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The systems of short-range radiolocation and multistatic radio holography based on multielement MIMO antenna arrays (AAs) with recirculation of orthogonal signals in the spatial feedback circuits of AA transmitting element–​​target–AA receiving element–AA transmitting element are investigated. The generalized ambiguity function in spatial coordinates for an ensemble of coherent orthogonal sounding signals with allowance for the partial propagation constants of the feedback circuits is obtained. The characteristics of the range, azimuth, and elevation resolution in MIMO retrodirective systems are determined based on the analysis of two-dimensional and one-dimensional sections of the generalized ambiguity function (GAF). For the centimeter wavelength range, the GAF cross sections of the azimuth–elevation and range–elevation are compared with and without recirculation as well as at different ranges to the target. The results show the presence of super-resolution effects in MIMO systems with spatial signal recirculation and a nontrivial dependence of the resolution on the target range.

One of possible directions of increase of efficiency of informative facilities of modern and perspective multichannel anti-aircraft missile systems that have in the composition multifunction radar is examined in the article. Existent methods of management the power resource of multifunction radar does not allow in a complete measure to use possibility of the modern radiolocation stations of anti-aircraft missile systems, including in the mode of exposure of air aims. They, as a rule, envisage the use of even parameters of this mode, id est a selection of identical power resource is on realization of measuring of coordinates of aim and transmission of commands of management a few rockets. Besides the sequence of realization of these operations in time is fixed, that not always allows to decide with the proper efficiency and exactness the tasks put before radar. Thus, unchanging order of functioning of multifunction radar in the real terms of battle work results in the decline of her potential carrying capacity and it can result in admission of aims without a fire by a zenithal rocket complex (anti-aircraft missile systems), and as a result, to non-fulfillment of the put combat mission of anti-aircraft missile systems and it worse to elimination of building protection . Thus, for overcoming of contradictions it is necessary to optimize functioning of necessity to change stopped up in multifunction radar on the stage of planning offers, algorithm of battle work that is unchanging in the loop of work of the station and to use the uninvolved time intervals for realization of other indexes of the mode of discovery. Analytical expressions over are brought for the search of air aims in the set area of zone of finding out the station. Researches over of mean value and standard deviation of errors are brought on the search of air aims in the set area of zone of finding out the station. On results the conducted analysis an optimal sector is to the search of air aim in the set area of zone of exposure of the station, came to the conclusion that programed on the stage of planning to the search of aim in the sector of k degrees for аzimut and k degrees on the corner of place(all k x k of angular directions) occupies more than time and charges of power(sentinels) resources than to search of aim of headlights in the sector of q degrees on an azimuth on q degrees on the corner of place.

Weather hazards caused by the vertical air movement are considered. It is stated that the only effective mean for their detection is the weather radar. The methods used for this purpose in modern radiolocation are listed, and the difficulties encountered in their practical implementation are discussed. A new method developed by the authors to detect the zone of local vertical movement of elementary reflectors is proposed. It is based on comparing the energy spectrum width of the output signal in the phase and amplitude detection channels.

Indoor localization is becoming increasingly important but is not yet widespread because installing the necessary infrastructure is often time-consuming and labor-intensive, which drives up the price. This paper presents an automated indoor localization system that combines all the necessary components to realize low-cost Bluetooth localization with the least data acquisition and network configuration overhead. The proposed system incorporates a sophisticated visual-inertial localization algorithm for a fully automated collection of Bluetooth signal strength data. A suitable collection of measurements can be quickly and easily performed, clearly defining which part of the space is not yet well covered by measurements. The obtained measurements, which can also be collected via the crowdsourcing approach, are used within a constrained nonlinear optimization algorithm. The latter is implemented on a smartphone and allows the online determination of the beacons’ locations and the construction of path loss models, which are validated in real-time using the particle swarm localization algorithm. The proposed system represents an advanced innovation as the application user can quickly find out when there are enough data collected for the expected radiolocation accuracy. In this way, radiolocation becomes much less time-consuming and labor-intensive as the configuration time is reduced by more than half. The experiment results show that the proposed system achieves a good trade-off in terms of network setup complexity and localization accuracy. The developed system for automated data acquisition and online modeling on a smartphone has proved to be very useful, as it can significantly simplify and speed up the installation of the Bluetooth network, especially in wide-area facilities.

Introduction: Location of weather surveillance radars near settlements, in residential areas and on airport premises makes it important to ensure safe levels of electromagnetic fields when operating these radio transmitters. Electromagnetic fields maximum permissible levels for weather radars developed in the 1980s are outdated. Our objective was to analyze modern weather surveillance radars to develop proposals for improvement of radar-generated radiofrequency field monitoring. Materials and methods: We studied trends in meteorological radiolocation and technical characteristics of modern weather radars for atmospheric sensing and weather alerts, analyzed regulations for electromagnetic fields measurements and hygienic assessment, and measured radiofrequency fields produced by weather radar antennas in open areas and at workplaces of operators. Results: We established that modern types of weather radars used in upper-air sensing systems and storm warning networks differ significantly in terms of technical characteristics and operating modes from previous generations. Developed in the 1980s, current hygienic standards for human exposures to radiofrequency fields from weather radar antennas are obsolete. Conclusions: It is essential to develop an up-to-date regulatory and method document specifying estimation and instrumental monitoring of electromagnetic fields levels generated by weather radars and measuring instruments for monitoring of pulse-modulated electromagnetic radiation.

Recently, the technology has evolved towards artificial intelligence world which include IoT (Internet of Things) and IoE (Internet of Everything) as communication between machines or between devices is possible. The development of these systems today requires electronic components capable of generating higher power and frequency levels, which is why new technologies have emerged to meet these needs, GaN HEMT technology. It has attracted a lot of attention for microwave power and high temperature applications. More recently, this technology has become a great interest to the international scientific community for the realization of low noise amplifiers which are the main components of wireless communication systems. In this paper, we modeled an LNA amplifier based on HEMT GaN transistors. This amplifier is unconditionally stable in the X-band (8–12) GHz with a gain of 38 dB, a noise factor does not exceed 2.4 dB and lower input and output reflection coefficients (S11, S22). at -14 dB and − 8 dB respectively. The designed amplifier can be integrated into radar systems, space communications systems and civilian-military radiolocation systems.

The features of the functioning of coastal radar information support, monitoring and control of the movement of marine vessels in the cramped conditions of navigation are examined and analyzed. The general issues and features of the optimization of digital processing of coordinate information in the near-radar sensing of extended marine objects under the influence of passive interference caused by the presence of the underlying sea surface and hydrometeorological formation in the form of rainfall are formulated and analyzed. Simple and effective digital algorithms have been developed for determining the azimuthal range-finding coordinates of extended objects from selected single and dispersed binary signal groups belonging to an extended radar object. The coordinates of the conditional geometric center, determined in accordance with the developed method, do not contain errors associated with the presence of a jib-trace. The results obtained by estimating the amount of mixing of the object when it moves along the channel are within the range of the real-expected values ΔD ≈ 15 meters. The developed method and its practical implementation are quite simple and effective in providing information support to the skipper in the process of escorting the vessel along the channel. Results fulfilled research in future will use in solving problem of determining the coordinates of the location of extended maritime object, as well as in the solution of similar problems when designing digital radar technics.

The article deals with the possibility of using signals of the Internet coverage, cell-phone networks, radio and television signals to provide detection of air targets. The advantages, disadvantages, composition and principle of operation of a semi-active radar system are considered in this article. Issues of technical realization of antennas and receivers of a semi-active radar system are investigated. An algorithm for signal processing in a semi-active radar system is proposed. For fulfilling the tasks of air surveillance and timely alerting of the air defense system to a higher degree of readiness when detecting the air threats and airborne intelligence assets of the enemy, currently in the area of the Operation of the Joint Forces the radar air surveillance system is deployed. This system is made up of traditional active radiolocation tools. The main disadvantage of such a system is its low survivability, which is due to the radiated signals, and, consequently, the ease of reconnaissance of radar positions by the enemy. Preservation of radar air surveillance system positions undetected and, consequently, the survivability of those radar systems is possible by supplementing them with the means of semi-active radar. Also, in the context of the so-called hybrid war in the area of Operation of the Joint Forces a ramified system of radio equipment continues to operate that can provide illumination field.

The Ultra-High Frequency (UHF) band occupies a very vital region in the spectrum and is becoming very congested because many applications use it. The capsule camera (CapCam), an ultra-low power wireless device, is a Short Range Device (SRD) application that utilizes the UHF spectrum for medical endoscopy and it is designed to operate at the 430-440MHz frequency band range. This study will focus on the interference between the CapCam and other systems operating in the frequency of 435MHz and adjacent bands. Other systems that can operate in this band include non-specific SRD and radiolocation services such as airborne radar and ground radar stations. The Minimum Coupling Loss (MCL) method is implemented in this study. The findings showed that restricted distances between the CapCam and other services must be considered when the CapCam is in use. This should be done to avoid harmful interference from the CapCam especially in the case of radiolocation services.

Small-scale irregularities of the ionosphere have a significant impact on the operation of various technological systems. In this paper, two independent methods are used to study them: radio illumination with satellite signals (the receiver is located at the Lomonosov Moscow State University) and radar (the DPS-4 ionosonde is located at IZMIRAN). To interpret the experimental data, a special program LocalDrift was developed to calculate the direction and speed of drift in a local area with small-scale irregularities. The data were obtained in the mid-latitude zone during September - December 2011 in quiet geomagnetic conditions. Comparison of the direction of the medium-scale irregularities drift and the orientation of the transverse anisotropy of small-scale irregularities in the F-region showed good agreement between these experimental data. The difference from the results of using the standard DriftExplorer program is shown.

The article reviews selected issues associated with the preparation, organization and execution of field training targeting the practical functional verification of passive sensors installed on-board various land, sea and air platforms. The APART-GAS trials combined the training of two NATO research task groups (RTG) operating within the SET Panel: SET-242 on passive radiolocation on mobile platforms (Passive Coherent Locators on Mobile Platforms) and SET-258 on multiband active and passive radars used in various military scenarios (DMPAR - Deployable Multiband Passive Active Radar Deployment and Assessment in Military Scenarios). The specificity of passive sensors, as well as the wide range of their applications resulted in numerous complications at the stage of developing and executing test scenarios conducted with the use of different aircraft types, including vertical launch rockets, water vessels and land vehicles. The article discusses successively the activities supporting the Warsaw University of Technology implemented by the Air Force Institute of Technology (AFIT). in the field of installing the sensors on individual platform, aircraft flight planning and their coordination in the course of the trials. AFIT performed the issues regarding the recording and imaging radiolocation data from the sensors participating in the trials and coupled within an Unclassified Radar Network (URN).

In the paper, a new approach to the estimation of the localization of flying objects on the basis of multiple radiolocation sources has been proposed. The basic purpose of the radiolocation is the detection and tracking of objects. The main task of a tracking system is the estimation and prediction of localization and motion of tracked objects. In the classical tracking systems, the estimation of localization and motion of tracked objects is based on the series of measurements performed by a single radar. Measurements obtained from other sources are not taken directly into account. It is possible to assess the estimate of a tracking object on the basis of the different sources of information, applying, for example, least squares method (LSM). However, such solution is seldom applied in practice, because necessary formulas are rather complicated. In this paper, a new approach is proposed. The key idea of the proposed approach is so called matrix of precision. This approach makes possible tracking not only on the basis of radar signals, but also on the basis of bearings. It makes also possible the tracking of objects on the basis of multiple information sources. Simplicity is the main attribute of proposed estimators. Their iterative form corresponds well with the prediction-correction tracking model, commonly applied in radiolocation. In the paper numerical examples presenting advantages of the proposed approach are shown. The paper consists of seven parts. Introduction is the first one. In the second part the idea of the matrix of precision is presented and it is demonstrated how it can be used to uniformly describe the dispersion of measurement. Traditionally, the measurement dispersion is described by a matrix of covariance. Formally, the matrix of precision is an inverse of the matrix of covariance. However, these two ways of description are not interchangeable. If an error distribution is described by the singular matrix of precision then the corresponding matrix of covariance does not exist, more precisely, it contains infinite values. It means in practice that some components of a measured vector are not measurable, in other words, an error of measurement can be arbitrarily large. The application of the matrix of precision makes possible an uniform description of measurements taken from various sources of information, even if measurements come from different devices and measure different components. Zero precision corresponds to components which are not measured. In the third part, the problem of estimation of stationary parameters is formulated. Using the matrix of precision, the simple solution of the problem is presented. It appears that the

The solution of the tasks assigned to the National Guard of the state implies the presence of certain forces and means with the appropriate technical equipment. A well-known place among such tasks is security of important state facilities. Various physical effects and methods, including radar, are used to create security systems. The development of radar technology and technology made it possible to increase both the quantity and quality of the received information, as well as the use of radar stations for observing living objects. The industry today produces bioradioradars for detecting people and controlling their movements. All samples are made in a single-position version and have a relatively high cost, the fact of their work is easily detected, which facilitates their suppression, including force. In order to increase the secrecy of work, it is proposed to use the methods of separated, more precisely, bistatic location to control the area in front of particularly important objects. The defining detection index is the effective reflective surface (ERS), which is about 1m2for a person. Equipment, weapons and protective equipment contributes to the increase in the ERS. Given the small reflective surface of biological objects, it is proposed to limit the area of responsibility to the sector form in which, at a certain bistatic angle, the effect of a significant increase in the signal/(interference+noise) ratio is manifested. For a specific definition of the gain, it is necessary to choose the operating frequency of the bistatic system and its geometry. For greater secrecy, it is advisable to use the transmitters of radio and television broadcasting, mobile communications, etc. The estimates found, for example, when using digital television transmitters (T2), indicate that the creation of a secretive bistatic system is quite possible – at least in a geometric interpretation.

The task of achieving the resolution in the bandwidth radar with the increased range synthesis aperture for the purpose of recognizing the targets is relevant at the present time, despite significant achievements in this topic. From the point of view of the recognition of objects to a certain type or class of distinction 0.2-0.3 meters is sufficient to solve this problem. However, the problem of obtaining ultra-distinction in a bandwidth radar station with the increased range synthesis aperture requires solving a number of issues, in particular the evaluation of filter parameters for the formation of a flat wave front in a radars with synthetic aperture. One of the solutions of this problem is the inclusion of additional algorithms for the reflected signal processing, which artificially forms a quasi-flat front of the sounding signal wave. In the current article, the question of the selection and evaluation of filter parameters for the formation of a flat wave front in a radar station with ultra-high resolution is being solved. In order to achieve this goal, the article proposes: - a step-by-step procedure for digital filters calculating; - estimation of the number of samples of digital filters with impulse characteristics of finite length in the channels and the observation band; - estimation of the number of samples of impulse characteristics of filters. For the formation of a quasi-flat wave front in a radar station with the increased range synthesis aperture it is necessary to use digital filters with impulse characteristics of finite length and linear phase characteristics in processing algorithms. From the point of view of obtaining minimal losses in the resolution of radar stations with a synthesized aperture along the traveling distance in the process of artificial formation of the flat front of the sounding signal wave, it is expedient to use Chebyshev approximation of the amplitude-frequency characteristic of optimal filters with a minimax error. The width of the transition band of such filters is much smaller than that of other optimal filters with the same values of the countdowns., Задача достижения разрешающей способности в полосовой РЛС с синтезированием апертуры повышенной дальности для распознавания целей является актуальной в настоящее время, несмотря на значительные достижения в этом вопросе. С точки зрения распознавания объектов определенного типа, вида или класса разрешение 0.2-0.3 метра достаточно для решения этой задачи. Однако проблема получения сверхвысокого разрешения в полосовой РЛС с синтезированием апертуры повышенной дальности действия требует решения ряда вопросов, в частности оценки параметров фильтров для формирования плоского фронта волны в радиолокационных станциях с синтезированной апертурой. Для формирования квазиплоского фронта волны в полосовой РЛС с синтезированием апертуры повышенной дальности в алгоритмах обработки необходимо использовать цифровые фильтры с импульсными характеристиками конеч\-ной длины и линейной фазовой характеристикой. С точки зрения получения минимальных потерь в разрешающей способности РСА по путевой дальности в процессе искусственного формирования плоского фронта волны зондирующего сигнала целесообразно использовать чебышевскую аппроксимацию АЧХ оптимальных фильтров с минимаксной ошибкой. Ширина переходной полосы таких фильтров значительно меньше, чем в других оптимальных фильтрах с такими же значениями количества отсчетов импульсных характеристик, амплитудами пульсаций в полосе пропускания и режекции., Задача досягнення розрізнювальної здатності в смуговій радіолокаційній станції із синтезуванням апертури підвищеної дальності дії для розпізнавання цілей є актуальною на теперішній час, незважаючи на значні досягнення в цьому питанні. З точки зору розпізнавання об’єктів до певного типу, виду або класу розрізнення 0.2-0.3 метра є достатнім для вирішення цієї задачі. Проте проблема отримання надвисокого розрізнення в смуговій радіолокаційній станції із синтезуванням апертури підвищеної дальності дії вимагає вирішення ряду питань, зокрема оцінки параметрів фільтрів для формування плоского фронту хвилі в радіолокаційних станція із синтезованою апертурою. Одним з шляхів вирішення цієї проблеми є введення додаткових алгоритмів обробки відбитого сигналу, які штучно формують квазіплоский фронт хвилі зондувального сигналу. В даній статті вирішується питання вибору та оцінки параметрів фільтрів для формування плоского фронту хвилі в радіолокаційній станції надвисокого розрізнення підвищеної дальності дії. Для досягнення зазначеної мети в статті запропоновано: поетапний порядок розрахунку цифрових фільтрів; оцінка кількості відліків цифрових фільтрів з імпульсними характеристиками кінцевої довжини в каналах і смузі спостереження; оцінка кількості відліків імпульсної характеристики фільтрів. Для формування квазіплоского фронту хвилі в смуговій радіолокаційній станції із синтезуванням апертури надвисокого розрізнення підвищеної дальності дій в алгоритмах обробки необхідно використати цифрові фільтри з імпульсними характеристиками кінцевої довжини і лінійною фазовою характеристикою. З точки зору отримання мінімальних втрат в розрізнювальній здатності радіолокаційних станцій із синтезованою апертурою по шляховій дальності в процесі штучного формування плоского фронту хвилі зондувального сигналу доцільно використати чебишевську апроксимацію амплітудно-частотної характеристики оптимальних фільтрів з мінімаксною помилкою. Ширина перехідної смуги таких фільтрів значно менша, ніж у інших оптимальних фільтрів з такими ж значеннями кількості відліків імпульсних характеристик, амплітудами пульсацій в смузі пропускання і режекції.

One of the most popular microwave bands now is the W-band. It is attractive by the atmospheric transparency window, which makes it promising for a number of scientific and technical applications including radiolocation, communication, detection of hidden objects and the creation of medical devices. The output power level in both continuous and pulsed regimes for the aforementioned applications should be in the order of several kilowatts and above. This makes the gyrotron one of the most high-potential sources of electromagnetic radiation in this range.The alternate design of an electrodynamic system based on the use of a diaphragm in a wave transition is proposed. This system has been theoretically and numerically analyzed for a W-band gyrotron at the third harmonic of the cyclotron frequency. The optimal parameters of the diaphragm and its position have been selected. With that parameters, the highest value of the starting current of the competing mode is reached while maintaining the starting current of the operating mode. It allows to increase the output radiation power by more than 7 times. An estimate of the accuracy of the manufacturing of the diaphragm has been made. It holds out a hope of scaling this selection method into higher frequency ranges. Further development of this system is primarily tied with a more complex optimization of the system particularly the variation of the length of the cylindrical part of the cavity, which will allow reducing the share of ohmic losses while maintaining high efficiency.The paper is based on the research results, which was conducted in the framework of projects of the Russian Science Foundation No. 17-79-10422. Keywords: Gyrotron, W-band, Mode selection

This paper presents the results of investigations on the beamforming of a low-frequency radio-telescope LOFAR which can be used as a receiver in passive coherent location (PCL) radars for aerial and space object detection and tracking. The use of a LOFAR radio-telescope for the passive tracking of space objects can be a highly cost-effective solution due to the fact that most of the necessary equipment needed for passive radiolocation already exists in the form of LOFAR stations. The capability of the radiolocation of planes by a single LOFAR station in Borowiec is considered to be ‘proof of concept’ for future research focused on the localization of space objects. Beam patterns of single sets of LOFAR antennas (known as tiles), as well as for the entire LOFAR station, are presented and thoroughly discussed in the paper. Issues related to grating lobes in LOFAR beam patterns are also highlighted. A beamforming algorithm used for passive radiolocation purposes, exploiting data collected by a LOFAR station, is also discussed. The results of preliminary experiments carried out with real signals collected by the LOFAR station in Borowiec, Poland confirm that the appropriate beamforming can significantly increase the radar’s detection range, as well as the detection’s certainty.

There is a need for analog-to-digital converters with high signal-to-noise ratio and large signal bandwidth to solve a number of radiolocation problems. Developing such ADC is a challenge in analog core, digital core and verification. The design flow of the digital core must take into account possibility of changing the analog core specification at any design stage, provide ability to quickly obtain synthesizable RTL code of the device and conduct its functional verification. Automation tools were used to reduce the time spent on development and verification. This article describes the developed software package that generates synthesizable RTL code and verification environment configurations for each stage of development of the analog core of the multi-stage sigma-delta ADC. Results after functional verification are presented.

The chapter is dedicated to the complex of the interrelated issues of design development, fabrication and application of the various antennas and antenna devices for the systems of radiolocation and communications. Here are listed the basic parameters and types of the produced in the world and in Russia systems, examples are cited of the most effective design solutions (including antennas for the potable wireless systems of the standard WIMAX/WLAN), wide band micro strip antennas – with the enhanced gain ratio, wide band microwave antennas of the running wave, clipped directly to garments and even borne on the human body, multiband PAT – antennas, micro strip antennas on the thin substrate, flat reflecting printed antennas for the cellular communications systems, triple range antennas for the systems of uninterrupted communications, original wide band antennas on the ceramic substrate, wide band multi-spiral antennas with polarization and etc., with the detail consideration of the computing methods of these antennas by means of the contemporary means of the automated design development.

The chapter is dedicated to the specific problems and peculiarities of arrangement of the process of designing the radiolocation integrated circuits.

This introductory chapter is dedicated to concise presentation of the theoretical basics of radiolocation. Here in synopsis are represented the theoretical basics of functioning of the radiolocation devices, starting with the chronology of the historical events, related to creation of the first radiolocation stations, description of the basic functional principles of radars, typical algorithms of signal processing (from measurement of the distance to the target, determination of the angle of the target elevation and of the radar definition as per the target), characteristics of aerials (signal amplification, aperture of the aerial, radar’ cross-section, noises and echo-signals), as well as the general information about the radiolocation stations: classification, frequency ranges of work, performance parameters, comparison of the activity zones of the passive range-difference detection systems of the various radio irradiation sources, differences between the military and civil radars.

The chapter is dedicated to investigation of the peculiarities of construction of the systems for the radiolocation signals digital processing (SDP) on the basis of the microelectronic element base – special purpose microprocessor complexes of the very large scale integrated circuits (VLSIs).

The paper presents the results of studies on analysis, implementation and testing of beamforming methods which can be used for enhancement of radiolocation capabilities of radioastronomical LOFAR station in the context of its use for passive radiolocation. Using the LOFAR system for passive radiolocation might be an highly cost-effective solution for location of objects due to the fact that most of the necessary equipment already exists. In this paper the location of planes by a single LOFAR station in Borowiec was considered as the proof of concept for a more complex system for localizing space objects in the future. The beamforming Phase-Shift algorithm used for passive radiolocation by means of LOFAR station was presented and thoroughly discussed. Beam patterns of steered antenna array of a LOFAR station and its single subapertures, known as tiles, were shown. Occurrence of grating lobes in presented beam patterns is also discussed. The results of preliminary experiments performed with real signals registered by the LOFAR station in Borowiec confirm the efficiency regarding enhancement of radiolocation capabilities, increasing radar’s range and certainty of detection by means of beamforming.

In the report questions of assessment of efficiency of recognition of radio-emitting objects with use of set of signal signs both the systems of radiolocation, and communication systems and controls are considered. Results of experimental studies on the basis of these objects taking into account parameters of onboard radars and communication systems are provided.

This paper provides an overview of the characteristics of selected types of active interference dedicated to medium range surveillance radars. That is why at the very beginning examples of platforms used to interfere the operations of both land based surveillance radars and radars mounted on boards of combat aircraft are characterized. The paper focuses mostly on surveillance radars and their resistance to noise jamming. An example calculation of effective jamming range in relation to a medium range radar is considered in the text. Moreover a graphic representation of the influence of jamming on the operation of a radar with reference to the application of jamming and thereof lack are discussed. The basic aim of the considerations is an efficiency assessment of the jamming impact on the operation of the radar. Among others the effectiveness of the radar transmit pulse power changing is assessed with regard to the prevention of intentional jamming. The conclusions provide exemplary methods of mitigating the impact of jamming on the operation of the radar. Additionally the paper provides information on priorities to be taken into consideration in the field of contemporary radiolocation.

The article describes the practical application of artificial neural network in the processing of post-processing radar information, such as echoes filtration from the solid objects, automatic establishment of recognition zones, work with disturbances, tracking of aircraft and testing their flight characteristics, and even an attempt to identify the type of aircraft based on the obtained characteristic of the effective reflection surface of the object. The measurement results have been presented in the form of appropriate tables, charts, screenshots conclusions and implementation possibilities in the current generation of radiolocation devices.

Radio frequency fields have many applications in modern communications. The most common sources of such field are mobile communications, wireless local area networks and broadcasting towers. The introduction of new unmanned aerial vehicles and adaptive navigation systems in all types of transport necessitates a sharp increase in the number of radar installations of different frequency and intensity used. The present work is aimed at studying electromagnetic fields in buildings in the vicinity of a radar installation (marine radiolocation installation type Don with a slotted waveguide antenna, with operating frequency 9 GHz and output power 41kW). The parameters of the electromagnetic field were measured in the building below the radar installation and the risk for the workers in the building was assessed.

The International Telecommunication Union (ITU) Resolution 612, in combination with Report ITU-R M2.234 (11/2011) and Recommendation ITU-R M.1874-1 (02/2013), regulates the use of the radiolocation services between 3 and 50 MHz to support high frequency oceanographic radar (HFR) operations. The operational frame for HFR systems include: band sharing capabilities, such as synchronization of the signal modulation, pulse shaping and multiple levels of filtering, to reduce out-of-band interferences, low radiated power, directional transmission antenna, to reduce emission over land. Resolution 612 also aims at reducing the use of spectral bands, either through the application of existing band-sharing capabilities, the reduction of the spectral leakage to neighboring frequency bands, or the development and implementation of listen-before-talk (LBT) capabilities. While the LBT mode is operational and commonly used at several phased-array HFR installations, the implementation to commercial direction-finding systems does not appear to be available yet. In this paper, a proof-of-concept is provided for the implementation of the LBT mode for commercial SeaSonde HFRs deployed in Australia, with potential for applications in other networks and installations elsewhere. Potential critical aspects for systems operated under this configuration are also pointed out. Both the receiver and the transmitter antennas may lose efficiency if the frequency offset from the resonant frequency or calibration pattern are too large. Radial resolution clearly degrades when a dynamical adaptation of the bandwidth is performed, which results in non-homogeneous spatial resolution and reduction of the quality of the data. A recommendation would be to perform the LBT-adapt scans after a full measurement cycle (1-h or 3-h, depending on the system configuration) is concluded. Mutual cross-interference from clock offsets between two HFR systems may bias the frequency scans when the site computers controlling data acquisitions are not properly time-synchronized.

The research of the basic parametric characteristics of integrated circuits that affect the radar equipment was conducted, a comparative analysis of modulators and demodulators was carried out and the methodological approach of assessment of effectiveness of interchangeability of chips in a radar equipment is tested.

A frequency reconfigurable diagonally trimmed square patch antenna for satellite communications and radiolocation applications is proposed in this paper. The proposed antenna resonates between two frequencies (3.21 and 3.40 GHz) by switching ON and OFF PIN diode. This antenna design provides elliptical polarization in both the diode-switching states. This is achieved using a simple slotted structure of the microstrip antenna, which consists of a single-layer, single-feed diagonally trimmed patch. Experimental results show that the proposed antenna provides the highest gain of 2.58 dBi when the diode is OFF and a maximum bandwidth of 210 MHz when the diode is ON for Voltage Standing Wave Ratio (VSWR)

This article describes radiolocation devices dedicated to the detection and tracking of small high-speed ballistic objects and multifunctional radars. This functionality is implemented by applying space search technology and adaptive algorithms for detection and tracking of air objects in parallel with classic search and tracking of objects in controlled airspace. This article presents examples of the construction of both types of devices produced by foreign companies and Polish industry. The following sections present methods for testing radars with the function of tracking small high-speed ballistic objects along with examples of results of observations of combat ammunition.

It is proposed to use the tomographic approach to the problem of detecting and imaging concealed utility networks. This approach is based on generating the three-dimensional radio images of the space being explored from the results of measuring its location wave projections in a dual-polarization measurement mode. The problem is solved by focusing radiation first on the “air–dielectric” interface and then inside the dielectric. Experimental data processing results and reconstructed threedimensional radio tomograms are provided for a “twisted pair” cable and a fiber-optic cable with no metallic inclusions. The results confirm the operability of the approach.

This paper presents design of an hp-shaped reconfigurable antenna printed on a 1.6 mm thicker FR-4 substrate. The antenna works in four distinct modes frequency modes, contingent on the status of the two switches. Six resonant bands are obtained by the antenna, i.e. 1.8 GHz (GSM1800), 2.10 (3G LTE-advanced), 3.15 GHz (Radiolocation), 3.50 GHz (WiMAX), 3.88 GHz (Fixed satellite services) and 5.56 GHz (WLAN). The antenna gives optimum performance in terms of gain (1.84–3.22 dB), bandwidth (180–1020 MHz) and radiation efficiency (91–95%) in these six frequency bands. The antenna is properly matched in all these bands (VSWR

The potential of Doppler weather radars in estimating the speed and direction of airflows within the area of coverage is investigated. It is demonstrated that the usage of one radar does notre-trieve the field of these parame ters but makes possible the solution of partial problems. Different ways of solution are considered. The method based on multiposition radiolocation is proposed as the most promising one.

In this article, a novel metasurface absorber is designed for RCS reduction as well as high isolation in a 4-elements MIMO antenna. A unit cell of metasurface absorber is amalgamated by concentric circular and elliptical-shaped rings with four 300 ohms lumped resistances. Absorbance at the intended frequency band (i.e. 8.75 GHz-9.00 GHz) of metasurface absorber is more than 90.0% and its reflectivity is tending to zero. Therefore, the isolation between antennas due to this absorbance is improved by 12 dB, and the total isolation of the antenna is achieved less than 23 dB. Similarly, the Radar cross-section (RCS) of the antenna is also significantly reduced by 10dBm2. This MIMO antenna with an absorbing structure is fabricated on a richly existing FR4 substrate with dimensions of 55 × 40 × 1 mm3. The performance of the designed MIMO antenna is also judged by diversity parameters similar to Envelope correlation coefficient (ECC), Directive gain (DG), Mean effective gain (MEG), Channel capacity loss (CCL), Total Active Reflection Coefficient (TARC), and channel capacity, etc. for the proposed frequency band. The simulated and measured ECC of the proposed MIMO is less than 0.073 which exhibits that this antenna is suitable for military application in radiolocation and navigation.

In this paper we consider the radiolocation equation for the Incoherent Scatter Radar (ISR) method, the equation accounts for refraction effect and Faraday rotation in the VHF frequency domain. Our research shows that we cannot ignore refraction in processing the incoherent scatter data when lag-product is used to obtain the ionospheric characteristics. Effect of refraction can explain some uncertainties that arise during processing and interpretation of the ISR data. This effect shows that together with the "ion line" of incoherent scatter spectrum, a relatively small "electron line" also plays a significant role in forming the ionosphere response. The “electron line” behaves as an additional "radar induced" wideband radiolocation signal affected by refraction and Faraday rotation; it depends on the ionosphere temperature and ion composition. The presence of a wideband “electron line” produces specific distortions of the ISR spectrum during 3D-forming of the ionosphere response inside the ISR antenna diagram pattern. During testing, we found that the signal from the ISR “electron line” can be measured at much higher altitudes comparing to the “ion line”. Hence, to improve the incoherent scatter technique, we can take the “electron line” and refraction into account.

The publication described selected issues from the research area of modern radar equipment produced by the Polish industrial plants, using military aircrafts of various types. A technical development caused a substantial improvement of detection parameters of flying objects by radar sensors what forces changes in research methods used to verify tactical and technical parameters of these devices. The article covers research methods of radar equipment, pilots’ assistive devices as well as methods of logging and processing the measurement data applied in the Research Laboratory for Radar Equipment and Aeronautical Engineering of the AFIT (pol. Laboratorium Badań Urządzeń Radarowych i Techniki Lotniczej ITWL).

The method of study of magnetically oriented ionosphere inhomogeneities based on the analysis of radar decametric emission backscattering on inhomogeneities is proposed. It is shown that certain conditions, including the orientation of the propagation route relative to the Earth’s magnetic field lines and the polarization and frequency of the emitted wave, make possible resonant backscattering of radiolocation system emission on magnetically oriented ionosphere inhomogeneities. The paper presents the results of experimental observation of scattering in Kamchatka Peninsula. They demonstrated the opportunity to evaluate the extension of the scattering region, the vertical and horizontal components of the velocities of magnetically oriented inhomogeneities, and the frequency dependence of these parameters.

Results of laboratory measurements of the dielectric characteristics of lunar soil samples returned to the Earth by the Luna and Apollo missions have been analyzed. The feasibility of determining the density of the upper cover of the Moon from the permittivity, which is restored as a result of solving the inverse problem of radiolocation, has been discussed. A formula has been proposed for approximating the frequency dependence of the loss tangent for the regolith and bedrock. Relationships have been deduced for estimating the percentage of metal oxides in the lunar soil.

International audience; The Galileo E6 band operates at a nonprimary frequency band within the L‐band. This presents challenging situations in the vicinity of other, legitimate, radiolocation services. This is the case for Air Traffic Control (ATC) radar, which is seen as an in‐band–pulsed interference by a GNSS receiver. This paper provides a detailed study of the impact of such interference, as well as localization approaches. Particularly, the paper describes the ATC jamming event captured on a GNSS permanent station, its effects on a real receiver, and how it was tracked to localize the source of interference. An ultra low‐cost array‐based solution is prototyped, based on commercial off‐the‐shelf devices, that implements a two‐element array. Experimental results are shown and discussed using real data, validating the localization performance of the prototype.

One of the focus areas for radar monitoring tasks is to obtain non-coordinate target information. Such focus area implies tasks of target discrimination and evaluation of its geometric characteristics. Both tasks involve availability of information on scattering properties of radar targets due to their types. In particular, the solution of these tasks is based on the use of information on statistical characteristics of radar signal reflected from targets. Besides, it is necessary to be aware of the functional connection between parameters of scattered RF emission of radar targets and their physical, chemical, and electrical parameters. This task was solved in Chap. 1.

The paper examines the process of aerial vehicle coordinates detection using the multilateration radio system. Spatial diversity of multilateration system under investigation is achieved by single transmitting node and array of anchor nodes. The original results and findings are as follows: detection at the receiver node position of azimuth angles between aerial vehicle and signal irradiated by transmitter. The following procedure is used to determine co-operative range measurement, radial velocity and relative cartesian coordinates of object of interest and vector velocities of aerial vehicle.

Radiolocation within indoor environments is a challenge due to the dynamic variations caused by movement of objects and the complex multipath radio propagation. Therefore techniques that are suitable for indoor scenarios need to be robust to the multipath effects, which leads to additional power consumption and complexity. For instance, Ultra-wideband transmission can overcome multipath impact at the expense of requiring at least three access points in range with high bandwidth transmission. Such approaches are not feasible in commodity and low power IoT device tracking using legacy transmitter devices, such as WiFi or Bluetooth. Therefore, the proposed approach to address this problem is to selectively use Angle of Arrival (AoA) capabilities in access points, with the need for only two, to adaptively take measurements as compatible devices move around the environment in order to update radio maps used for optimising this process. In doing so important inferences about the dynamic environment can be exploited to adapt the measurement intervals to reduce the measurements and processing required and conserve power.

In military radars a special attention is paid to fast moving targets and the ballistic objects. Detection, identification and tracking of such objects is a critical task in air surveillance radars, artillery radars and C-RAM systems. The development of algorithms that realize this aim requires testing many potential radiolocation situations. Preliminary tests can be realized using a software simulator of air picture generated by a radar. This article presents a simulator that is capable of generating the plots accordingly to the simulated radar’s operating mode and its operational parameters. The objects modeled in the simulator are among the others the ones with the ballistic trajectory. Except the objects’ plots there are generated the plots that result from false alarms. Every simulated plot contains the information about position (range, azimuth and elevation) and the value of the echo signal amplitude at the output of the detector. The principles of operation of the particular parts of simulator and selected results are presented.

This work presents the design of a multi-band wearable monopole patch antenna integrated with a defected ground structure. The designed antenna operates over four distinct frequencies viz., 2.12 GHz, 4.78 GHz, 5.57 GHz and 6.11 GHz with the respective fractional bandwidths of 0.94%, 1.04%, 2.5% and 8.18%. The maximum return loss of 51 dB has been achieved over the band 6.05-6.55 GHz while the maximum realized gain of 10.70 dB has been obtained at 6.15 GHz. The simulation has been carried out using Ansys HFSS which has been validated using CST Microwave Studio. The antenna exhibits endfire radiation pattern in its far-field characteristics. The proposed antenna finds its applications in maritime radar, radio LAN, radiolocation, passive sensor and weather radar applications, satellite communication etc.

A planar modified Sierpinski---Meander hybrid fractal antenna suitable for future wireless communication networks capable of exhibiting heptaband behavior has been presented in this paper. Proposed radiating structure is obtained by combining a modified Sierpinski gasket and Meander like antenna (for lower frequency) to obtain a hybrid structure exhibiting multiband behavior. Difficulty of designing a complex fractal structure has been eased by using scripting method (*.vbs) in HFSS obtained from IFS and MATLAB. Proposed antenna has partial-defected L-shaped ground structure which helps to obtain higher values of Gain. It has dimensions of 54 × 46 × 1.6 mm3 and resonates at 2.4, 4.437, 5.38, 7.01, 7.60, 8.41 and 9.09 GHz which covers useful applications like Bluetooth, WLAN, Wi-Fi, ISM, RFID, 4G/LTE, radiolocation and mobile/fixed satellite service. Prototype of the proposed structure is fabricated on FR4 substrate and tested. Measured results are analyzed and compared which are in good agreement with the simulated ones.

Estimation algorithms of coordinates of the Earth surface elements in 3D radio-wave imaging system based on the airborne Doppler radar during the low-altitude flight were proposed. In addition, the applicability of the algorithms was demonstrated by using the computer simulation method.

In the work we provide a theoretical verification for various techniques of increasing direction finding accuracy of on-board radio systems equipped with “antenna – radome” systems, based on representing a direction finding characteristic of an “antenna – radome” system as a power series. Moreover, we describe design principles and flowcharts of direction finders ensuring a multiple increase in detection accuracy. Consequently, we analyse direction finding errors, and supply our research with the results of investigating a device implementing the techniques suggested.

The modern world is characterized by the pervasive use of computers, sensors, robotics, and Internet connectivity. This represents a new industrial revolution, dubbed Industry 4.0. In this paper, we discuss the application of the Industry 4.0 paradigm to creating a robotic search-and-detection platform intended for humanitarian demining. This is based on the combination and interaction of two microwave radars - including a UWB multi-sensor array, and a holographic imager - as well as 3-D optical cameras, remote navigation, and GPS tracking. The concepts introduced by Industry 4.0 represent an important opportunity for the scientific community to adopt new approaches in the design and use of UWB radar systems, and how data from these systems can be shared, archived, and processed in a decentralized manner accessible to the worldwide community

To solve problems of high-precision mapping of spatially extended objects regardless of weather conditions and time of day, radar imaging systems are used. The globality and efficiency of the survey is provided by the placement of radars on aerospace carriers. At the same time, there has been a proliferation of side-scan radars (providing a wide viewing range with a low spatial resolution) and antenna aperture synthesis radars (these provide high resolution in spatial coordinates, which depends on the type of survey). Radars used for imaging are classified according to various characteristics determining their advantages and disadvantages. Among such features, we can also distinguish the radar viewing area, which is currently limited to angles of 15° to 60° to the right and left of the observation in the nadir. The viewing range from -15° to + 15° from the nadir is characterized by a low resolution in range and traditionally is not visible by these radars (the socalled “blind zone”). In this regard, an alternative system for building radar images from aerospace carriers is proposed. It will provide imaging with high angular resolution of the viewing range from -15° to + 15° from the nadir. The main feature of the developed radar lies in the signal processing algorithm that combines methods of active (the presence of probing UWB signal) and passive (aperture synthesis) radiolocation. In addition, the radar implements a new method of “spectral aperture synthesis,” which allows the transition from processing of UWB signals with the continuum spectrum to processing multi-band signal processing.

The new kind and approach of up-to-date radiolocation, fractal-scaling or scale-invariant radiolocation has been proposed. The fractal-and-scaling approach to the MIMO radar and UAS has been developed. The main ideas and strategic directions in synthesis of fundamentally new topological radar detectors of low-contrast objects have been considered. New ideas called cognitive radar in fractal-scaling design have been discussed. The new topologic signs and methods of detection of low-contrast objects against the background of high-intensity noise are presented. The main purpose of this work is to interpret the main directions of radio physics, radio engineering and radiolocation in “fractal” language that makes new ways and generalizations on future promising radio systems.