Modern Radar Research Articles

An Implementation of Interactive Application for the Synthesis of Communication Systems with Antenna Arrays

Introduction. Modern radar and communications systems contain phased array antennas. One of the synthesis problems of such systems is the formulation of requirements for components, modules and units which are comprised in it. To solve this problem, one needs to build a coverage area and to analyze an impact of characteristics of its parts. The quality of analysis and synthesis of such complex systems can be enhanced by use of interactive data visualization, which requires a fairly quick calculation of characteristics.Aim. Development of an interactive application for increasing the synthesis capabilities of communication systems containing antenna arrays and for improving the characteristics of systems of interest.Materials and methods. To accelerate the calculation of radiation patterns, the antenna array pattern in a form suitable for the fast Fourier transform algorithm was used. To find the required amplitude-phase distributions, Kotelnikov series expansion and genetic algorithm were used.Results. In the developed application, amplitude-phase distribution, directivity pattern of a linear equidistant array and coverage area were displayed. An interactive change of the amplitude-phase distribution at radiation elements and synthesized radiation patterns in given directions were possible. With introduction of changes to the radiation pattern, the amplitude-phase distribution and the array radiation pattern itself changed in directions other than the specified one. The coverage area was rebuilt when any of the characteristics changes. If necessary, the coverage area display could be turned off. The paper provides an example of using the application in the synthesis of a communication system with an aircraft.Conclusion. The use of the developed application allows one to extend the capabilities and significantly reduce the analysis and synthesis time of the communication secondary radar systems with antenna arrays too. Besides, the application is used for training specialists for industry enterprises.

Machine-learning-assisted optimization and its application to antenna designs: Opportunities and challenges

With the rapid development of modern wireless communications and radar, antennas and arrays are becoming more complex, therein having, e.g., more degrees of design freedom, integration and fabrication constraints and design objectives. While full-wave electromagnetic simulation can be very accurate and therefore essential to the design process, it is also very time consuming, which leads to many challenges for antenna design, optimization and sensitivity analysis (SA). Recently, machine-learning-assisted optimization (MLAO) has been widely introduced to accelerate the design process of antennas and arrays. Machine learning (ML) methods, including Gaussian process regression, support vector machine (SVM) and artificial neural networks (ANNs), have been applied to build surrogate models of antennas to achieve fast response prediction. With the help of these ML methods, various MLAO algorithms have been proposed for different applications. A comprehensive survey of recent advances in ML methods for antenna modeling is first presented. Then, algorithms for ML-assisted antenna design, including optimization and SA, are reviewed. Finally, some challenges facing future MLAO for antenna design are discussed.

Polarization Manipulated Fourier Domain Mode-Locked Optoelectronic Oscillator

We report a polarization manipulated Fourier domain mode-locked optoelectronic oscillator (FDML-OEO) using a polarization modulator (PolM). Frequency and bandwidth doubling linearly chirped microwave waveforms (LCMWs) are generated from a PolM-based FDML-OEO. The multiplying operation is capable of increasing the frequency and bandwidth of LCMWs, which doubles the time-bandwidth product of the LCMWs and makes it possible to increase the center frequency of the LCMWs beyond the bandwidth of the optical modulator. Moreover, by simply adding the other laser diode, it is also possible to generate a dual-chirp LCMW. The polarization manipulated of two optical signals avoids the undesired beating signals from optical carriers. Thus, an electrical bandpass filter which is essential in previous work is no longer required. To the best of our knowledge, this is the first time that polarization manipulation is used in FDML-OEO, which can further satisfy the demands of modern radars in terms of improved range-Doppler resolution, higher carrier frequency, and larger bandwidth.

ANALYSIS OF POSSIBILITIES OF PROVIDING OF NECESSARY EXACTNESS OF MEASURING OF SPATIAL COORDINATES OF AIR OBJECTS IN THE RADIO-LOCATION STATION OF ACCOMPANIMENT WITH PHASE AERIAL BY A GRATE

Modern Phased-Array Antenna (PAA) radars are an effective mean of aerial reconnaissance and provide radar information on aerial objects in a complex environment. The subject of the article is the influence of the inhomogeneities of the troposphere and the earth’s surface on the decrease in the accuracy of measurement of angular coordinates and altitude of air objects in radars with PAA. The purpose of the article is to numerically estimate the possible values of the root mean square error of measuring the angular coordinates and the height of air objects due to the influence of fluctuations of the phase edge of the radar wave. Task : analysis of possible mechanisms of origin and statistical characteristics of correlated phase fluctuations of a radio signal for a model of a signal with random amplitude and initial phase. Methods used : methods of probability theory and mathematical statistics. The following results were obtained . The estimation technique is developed and possible values of the mean-square errors of measurement of angular coordinates and altitude of air objects are obtained, which are caused by the influence of radar signal phase wave front fluctuations for the three-coordinate PAA radar of centimeter range. The above calculation method allows to carry out the numerical estimation of errors of measurement of angular coordinates and object height. Conclusions . This technique can be practically used in assessing the effect of real conditions of propagation and reflection of radar signal on the reduction of the capabilities of modern radars with PAA to perform tasks on purpose.

Analysis of the height difference of the zero isotherm according to two temperature profilers

One of the main indicators characterizing the quality of meteorological support of flights is the justifiability of aviation weather forecasts and forecasts of dangerous weather phenomena. For the detection and prediction of dangerous meteorological weather phenomena are currently used very advanced systems, which include meteorological radar stations near the airfield zone. The reliability of the forecast of such dangerous weather events as icing, thunderstorms, hail, squally wind according to the information from the meteorological radar stations of the near airfield zone significantly depends on the data on the height of the zero isotherm. The correctness of the entered values of the zero isotherm position directly affects the probability of false alarms, and, consequently, the degree of justification of weather forecasts and forecasts of dangerous weather events. The source of information about the position of the zero isotherm can serve as radiosonding data of the atmosphere. However, the data of aerological radiosonding of the atmosphere are not operational. In addition, at present, obsolete systems are used on Roshydromet aerological network in addition to fairly modern aerological radar systems. This, in conjunction with the sufficiently low cost of the network of aerological stations on the territory of the Russian Federation does not allow the operational use of radiosonding data to determine the height of the zero isotherm at a particular airport. An alternative source of information about the position of the zero isotherm for solving the problems of meteorological location are temperature profilers. Temperature Profiler refers to the remote means of measuring the parameters of the atmosphere, and the principle of its operation is based on the methods of radiometry. Use the temperature of a caliper can be operatively obtain information about the temperature profile at the airport and, therefore, it can be a source for weather radar data on the zero isotherme, and isotherme -22°C, which is also used to identify hazardous weather phenomena. In this paper, the spatial variability of the zero isotherm position is analyzed according to the data of two temperature profilers. As a result of experimental studies, it was determined that within a radius of about 10 kilometers from the installation site of the Profiler, the measured temperature profiles remain virtually unchanged. This result can be used in the development of methods of placement of meteorological support for flights at the airport. Of practical interest are similar studies for airfields located in the mountainous, coastal and other geographical regions of Russia.

Unveiling and Dedication of IEEE Radar Historic Milestone

An article in the September 2019 issue of the AES Magazine described the background of the IEEE Historic Milestone to mark the invention and first demonstration of the radar by the German inventor Christian H€ulsmeyer [1]. On 17 May 1904, H€ulsmeyer arranged a demonstration of his invention in K€oln (Cologne), Germany, which was reported in the K€olner Tageblatt and K€olnischer Zeitung newspapers the following day. This device was conceived as a means of detecting ship targets, even under conditions of poor visibility, and hence preventing collisions. By the standards of modern radar, it was very crude, using a spark-gap transmitter and a coherer-type receiver. He patented his invention both in Germany and in the U.K. On 19 October 2019, the invention was formally marked as an IEEE Historic Milestone. This article describes the event and the various contributions that came together to make a very special day for IEEE AES and for the worldwide radar community.

Implementation of MOIDS Algorithm for Optimal Parameter Selection of SFPT for Modern Radars

Modern radars require signals of the large frequency range to attain relatively greater range resolution. Frequency stepping is the technique to convert the narrowband signal, i.e., a train of pulses into a wideband signal to achieve high accuracy in range resolution measurements. Due to the cause of constant step in frequency of successive pulses, grating lobes appeared when the period of pulse multiplied by step in frequency exceeds unity as is needed in modern radars. Hence to achieve the best resolution, grating lobes height, sidelobes level, and mainlobe width have to be minimum. In this paper an attempt has been made to diminish grating lobes, minimize sidelobes and reduce mainlobe width using MOIDSA to find the parameters of Stepped Frequency Pulse Train (SFPT) mechanism. The compromise between various lobes is obtained by using three dimensional Pareto fronts for different ranges of SFPT parameters.

Semantic Segmentation on 3D Occupancy Grids for Automotive Radar

Radar sensors have great advantages over other sensors in estimating the motion states of moving objects, because they detect velocity components within one measurement cycle. Moreover, numerous successes have already been achieved regarding the classification of such objects. However, the advantage of instantaneous velocity measurement is lost when detecting static objects, so that their classification is much more demanding. In this paper, we use semantic segmentation networks to distinguish between frequently occurring infrastructure objects. The resulting semantic grids provide a location-based classification of the vehicle environment. Since even modern radars have a significantly poorer angular resolution than lidars, the relatively thin radar point cloud is accumulated in advance and transformed into 2D or 3D grids that act as network inputs. Occupancy grids are particularly advantageous here, since they calculate not only the obstacles but also the free spaces. With suitable parameter selection, which is very challenging due to the complexity of radar measurement, the resulting grids allow for good association with camera images. Finally, in order to evaluate possible advantages of 3D grids as network input with respect to the segmentation result, we created and evaluated a simulation dataset and two different real-world datasets in car parks and on motorways. As a result, Jaccard coefficients between 81% and 88% were achieved, depending on the dataset. It was also found that 3D input images lead to improvements in the car park dataset.

REAL CONDITION AND PROSPECTS OF DEVELOPMENT OF THE RADAR STATIONS OF THE COUNTER BATTERY FIGHTINGV

Fighting in the Donbas, which has been going on for more than five years, shows that a skillful counter-battery fight is an important factor in achieving success in wars of this kind. Especially in conditions where for the known reasons the use of combat aviation is minimized. With the development of technical warfare, the task of servicing the counter-battery fight began to rely on radar stations (radar) to reconnaissance the positions of artillery, which in modern terms are called counter-battery radar. The principle of counter-battery radar is based on the detection of a target (artillery shell, mortar mine or rocket) in flight at an earlier stage and making several measurements of the coordinates of the current position of the ammunition. According to these data, the trajectory of the projectile's flight is calculated and, on the basis of its prolongation and extrapolation of measurements, the probable coordinates of the artillery, as well as the places of ammunition falling, are determined. In addition, the technical capabilities of radars of this class allow you to recognize the types and caliber of artillery systems, as well as to adjust the fire of your artillery. The main advantages of these radars are:  mobility (transportability);  inspection of large tracts of terrain over long distances;  the ability to obtain target's data in near real-time;  independence from time of day and weather conditions;  relatively high fighting efficiency. The purpose of the article is to determine the leading role and place of the counter-battery radar among other artillery instrumental reconnaissance tools, to compare the combat capabilities of modern counter-battery radars, armed with Ukrainian troops and some leading countries (USA, China, Russia), and are being developed and tested in Ukraine. The method of achieving this goal is a comparative analysis of the features of construction and combat capabilities of modern models of counter-battery radar in Ukraine and in other countries. As a result of the conducted analysis, the directions of further improvement of the radar armament, increasing the capabilities of existing and promising counter-battery radar samples were determined.

An Overview of Cognitive Radar: Past, Present, and Future

Modern radar systems face numerous challenges due to requirements of robust, high performance across multiple missions and multiple functions in the face of dynamically changing environments. Cognitive radar has emerged over the past 15 years through synergy of cybernetics, waveform diversity, and knowledge-aided signal processing as a new vision for the future of radar systems that can address these challenges. This article provides an overview of the historical context and mechanisms for cognitive processing in engineering systems, which have driven an evolution in the definition, analysis, and design of cognitive radar. A survey of cognitive radar research trends is given to provide insight on applications and techniques, while technical and practical challenges to future progress are discussed.

Covariance‐free non‐homogeneity STAP detector in compound Gaussian clutter based on robust statistics

Space-time adaptive processing (STAP) detects targets by computing adaptive weight vectors for each cell under test using its covariance matrix, as estimated from surrounding secondary cells. In this study, the non-homogeneity detector (NHD) excludes the anomalous secondary cells that adversely affect the detection performance. The existing robust NHDs require estimating the covariance matrix of each secondary cell, which hinders their implementation in modern radars with large-dimensional range cells. In this study, the authors propose a new low-complexity NHD that is suitable for highly correlated clutter environments with both Gaussian and non-Gaussian heavy-tailed distributions. The proposed detector, which is based on the projection depth function from the field of robust statistics, features a non-parametric and covariance-free test statistic. As a result, its computational complexity is much lower than that of current NHDs, such as the widely used normalised adaptive matched filter (NAMF) detector, especially for large-dimensional range cells. In Monte Carlo simulations with different clutter distributions and radar system configurations, the proposed detector shows comparable performance to that of NAMF. The low complexity and robust performance of the new detector make it particularly attractive for real-time applications.

Soft‐decision schemes for radar estimation of elevation at low grazing angles

In modern radars, the problem of estimating elevation angle at low grazing angles is typically solved using super-resolution techniques. These techniques often require one to provide an estimate of the number of waveforms impinging the array, which one can accomplish using model selection techniques. In this study, the authors investigate the performance of an alternative approach, based on the Bayesian-like model averaging. The Bayesian approach exploits the fact that the parameters of the model related to multipath signals are nuisance ones, which allows one to avoid the estimation of the number of waveforms and improves estimation performance. The method is introduced for the classical conditional maximum-likelihood estimator and extended to its, recently proposed, robustified version. The authors find, however, that the robustified estimator includes its own soft-decision mechanism and benefits from the averaging only for low levels of model uncertainty.

Retrospective Review of Perfect Ternary Sequences and Their Generators

Introduction. Perfect polyphase unimodular sequences, i. e. sequences with ideal periodic autocorrelation and single amplitude of symbols are widely used in modern radio communications and radar. A special place among them is occupied by perfect ternary sequences (PTSs) with elements {–1, 0, 1}. In fact, these are binary sequences with the alphabet {–1, 1}, but with zero symbols in some positions. It is known that PTSs are quite numerous and their length in comparison with perfect binary sequences is not limited from above. The charge for this is a peak factor greater than one, which causes energy losses in the receiver. A large number of research papers and books are devoted to the design of PTSs and the study of their properties. In particular, the handbook on sequence design by Fan and Darnell (1996) which provides an overview of the then known PTS families has become widely famous. However, over the past two decades, numerous new PTS families were discovered, some theorems on their existence were obtained, and connections were established between them and circulant weighing matrices. Therefore, there is a need for a new review of existing PTSs.Objective. The article is devoted to a retrospective review of existing PTSs and their generation devices.Materials and methods. Considered and analyzed domestic and foreign sources of information (books, journal papers, conference proceedings, patents).Results. Along with solving an informational bibliographic problem, the review shows the relationship between PTSs obtained at different times, their connection with circulant weighing matrices, and also describes the block diagrams of generators of some PTS families.Conclusion. A brief retrospective review of PTSs for their almost 60 years history is presented and the generators of some PTS families are considered. The results of the study are relevant for use in modern radio communications and radar systems and in particular, in CW and LPI radars.

A Design of Ultra-low Phase Noise Frequency Source Based on High Phase Detection Frequency

This paper introduces a design of ultra-low phase noise frequency source based on high phase detection frequency. Frequency source is a very important part of modern electronic system. Radar, communication, space technology and so on are inseparable from frequency source. Its performance index directly affects the whole electronic system, and phase noise is one of the most important indicators. In this paper, the scheme of phase-locked technology with high phase detection is mainly used,the phase noise is better than -116dBc/Hz@1kHz, -120dBc/Hz@10kHz, -121dBc/Hz@100kHz when the output frequency is 4.5GHz. The technology of high phase discrimination and low phase noise frequency synthesis in this paper can also be extended to higher and more special frequency bands. It provides a solution of ultra-low phase noise for frequency sources of modern radar, electronic jamming and countermeasure systems.

Research on modern radar emitter modelling technique under complex electromagnetic environment

Since many modern multi-functional radars emitting dense complex signals are applied in the complex electromagnetic environment, it is challenge to classify and identify the radar emitters in the electronic reconnaissance field. In order to classify and identify radar emitters accurately and rapidly, a kind of standard adaptive extended radar emitter modelling structure and the complete process of obtaining radar emitter model parameters are proposed in this study. The simulation analysis results show that the proposed standard modelling structure and complete process can rapidly realise the accurate classification of many multi-functional radar emitters; hence can further benefit to accurate identification of emitters.

Dynamic heartbeat detection algorithm based on RBFNN

The operational environment faced by modern radars is becoming increasingly complex. The timely detection of the failure of a node and the adoption of countermeasures to ensure the stable operation of the system have become the focus of radar network management. In this study, based on traditional heartbeat detection algorithm, we use a radial-basis neural network model to predict the timeout value. Therefore, a neural network heartbeat detection algorithm is proposed, which is used to detect the failure of the combat platform. The experimental results show that the proposed algorithm can be used to reduce the failure detection delay and misjudge rate as compared with the existing algorithms, and can be applied to a complex radar network environment.

Introduction to Modern EW Systems, 2nd Edition (de Martino, A.) [Book review

This book begins with an introduction of the threat systems that electronic warfare is meant to counter. An in-depth review of modern radars, communications, and electrooptical sensors includes insightful explanations of several advanced topics, including low probability of intercept (LPI) waveforms, synthetic aperture radar, and various flavors of multiple input multiple output radar. These detailed investigations lay the groundwork for the latter half of the book. The chapters on electronic warfare support methods investigate detection of LPI waveforms, specific emitter identification, and passive direction finding. The big dividends arrive in the final chapters of the book, with discussions of advanced electronic attack techniques needed to counter the advanced radars and electrooptical systems introduced earlier. The book offers detailed explanations of electronic warfare technologies and applications that are accompanied by many useful figures and plot graphs. This book, however, is not without its flaws. The gems of insight are at times adrift in a rough sea of highly inconsistent editing. The first chapter is especially egregious in this matter, with many equations containing variables whose meaning is never explained, or explained only in figures several page distant. if you are seasoned practitioner, or you are looking for advice in analyzing and designing EW systems, then I do recommend this book. The book contains a wealth of practical information, communicated via insightful figures, equations, and tables. There is plenty to learn here, even for a veteran electronic warfare engineer.

Flexible nickel aluminate (NiAl2O4) based dual-band double negative metamaterial for microwave applications

Development and analysis of materials having flexibility, low dielectric constant and tangent losses are greatly demandable in the field of wireless technology. The purpose of this paper is introducing new flexible metamaterials design based on nickel aluminate (NiAl2O4) substrate material for microwave applications. Commercially available electromagnetic simulator computer simulation technology are utilised in this investigation. The Nicolson-Ross-Weir method is used to investigate the double negative characteristics of the designed flexible metamaterial structures. At 36% concentration of nickel based flexible substrate shows measured resonances at 8.34 GHz, 12.78 GHz and 14.32 GHz. As well as for nickel 42% concentration with different design, the measured resonance shows at 11.21 GHz. The developed flexible metamaterials are suitable for modern radar and satellite application.

О ПРИМЕНЕНИИ ТЕОРИИ РАЗМЕРНОСТИ И НЕЛИНЕЙНОЙ ДИНАМИКИ В НОВОМ ВИДЕ И МЕТОДЕ РАДИОЛОКАЦИИ

Intensive evolution of the modern radar equipment and technologies put new requirements for the radio location theory as well. The work objective is not only to state our viewpoint, to define and discover a new type and a new method of radio location on the basis of fractal-and-scaling or scale-invariant principles but also, just as important, to call attention to conventional questions of the general statistical theory from the point of view of the fractal analysis, fractional calculation and the global fractal-and-scaling approach which was designed and being developed by the author during last 40 years in IREE AS of USSR (IREE RAS). The author was the first who proposed and substantiated the new type and the new method of the modern radio location namely fractal-scaling or scale-invariant radio location (Potapov, 2017, 2018). Efficiency of functionals which are determined by topology, fractional dimension, and texture of a sensed multidimensional signal was proved for synthesis of the new non-energy detectors of low-contrast objects in presence of noise. Fractal radio location is based on three postulates: - intellectual signal/image processing which is based on the fractional measure and scaling effects theory for calculating the field of fractal dimensions; - sampling of a received noisy signal relates to a class of stable non-Gaussian distributions of probabilities of fractal dimension D; - the topology maximum at the energy minimum of a received random signal. Sensitivity of a radio system has been confirmed (what is equal to an increase of the range) while using fractal and textural signature in topological detectors. It results in drastic changes in the mathematical apparatus of the theoretical radio location. The research was supported by the RAS Presidium Program «Nonlinear dynamics: fundamental problems and applications».

Phase Noise in FMCW Radar Systems

Phase noise is one of the fundamental performance parameters in modern radar, communication, spectroscopic, and metrological systems. In this paper, a phase noise theory has been developed for FMCW radar systems. A new design equation has been derived to specify the maximum bound on the allowable source phase noise level in radar systems. The nonlinear phase noise decorrelation function due to coherent mixing has been analyzed for propagation delays less than the coherence time of the reference oscillator, and the spectral broadening of target responses has been discussed for delay times greater than the coherence time. The effects of the subsystems in the transceiver chain are presented and a new model of phase noise in ADCs is discussed. Phase noise modeling techniques are presented, followed by a comparison of a PLL frequency synthesizer with a low-noise frequency synthesizer to demonstrate the reduction of phase noise sidebands for improved detection and tracking performance. Practical measurements from two millimeter wave FMCW radar systems utilizing the two frequency synthesizers have been presented to validate the developed theory.