways of solving the problem of detecting and measuring parameters of mobile objects in conditions of multi-frequency observations with parametric a priori uncertainty about interference characteristics are determined. Recommendations on selection of adaptive algorithms for radar information processing in case of non-stationary observations are given. The results of structural synthesis make it possible to present processing in the form of a multichannel system in space, time and radial speed. Sufficient statistics on the set of radiation frequencies are accumulated. This view opens up a wide range of possibilities for using parallel computing systems. It is shown that the obtained algorithms can serve as the basis for detecting the beginning of maneuvering of an observation object at the stage of primary processing of radar information.

Adaptive digital antenna array signal processing algorithm based on LDL decomposition

Two algorithms for inverting correlation matrices of digital antenna array signals are compared: LDL decomposition and the fringing method. The idea of comparing algorithms was to take into account the limitations on the length of the input data mantissa in the process of space-time processing using FPGAs. It has been found that rounding errors in the signal processing process in FPGAs can lead to the destruction of the directivity pattern. This is due to the fact that when implementing various algorithms for matrix inversion, the distribution of errors in the channels becomes interconnected. This means that when implementing adaptive antenna arrays on FPGAs, it is necessary to carefully choose the length of the mantissa and the conversion algorithm. In this regard, an algorithm for signal processing in an adaptive antenna array is proposed, its difference from the known ones is that when implemented on FPGAs, floating-point arithmetic of limited mantissa bit is used. When comparing two computationally efficient matrix inversion algorithms (the LDL method and the fringing method), the LDL method has higher stability. It was found that with an increase in the rank of the correlation matrix, the effect of rounding errors will be stronger. In this regard, it is necessary to determine in advance at what ratio of power sources and internal noise it is planned to use an adaptive processor.

Semi-Automatic Design of Dual-Band End-Fed Antennas for Digital Antenna Arrays

Introduction. The topic of implementing a dual-band mode of operation for director dipole antennas is represented by a wide range of works, almost all of which are dedicated to studying the properties of a classic dipole. However, the issue of end excitation of radiators for dual-band director antennas remains open. The development of such radiators requires a deep analysis both from the point of view of developing mathematical and electrodynamics models, which corresponds to the tactical and technical requirements of modern digital antenna arrays.Aim. To substantiate a procedure for determining the initial appearance of a dual-band antenna exciter from the standpoint of the systems approach to the design of antenna elements and nodes. This procedure is suitable for a semi-automated design of more complex antenna systems.Materials and methods. As part of the research, the input impedance of a dual-band system consisting of two active radiators and two passive directors was determined using the method of induced electromotive forces (EMF). Models of dual-band director radiators were developed using the CST Studio Suite 2021 full-wave electromagnetic simulation.Results. The results of developing procedures for a semi-automatic design of antennas with a dual-band function of input impedance are presented. Following a comparative analysis, approaches to implementing the printed layout of an antenna comprising standard radio engineering components, which imply serial production, are proposed.Conclusion. The proposed models can be used when designing director, turnstile, and cardioid antennas, as well as antenna arrays. These designs are analogous to antennas based on a classic central excited dipole.

Digital antenna array based on programmable logic integrated circuits for mobile radio networks

Currently, there is a need to develop new technical solutions for antenna systems for central (base) stations of mobile radio networks, which not only have improved electrical characteristics, but also allow them to adjust from intentional and unintended interference, while providing a reliable communication channel between several correspondents. The purpose of the work is to develop methods for constructing digital antenna arrays with adaptive DN control for VHF mobile radio networks. The presented solution of the ring car allows you to form the DN in the specified directions, to work in multipath mode, as well as the proposed solutions of ring cars can be used both in the center (base) stations of mobile radio communication systems and on mobile objects operating, including in the relay mode.

The main directions of enhancement of digital antenna arrays

The development of modern radio electronic systems causes an increase in the requirements for the parameters of antenna devices (AU) and causes the transition from previously used mirror antennas and passive phased array antennas (FAA) to active FAA (AFAA), the considerable advantage of which is a significant reduction in energy losses of transmitted and received signals by reducing the distance of the low-noise amplifier input and output of power amplifier to the antenna element. Further development of the AU is the transition from AFAA with analog beamforming to digital antenna arrays (DAR) with digital beamforming, the advantages of which are due to the possibility of forming multibeam receiving and transmitting radiation patterns with independent control of the direction and shape of the beams, as well as the possibility of flexible change of operating modes. The use of a DAR with two-dimensional electronic scanning provides a significant increase in the efficiency of radio-electronic systems. Thus, their use in radar provides a gain in the efficiency of using the time, energy, frequency and spatial resources of radar with CAR up to 13 times compared with radar with passive FAA and AFAA with one-dimensional scanning. The disadvantages of the DAR are the high cost and increased energy consumption due to the installation of active elements in each transceiver channel, as well as the long time required to create new products, associated with a large amount of software and a complex structure for building a CAR. To overcome these disadvantages, manufacturers of antenna arrays and developers of the radio-electronic element base are creating new technical solutions. The main directions of development of technologies for the production of DAR functional devices that reduce the cost and reduce the time needed to create new products are shown: the development of common modules that allow you to create scalable DAR, increasing the integration of microwave monolithic integrated circuits with the placement of the maximum number of transceiver channels on one chip, increasing the integration of ASIC, including ADCs, DACs and digital signal processing devices, increasing the clock frequencies of digital functional nodes, as well as the development of circuit solutions for building nodes with low energy consumption.

Method for measuring radiation patterns of digital antenna arrays

Formulation of the problem. The Digital Beamforming Antenna Arrays (DBAA) are widely used as the directional antennas in radio systems today. However, such arrays typically do not have a radiofrequency output. Consequently, the standard methods for measuring the Radiation Patterns (RP), based on the transmitting of a monochromatic probing signals, reception of the signals in the far field, as well as measuring the output power of the antenna array, cannot be used to measure the RP of the DBAA. The method considered in this work involves the transmitting a probing signal modulated by a pseudonoise sequence and processing the DBAA output signal at the zero intermediate frequency (base-band) using a matched filter or a correlator. Target. A method for measuring the radiation pattern of the DBAA is considered, based on the correlation processing of its output signal. Results. The paper presents a description of the setup for measuring the DBAA RP, as well as a mathematical explanation of the measurement procedure. It is shown that the accuracy of the RP measurement depends on the Signal-to-Noise Ratio (SNR) at the outputs of the receivers of the DBAA channels, and the number of array channels and the number of symbols of the pseudonoise sequence used for the modulation of the radiated signal. The error in the RP measurement decreases by 3 dB each time as the number of the DBAA channels or the number of symbols of the pseudonoise sequence used in the measurements is doubled. This result is confirmed by simulation the measurement of RP of the eight- and sixteen-channel linear DBAA using pseudo-noise sequences of maximum length (M-sequences) with a number of symbols equal to 1023 and 2047. Practical significance. The proposed method does not require the usage of the up-converter to convert the base-band DBAA output signal from the base-band to a carrier frequency, and it also does not require the usage of a power meter for measurement the analog signal at the output of this converter.

Computer‐aided experimental studies for adaptive beamforming algorithms and array processing in engineering education

AbstractSmart antenna and digital antenna systems are considered as a crucial technology for current and future communication systems supporting 5G/6G and nonterrestrial‐networks communications. Based on the information of the received signal/s, smart antenna systems toward the radiation pattern to the desired direction/s. This technique is known as adaptive beamforming. The theories and the applications of adaptive beamforming are taught in engineering educational courses. This paper proposes a set of real‐time interactive experiments for adaptive beamforming algorithms in antenna array processing subject. The proposed experiments can be performed with the computer‐aided experimental studies tool prepared in the MATLAB® environment. The users can easily make comparisons and can perform trade‐offs between different types of adaptive beamforming algorithms, scenarios, and antenna architecture. This is used as a teaching tool for a graduate course on adaptive beamforming algorithms.

Electrodynamic modeling of a four-channel antenna with an operating frequency band of octave

The actual problem of electrodynamic modeling of a four-channel antenna with an octave operating frequency range has been considered. The results of numerical electrodynamic modeling of a four-channel antenna have been presented. The considered antenna with an octave operating frequency range is a rectangular curtain comprising four independent non-equidistant channels. Numerical electrodynamic modeling of a four-channel antenna has been carried out in the ANSYS HFSS software package, with the convergence parameter DeltaS = 0.01. As a result of the simulation, the frequency characteristics of each channel have been obtained: VSWR, gain, reflection coefficient, directional pattern. The antenna provides a scanning angle as part of an ultra-wideband digital antenna array of at least ±30° in azimuth and from 0° to 60° in elevation. The gain of the antenna channels in the operating frequency range is not lower than 6 dB. According to the simulation results, the VSWR of each channel of the antenna in the operating frequency range does not exceed 2.55. To minimize the influence of mutual coupling of channels on the antenna characteristics, the distance from the phase centers of the curtain emitters to other elements of the ultra-wideband digital antenna array should be at least a wavelength in free space at the lower frequency of the operating frequency range. It has been shown that the considered four-channel antenna provides an octave operating frequency band and can be used as part of an ultra-wideband digital antenna array for direction finding of radiation sources.

Spatial Selection-Based Intelligent N-OFDM Signal Processing in Wireless Communication Systems

The method of joint processing of pulses and OFDM (N-OFDM) signals is proposed. The corresponding analytical relations for the lower Cramer-Rao boundary on the dispersion of OFDM (N-OFDM) signals amplitude ratings in the presence of sources of pulsed radiation are obtained. Using mathematical modeling properties and limitations of the demodulation method of OFDM (N-OFDM) signals in the background of impulse signals in the integrated radar and telecommunication systems are established. It is determined that the use of the angular distance between the pulsed and OFDM signals sources at a value that is not less than 0.75 widths of the secondary beam of the digital antenna array pattern does not affect the accuracy of the OFDM signal amplitudes. The same applies to the active interferences.

Phase noise of signal generators with multichannel digital synthesizers

Wide use of a direct digital synthesizer (DDS) and digital to analog converters (DAC) in digital antenna arrays permits for fast modulation parameters variations and beam positioning, and also improves the quality of beam forming due to high accuracy of signal generation. However, any systematic and random phase deviations of array channels not only lead to distortion of radiation pattern but also cause deterioration of signal processing at receiver end. Phase noise is one of critical parameters of such systems. Traditional theory and empirical methods assumes small or zero phase deviation of phase of channel output signal when combining these signals. We have proposed the model in which coupling of AM and PM noise persists for any arbitrary phase deviation of channels in multistage circuits comprising multichannel digital synthesizers. Absolute phase noise measurements of combined DACs outputs for zero phase offset and antiphase modes with two values of DAC output signal amplitude difference permit for estimation of residual phase noise of DAC and clock receiving and distribution circuitry and demonstrate good compliance of results of calculation.

ANALYSIS OF TELEVISION SIGNAL BOOSTERS USING DIGITAL TELEVISION BOOSTERS AND ANTENNA

A digital antenna is a device used to capture digital signals. Digital television broadcasts are capable of transmitting better reception quality image signals on the television screen than analog broadcasts. Using an antenna without a booster causes less than optimal reception for several stations that are quite far from the receiving antenna. The television antenna booster functions as an amplifier for signal losses received from the antenna via coaxial cable. The signal that enters the antenna through the cable is a very weak RF signal. The booster itself works as an RF signal amplifier and also acts as a frequency selector used by the television receiver (VHF or UHF). This research aims to analyze the comparison of the performance of two antenna boosters, namely the TOYOSAKI Booster and MATRIX Booster, using digital antennas, namely the TOYOSAKI, MATTRIX and TAFFWARE antennas, to find a comparison of which antenna and booster are the best. This research uses the SINPO method, namely a number code to assess signal strength, interference, atmospheric noise, propagation conditions, and general impression of reception. Ratings are made with numbers ranging from 5 (very good) to 1 (very bad). The research results show that the quality of the images produced by the TOYOSAKI and MATRIX antennas is better using the MATRIX Booster than using the TOYOSAKI Booster. Meanwhile, for the TAFFWARE antenna, it is better to use a TOYOSAKI Booster than to use a MATRIX.

Direction finding of sources of electromagnetic radiation signals by digital antenna arrays with invariant phase center

Direction finding of sources of electromagnetic radiation signals by digital antenna arrays with invariant phase center

Способ построения двухэлементной цифровой антенной решетки для оценки угловых координат радиосигналов со сверхразрешением с повышенной точностью на основе нижней границы Крамер-Рао

In the paper an effective method for optimal placement of directional antenna elements for digital spatial signal estimation is discussed. The digital antenna array evaluates spatial coordinates with the subsequent beamforming. However, as it is well known, the relative position of antenna elements, their number and the shape of the radiation pattern have a significant impact on the quality of the spatial pseudospectrum. The paper uses the previously obtained expression for estimating the Cramer-Rao lower bound to reduce the number of antenna elements without losing the accuracy of direction-of-arrival estimation of the signals. For example, a two-element array is obtained. The elements have a flat-top radiation pattern. It is shown that the accuracy of the MUSIC method in the obtained array is higher or comparable to the array composed of three elements.

ПРИНЦИП СУБЪЕКТИВНОЙ ИЗБЫТОЧНОСТИ И МЕТОД СЖАТИЯ ДАННЫХ, ПОЛУЧАЕМЫХ ОТ ЦИФРОВЫХ АНТЕННЫХ РЕШЕТОК

The problem of limiting the capacity of the diagram-forming circuit of the digital antenna array is considered, due to the capabilities of existing communication lines with serial data transmission from the receiving channels to the computer. This problem limits the possibilities of implementing various methods of signal processing in digital antenna arrays. The subject of the study is the possibility of increasing the capacity of the diagram-forming circuit of the digital antenna array due to software compression of radar data. The purpose of the work is to create a scientific and methodological apparatus that will increase the capcity of the diagram-forming scheme by using the principle of subjective redundancy in relation to radar data processing tasks. The results of the work include: justification and formulation of the principle of subjective redundancy of radar data and the method of compression of radar data, as well as the results of numerical studies confirming the operability of the proposed scientific and methodological apparatus. The principle of subjective redundancy is based on the independence of the separation of signal processing processes in the spatial and temporal domains when receiving a single echo signal, and in the case of receiving several echo signals, on the principle of superposition of fields from various sources in the far antenna zone. The method of radar data compression is based on the principle of subjective redundancy of radar data and differs from the known iterative procedure for approximating the matrix of complex samples in the form of a superposition of products of one-dimensional cosine spectra. It is shown that the application of the radar data compression method makes it possible to increase the transmission capacity of the digital antenna array transmission lines several times.

Застосування аналого-цифрових перетворювачів для підвищення ефективності цифрових антенних решіток

Застосування аналого-цифрових перетворювачів для підвищення ефективності цифрових антенних решіток

A Versatile Digital Antenna Array Transceiving System With Online Self-Calibration

A Versatile Digital Antenna Array Transceiving System With Online Self-Calibration

Sensing-Assisted Beam Tracking for mmWave V2I Communications with Analog, Hybrid, and Digital Antenna Architectures

Sensing-Assisted Beam Tracking for mmWave V2I Communications with Analog, Hybrid, and Digital Antenna Architectures

Ultrasound tomography based on the coefficient inverse problem as a way to combat structural noise

The paper proposes to use the ultrasound tomography method based on the solution of the inverse coefficient problem to reduce the level of structural noise. Mathematical models used in ultrasonic tomogra-phy well describe such physical effects as refraction, diffraction and redispersion effects. It is logical to ex-pect that reconstruction of the internal structure of metallic samples using ultrasound tomography will be more efficient compared to digital antenna focusing (DAF) techniques. Due to the nonlinearity of the inverse problem of ultrasound tomography, an iterative MultiStage method is used to ensure convergence to the glob-al minima of the non-convexity functional. The paper presents the results of numerical experiments to restore the image of the internal structure of the welded joint, which may contain lateral cylindrical holes and crack models. The region of the welded metal is represented in the form of sections constructed according to the principle of Voronoi diagrams. In each section the velocity is constant and its value is randomly distributed. In the model adopted in the paper, the structural noise is formed due to multiple scattering at the boundaries of sections with different sound velocity. It was assumed that the antenna array is located on the outer surface of the control object of known thickness. The results obtained show that the tomographic method allows us to determine the shape and speed of sound in low-contrast reflectors, for which the CFA method is ineffective.

Development of the Phaseless Calibration Algorithm for a Digital Antenna Array

In this paper, we will discuss a calibration algorithm for a digital antenna array that diagnoses its real performance. It can be applied at such stages of the antenna system life cycle as design, tuning, and especially maintenance. A calibration implementation using a scalar method for a multi-beam digital antenna array is proposed and investigated. On-the-fly calibration ensures a continuous improvement in beam pointing accuracy by reducing internal errors in the receiving (transmitting) channels. The purpose of the study is to experimentally examine the capabilities of digital beamforming to increase the angle-of-arrival estimation accuracy. A simulation model of the receiving antenna was created in an anechoic chamber with a planar antenna positioner. The possibility of precise estimation of the direction of arrival using the digital beamforming with electronic scanning was demonstrated. The proposed simulation model made it possible to observe the convergence of the antenna array calibration process using the proposed method for various errors in the signal paths, as well as different signal-to-noise ratios. It has been proven that even under adverse conditions early in the calibration algorithm, the phase error detection converges with high accuracy, and its value decreases uniformly even to the fractions of an angular degree.

Статистическая модель высоконаправленной цифровой антенной решетки пространственно-корреляционным методом обработки сигналов

The article presents a statistical model of a digital antenna array with a spatial correlation method of signal processing. The model is obtained on the basis of the Neumann-Pearson criterion for the conditions of a stationary Gaussian distribution of the output process in spatial correlation signal processing. This model makes it possible to numerically evaluate the probabilistic characteristics of radar signal detection for various orders of nonlinear processing under the influence of natural radio interference and can be recommended for the study and optimization of the construction of the antenna array aperture with spatial correlation signal processing, providing a given spatial noise immunity of radio engineering systems.