Multifunction Radar Research Articles

Multifunctional and Tunable Radar Absorber Based on Graphene‐Integrated Active Metasurface

AbstractIn this article, a multifunctional and tunable radar absorber which can achieve dynamical modulation of absorbing frequency, bandwidth, and amplitude is presented. Such a tunable radar absorber is composed of a graphene capacitor layer and an active metasurface layer. By controlling the impedance characteristic of each layer through the external bias voltages, the absorber not only can achieve the ultrawideband electromagnetic (EM) absorbing performance, but also can be switched to a narrowband absorption mode, and its absorption amplitude can be further adjusted at each of the above operation modes. Both simulated and experimental results have demonstrated that the −10‐dB reflection bandwidth ranging from 3.55 to 19.6 GHz can be realized, and the average reflection amplitude can be dynamically tuned between −3.8 and −11.5 dB. In addition, by changing the bias voltages, the absorber can also, respectively, switch its −10 dB reflection bandwidth to 3.5−11.1 GHz and 10.9−18.9 GHz, where the larger dynamic range of amplitude modulation is obtained. The equivalent circuit model is employed to explain the tunable absorption mechanism by analyzing the impedance matching characteristics. This hybrid design approach can effectively expand the EM reconfigurable functionalities of the current tunable absorber, which may further open a novel way of the graphene application in microwave frequencies.

Sparse Imaging for Spinning Space Targets With Short Time Observation

Inverse synthetic aperture radar (ISAR) imaging is an important technique for moving target identification and classification. For the space spinning targets, a long-time observation is required to estimate the spinning parameter in the conventional ISAR imaging methods. However, for the advanced multifunctional radar, which is used for multi-target surveillance, a long-time observation for only one target is the loss outweighs the gain. To decrease the observation time, we propose a novel imaging method for spinning space targets with short time observation in this paper. Firstly, we build the imaging model by using the azimuth rotation angle caused by the spinning motion rather than the translation motion to obtain the azimuth resolution. Secondly, we utilize the orthogonal coding signals with different delays to obtain enough equivalent pulses in the short observation time. Moreover, since the equivalent pulses are block-missing to avoid overlapping of the transmitting duration and the receiving duration, we transform the imaging problem to the compressed sensing (CS) problem and solve it by modifying the Smoothed L0-norm (SL0) algorithm. Finally, both the simulations and the experiments on real data are shown to demonstrate the validity of the proposed method. Since the observing time of the proposed method only needs to cover a small percentage of one spinning period, the proposed method can be used in multi-target surveillance such as satellites and space debris.

Local territorial navigation system for regional airfields of the Arctic region RF

The specific conditions peculiar to the Northern regions create a number of difficulties in the functioning of the information airfield structure based on the traditional complex of navigation aids. These difficulties are caused by the unstable operation of satellite navigation systems in the Arctic region and territorial fragmentation. There is an urgent need to develop new approaches and technical means for the deployment of local navigation systems that ensure the operation of airfields with low traffic and difficult flight conditions. The aim of the study is to develop approaches to the creation of a new generation of multifunctional radar systems for the organization of a local navigation and information system at the airfields of the Arctic region, consisting of a ground-based multifunctional station, a portable small-sized terminal installed on board the aircraft and a board-to-ground communication line. This article proposes a promising navigation and territorial system for Arctic airfields, based on a new generation of information tools, including multifunctional radar stations. The proposed local territorial navigation and system is based on the information of the ground-based multifunctional airfield control radar. The information is transmitted to a portable small-sized terminal installed on board the aircraft. In this system, when transmitting the current situation to the on-board terminal from the multifunctional radar, which is linked to the airfield control center, it provides a safer implementation of the approach and landing modes at Arctic airfields, including in the complete absence of satellite navigation. The implementation of the proposed principles and technical solutions will enable the creation of a new generation of technical tools and the introduction of new organizational approaches to the creation of local navigation systems.

Research on Signal Processing Method of X-band Multifunctional Phased Array Radar

The signal processing algorithm is an important component of the three major technical fields of radar, and it occupies an important position in the radar system. It is the basis for phased array radar to achieve multi-function. The rapid development of modern signal processing technology has greatly promoted the development and application of radar technology. Modern radar simulation systems can simulate and optimize signal processing algorithms, and quickly adjust system parameters; because it adopts modularization and systematically encapsulated, it can be used repeatedly in different environments or platforms. The continuous development of modern signal processing technology has improved the performance of the radar system, especially in improving the radar's target detection capability and anti-jamming performance. Because signal processing occupies a very important position in radar systems, this paper studies the signal processing in radar systems. This paper analyzes the signal processing process of the multifunctional phased array radar, and conducts corresponding analysis and research on the key technologies.

Machine Learning Aided Electronic Warfare System

In this article, a machine learning aided electronic warfare (EW) system is presented and the simulation results are discussed. The developed EW system uses an automatic decision tree generator to create engagement protocol and a fuzzy logic model to quantify threat levels. A long-short term memory (LSTM) neural network was also trained to predict the next signal set of multifunction radars. The simulation results demonstrate the effectiveness of the developed EW system's ability to engage multiple multifunction radars.

The evolutionary path of the organization of the air traffic control system in Arctic

Ensuring transport connectivity of the territories of the Arctic zone is largely provided by means of regional aviation. To ensure flight safety, it is necessary to equip small airfields with radar facilities, while it is not economically effective to use the traditional range of navigation radar facilities for airfields with a low frequency of use. Therefore, it is necessary to search for and justify new scientific and technical solutions to ensure the creation of navigation tools that solve the tasks facing the dispatching services of regional airfields in the Arctic zone. This article presents an analysis of global trends in the development of air traffic control systems and options for equipping information sensors for dispatching services for airfields in the Arctic zone. The appearance of equipment complexes for information support of regional airports and small aircraft airfields based on a highly informative multifunctional three-coordinate all-round radar is proposed. The application of the obtained results and the proposed technical solutions and principles for the construction of navigation aids for regional airports and small aircraft airfields will significantly reduce the cost of production and operation of a new generation of modular high-information radars and increase the safety of navigation systems.

Integrated approach to information support of navigation in the Arctic zone of the RF based on modern radar and navigation technologies

The existing radar and radio navigation facilities sometimes do not satisfy the increased requirements for the accuracy, efficiency and reliability of information support for navigation in the organization of movement in the rough waters of the Arctic region in difficult climatic and meteorological conditions. This article offers a comprehensive approach to the information support of navigation based on technical solutions that significantly increase the capabilities of navigation tools in the rough waters of the Arctic zone. The proposed approach to the creation of fundamentally new high-precision information tools for solving a wide range of new tasks in the Arctic zone based on radar provides a higher class of accuracy and functionality compared to those currently used. The technical requirements for radar facilities are defined and the use of a new generation of highly informative multifunctional coastal radars in combination with new mobile pilotage terminals is proposed. The application of the proposed technical solutions and the principles of building navigation systems will significantly increase the safety and efficiency of navigation in waters with increased complexity of navigation organization. The proposed approaches will ensure the solution of the such tasks as: monitoring of air, surface and ground space, local navigation system for safe navigation of ships, helicopter flight, landing of helicopters on offshore drilling platforms and ground airfields, mooring of vessels to drilling platforms and terminal berths. It also support monitoring and dispatching of ship traffic in ports and the area of responsibility of terminals, including monitoring the position of ships at anchorage. Will be sufficient simplify high-precision operational assessment of the ice situation and the weather in the radar area of responsibility, protection of offshore drilling platforms and territories of onshore terminals, information support of means of protection against potential terrorist threats.

L대역 MFR용 완전디지털배열안테나의 송수신 구조 설계 및 정렬 방법

L대역 MFR용 완전디지털배열안테나의 송수신 구조 설계 및 정렬 방법

Multi-Function Radar Signal Sorting Based on Complex Network

In complex electromagnetic environments, the challenge of signal sorting task for multi-function radars (MFRs) with various work modes has arisen. The previous methods are prone to cause the so-called “increasing batch” problem, which means that the work modes of one MFR may be sorted into multiple emitters. In this letter, a MFR signal sorting method based on complex network is proposed to tackle the problem mentioned above. The novel method utilizes limited penetrable visibility graph to construct the network from interleaved radar pulse sequences, then employs label propagation algorithm and density peak clustering to detect community structures, thus fulfilling deinterleaving of pulses from several MFRs. Simulation results show that the proposed method is effective to alleviate the “increasing batch” problem, and is also robust under non-ideal conditions.

M&S기법을 통한 다기능 레이다의 4면 동시 운용을 위한 자원관리 개발

M&S기법을 통한 다기능 레이다의 4면 동시 운용을 위한 자원관리 개발

Formation of the measuring channel of multifunction phased array radar in tracking mode

In the article is considered the principle of the formation of the measuring channel for multifunction phased array radar in tracking mode using one of the short-range air defense radar system as an example. A new approach to the problem is offered, which is based on considering the change of noise levels both in the measuring channel and in the dynamic model of the target being tracked and is adaptive to its motion in space. The number of simultaneously monitored targets is calculated under the condition of application of the proposed principle of channel formation. The efficiency of the obtained solutions is confirmed. The conclusion is made about the expediency of application of this method in the existing air defense systems, the modernization of which is currently underway.

A Study on the effect of electromagnetic interference in adjacent antenna apertures of multi-function radar for Integrated MAST

A Study on the effect of electromagnetic interference in adjacent antenna apertures of multi-function radar for Integrated MAST

Multi-Functional Radar Waveform Generation Based on Optical Frequency-Time Stitching Method

A photonic-assisted multi-functional radar waveform generator for single-chirped, counter-chirped, and dual-band linear frequency-modulated (LFM) microwave waveforms generation is proposed and experimentally demonstrated based on an optical frequency-stepped waveform (FSW) generator. The optical FSW generator is realized by an optical switch and an optical frequency shifting loop (OFSL). When an electrical rectangular LFM pulse is applied to the proposed signal generator, an optical frequency-stepped LFM signal would be generated. By carefully setting the time length and the bandwidth of the rectangular LFM pulse, we can achieve an optical linearly-chirped continuous wave. Optical frequency-time stitching is thus realized. Combining the optical linear-chirped signal with one or more optical wavelengths, and meticulously adjusting the value of the optical wavelengths, single-chirped, counter-chirped or dual-band LFM signals can be produced. An experiment is carried out. Single-chirped and counter-chirped LFM signals of 8-32 GHz over a time duration of 5 μs, and dual-band LFM signals of 8-16 GHz & 15-23 GHz and 8-20 GHz & 20-32 GHz are generated. The ambiguity functions of the generated signals are investigated.

Development of Radar Environmental Signals Simulator for Simulating Sub-array Receiving Signals of Active Phased Array Multi-function Radar

In this paper, the contents of the development of RESS(Radar Environmental Signals Simulator) for the test of active phased array multi-function radar are described. The developed RESS can simulate multiple target environments, such as target/jamming/missile response/cluster signals, by using received radar operational information and simulated scenario. It can also modulate frequency, phase, gain, timing on all waveforms operated by multi-function radar and simulated two targets and one jamming in the beam. The RESS can be used to perform functional and performance verification of the active phased array multi-function radar with sub-array receiving structures. Keywords: ë‹¤ê¸°ëŠ¥ë ˆì´ë‹¤, ë ˆì´ë‹¤ 환경 ì‹ í˜¸ Keywords: Multi-function Radar, Radar Environmental Signals

Mathematical model of optimization of preventive maintenance of transmitting active phased antenna arrangements of multifunctional radars

In the article, the authors discuss the issues of determining the reliability indicators and maintenance of transmitting active phased array antennas (AFAR) of multifunctional radars. The analysis of the existing models of reliability and maintenance of AFAR radar. It is shown that the most interesting models of transmitting AFAR reliability are the reliability model with a two-level block diagram of the AFAR and the reliability model according to the criterion of permissible reduction of the maximum radar range. Among the AFAR maintenance models, the most interesting ones were identified: the AFAR optimal preventive maintenance (ON) model with a single-level structure and the AFAR maintenance model by technical condition. Using the results of the analysis, models of reliability and optimal preventive maintenance of a multi-functional radar transmitting AFAR are constructed. The analytical expressions of the reliability indicators of a two-level AFAR are presented: the average operating time to failure and the probabilities of failure-free operation of the antenna transmitting sublattice and the transmitting AFAR as a whole. Analytical expressions are constructed for the criteria for the effectiveness of optimal software (coefficient of technical use and mathematical expectation of specific operating costs) and the criteria for gaining from software optimization. The work considers an illustrative example of calculating the reliability and optimal software of a two-level AFAR, including 6400 microwave emitting channels, arranged in 100 sublattices with 64 channels each. The mean operating time to failure and the optimal periodicity of the AFAR software were determined for three versions of the reliability indicators of the emitting channels. The graphs of the probability of failure-free operation, the coefficient of technical use and the mathematical expectation of the specific operational costs of the AFAR were constructed and analyzed. The values of the optimal periodicity and the gain from optimization are obtained. It is shown that the results of optimal software should be used at the initial stage of operation of radars with AFAR — at the stage of warranty service. At further stages of operation - the stages of post-warranty service, it is recommended to use the AFAR maintenance method according to the technical condition. The models proposed by the authors can be useful to engineers and scientists developing radars with AFAR and employees of operating organizations.

Work modes recognition and boundary identification of MFR pulse sequences with a hierarchical seq2seq LSTM

Recognition of multi-function radar (MFR) work mode in an input pulse sequence is a fundamental task to interpret the functions and behaviour of an MFR. There are three major challenges that must be addressed: (i) The received radar pulses stream may contain an unknown number of multiple work mode class segments. (ii) The intra-mode and inter-mode knowledge of a modern MFR may be too flexible and complicated to be represented and learned through traditional hand-crafted features and learning models. (iii) The variable duration of each enclosed work mode makes the identification of the transition boundaries of adjacent modes difficult. To address these challenges and implement automatic recognition of MFR work mode sequences at a pulse-level, this study develops a novel processing framework based on a time series representation of MFR work mode sequence and sequence-to-sequence (seq2seq) long short-term memory network. The proposed method can not only automatically recognise multiple complexes modulated work mode classes in a pulse sequence. Still, it can also accurately identify the transition boundaries between each class by labelling the class information for each pulse. The experimental results showed the extended capabilities and improved performance of the proposed method over the state-of-the-art work mode classification methods.

Extreme Scanning Double Shaped-Reflector Antenna With Multiple Interactions for Focal Plane Array Applications

A new type of focal plane array (FPA) reflector antenna concept is proposed with a very wide field-of-view over a wide bandwidth (20–40 GHz) for ground terminals for Ka -band satellite communication and multifunction radars. The proposed concept maximizes the percentage of active array elements up to 90% within the required scanning range of ±10° along the azimuthal plane. It combines the advantages of phased arrays in terms of wide-angle scanning and of FPA systems in terms of high antenna gain. This FPA system achieves a 15 dB higher antenna gain as compared to a phased array with a size equal to the feed array of the proposed reflector system. Based on a minimum required 80% aperture efficiency at 30 GHz, the illuminated array region is increased by a factor of 200 as compared to traditional prime-focus configurations. In addition, the FPA configuration significantly reduces the required overall array size by a factor of 1.5 as compared to conventional double-parabolic reflector configurations. Moreover, the scanning capabilities have been significantly improved as compared to classical prime-focus and double-parabolic reflectors. Since a large part of the array is active, we can obtain high effective isotropic radiated power (EIRP).

피아식별 모드-5 성능개량을 위한 다기능레이더모의기 설계

피아식별 모드-5 성능개량을 위한 다기능레이더모의기 설계

Performance Enhancement of a Naval Multi-Function Radar Signal Processor

Performance Enhancement of a Naval Multi-Function Radar Signal Processor

Recognition of Multifunction Radars Via Hierarchically Mining and Exploiting Pulse Group Patterns

Recognition of multifunction radar (MFR) is an open problem in the field of electronic intelligence. Parameters of MFR pulses are generally agile and difficult to distinguish statistically. A prospective way to realize credible MFR recognition is mining and exploiting more distinguishable high-dimensional patterns buried in pulse groups, which may be designed for implementing infrequently used radar modes such as target tracking. A high-dimensional pattern is defined according to the agile range and switching law of sequential pulse repetitive intervals within a pulse group. This article establishes deep recurrent neural networks (RNN) to discriminate and coarsely cluster different pulse groups hierarchically with respect to their sequential structures. Afterwards, RNN-based classifiers are trained to extract and exploit features within different pulse group clusters. Distinct degrees of confidence are then attached to these classifiers to indicate the discriminabilities of the corresponding pulse group clusters. The pulse group clustering and classifying models are finally cascaded to form an integrated classification model, which mines distinguishable patterns from sequentially arriving pulse groups of the same radar and accumulate them to realize MFR recognition. Simulation results demonstrate the much improved performance of the proposed method over existing counterparts in different scenarios.