Study of Fire Control Radar Technology Countering Electronic Attack

The radar system designer is constrained by limited budgets for resources such as cost, weight, prime power, and volume. Under these constraints, the designer attempts to maximize the radar system performance. After selecting the operating frequency band and the basic design approach, the primary way to improve radar performance is to increase the average radiated power (P) and the antenna aperture area (A). Search radar performance scales with the power-aperture product PA, track radar performance scales in proportion to PA/sup 2/, and fire control radar performance scales as PA/sup 3/ of PA/sup 4/. After allocating resources to all other sub-systems (e.g. computers and signal processors), the system designer must determine how to balance resource allocation between P and A. This analysis determines the optimal allocation of the critical resource that is exhausted before others. If the resource cost of P and A are linear and independent, the analysis shows that for a search radar the critical resource should be divided equally between P and A. For a track radar, one-third of the critical resource should be allocated to P and two-thirds to A. For a fire control radar, one-fourth or one-fifth of the critical resource should be allocated to P, with the remainder allocated to A. The analysis also provides results to optimally balance P and A in the case where the resource costs are non-linear functions. The appendix reviews the relationship between P, A, and radar performance.

Most of the airborne fire control radars (FCR) are migrating to the modern active electronically steered array (AESA) technology from mechanically scanned array (MSA) technology. The FCR radars are normally installed in the nose of the aircraft that acts as a radome. Apart from structural characteristics, the Electromagnetic characteristics of the radome are essential for the performance of the radar. It leads to the antenna principal beam attenuation, deflection and reflection. The design of radome for AESA radar for airborne applications is a major challenge due to its shape and size requirements. Very few pioneers in the world are developing this class of radomes. Manufacturing of these radome as per the design is another big challenge. Then it comes to the Electromagnetic (EM) characterization of the radome, for radar application this is an elaborate process as they are to be carried out are very high in number. The advantage of desired beam formation in AESA radar brings more complexity as the radiation patterns are different in transmission and reception. This paper presents the issues in design and development of low loss, high performance radomes for airborne AESA radars on fighter aircrafts. Also it focuses on the radome effects on AESA antenna main beam attenuation and side <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> lobe level degradation in Transmission and reception. The simulation and analysis of this kind of radomes is presented and discussed.

A multifunction phased array radar must search and track suspicious targets in its surveillance space in a real-time fashion. With inefficient scheduling implementations in many traditional systems, much radar resource is wasted with a very limited performance gain. This paper targets one of the most important issues in the design of modern phased array radars: real-time dwell scheduling. We formalize the typical workload of a modern phased array radar and propose a rate-based approach to schedule radar dwells in a real-time fashion. We show how to reserve radar resources to guarantee the minimum radar operation without sacrificing the stability of the system. The strength of our approach is verified by a series of simulation experiments based on a real phased array radar for air defense frigates [A. G. Huizing et al. (1996)]. A significant improvement in the performance of phased array radars was shown.

Radar is evolving rapidly from being a sensor which detects and tracks targets to a high resolution imaging sensor with target classification capabilities. This paper addresses the techniques being developed for air defence radars. The application of target classification functions in fire control radars which support missile systems and multi-function phased array radars is discussed. The main high resolution techniques employed are range profiling, ISAR, frequency/spectral analysis and range-frequency imaging. Typical aircraft images measured are presented. The level of maturity of the hardware and signal processing technology to support these modes is discussed. The key technical, operational and practical issues which drive the design and application of high resolution modes for these types of radars are presented. Factors which determine the type of target classification mode which can be employed include the: operational frequency of the radar, time available for the application of the high resolution waveform, pulse repetition frequency, radar bandwidth available, basic architecture of the radar, and mission of the radar system. The other critical issue for the practical employment of target classification modes is that of the target signature database. Classifier algorithms are used to provide the match between the signature measured by the radar and reference signatures of targets of interest held in a database to provide an estimate of the target class. The assembly and maintenance of the target signature database is discussed and techniques employed are presented.

Passive jamming is the significant pattern of jamming for Fire Control (FC) Radar. A comprehensive model is set up according to the respective characteristics of passive jamming and FC Radar in order to conduct quantitative analysis of FC Radar capabilities against passive jamming; the model is applied under given conditions of passive jamming to work out the FC Radar anti-jamming capabilities. It is therefore of certain applied value since the model accurately reflects real conditions by taking into account various factors affecting the FC Radar capabilities against passive jamming.

Novel acousto-optic systems for spectrum analysis and phased array radar signal processing are proposed. The pulsed source 2-D multiplicative time and space integrating spectrum analyzer is proposed and experimentally demonstrated. This architecture is simpler, physically smaller, and less sensitive to mechanical vibrations than the pulsed source 2-D additive Mach-Zehnder interferometer based spectrum analyzer. Simple and compact optical disk based systems for 1-D and 2-D spectrum analysis are presented. The high data packing density, angular motion, and parallel read out capability of optical disks is uniquely exploited to generate the very high time bandwidth product reference signals required for temporal spectrum analysis, that are otherwise difficult to generate using electronics. A continuous wave 1-D time integrating disk spectrum analyzer is successfully demonstrated in the laboratory. The limited dynamic range due to huge bias levels in interferometric time integrating processors is alleviated by using photorefractive crystals as real time bias removers. Continuous wave 1-D and 2-D bias free acousto-optic architectures for spectrum analysis are theoretically and experimentally investigated from a systems viewpoint. Simple, compact, and powerful acousto-optic systems for control and signal processing in phased array radars are proposed that eliminate many system components like phase shifters, mixers, power dividers, and complex antenna feed networks, that are encountered in typical electronically controlled phased array radars. Via a single control parameter, namely frequency, the optical technique provides appropriately phased signals for transmission and reception in phased array antennas. The system is capable of continuous beam scanning, simultaneous multiple beam formation, and multi-target tracking, and can be integrated on a substrate to provide smaller and lighter phased array radars. Also, the system is resistant to electromagnetic interference (EMI), and signal phase shifts are independent of the radar carrier frequency employed. A 1-D linear phased array radar acousto-optic beam steerer is successfully demonstrated in the laboratory, and performance issues such as detector phase sampling error and phase linearity are highlighted. The linear array design is extended to planar and multiple linear arrays.

This paper proposes a new method of beamforming for colocated MIMO radar with the coprime arrays. The proposed method splits the transmitting array into multiple overlapped subarrays and then transmits a coherent signal through each subarray, to achieve a maximum power in the desired direction. However, the signals from distinct subarrays are independent to preserve the diversity benefit of the MIMO radar. Thus, the proposed method exploits the advantages of both phased array and MIMO radars as well as the coprime arrays. Simulation results are presented to signify the beampattern and the signal to interference plus noise ratio performance of the proposed method and to compare with the earlier methods such as phased array radar, MIMO radar and the coprime MIMO radar.

In this paper, a system-specific phased-array radar system simulator was developed, based on a time-domain modeling and simulation method, mainly for system performance evaluation of the future Spectrum-Efficient National Surveillance Radar (SENSR). The goal of the simulation study was to establish a complete data quality prediction method based on specific radar hardware and electronics designs. The distributed weather targets were modeled using a covariance matrix-based method. The data quality analysis was conducted using Next-Generation Radar (NEXRAD) Level-II data as a basis, in which the impact of various pulse compression waveforms and channel electronic instability on weather radar data quality was evaluated. Two typical weather scenarios were employed to assess the simulator’s performance, including a tornado case and a convective precipitation case. Also, modeling of some demonstration systems was evaluated, including a generic weather radar, a planar polarimetric phased-array radar, and a cylindrical polarimetric phased-array radar. Corresponding error statistics were provided to help multifunction phased-array radar (MPAR) designers perform trade-off studies.

기존의 위상 배열 레이더는 인접한 안테나 단일 파형의 위상차를 이용하여 특정 방향으로 신호를 집중시키는 방식이다. 반면, MIMO(Multiple-Input Multiple-Output) 레이더는 다수 파형을 넓게 분포한 안테나를 통해 전송하는 방식이다. 이때, 다수의 파형과 넓게 분포한 안테나로부터 발생한 공간 다이버시티를 높은 SNR (Signal-Noise Ratio) 영역에서는 위상 배열 레이더보다 우수한 타켓 검출 성능을 보인다. 하지만, 낮은 SNR 영역에서는 신호를 집중시켜 어레이 이득을 얻는 위상 배열 레이더가 더 좋은 성능을 나타낸다. 본 논문에서는 MIMO 레이더에 위상 배열 안테나를 결합하여 다이버시티 이득과 어레이 이득을 모두 얻을 수 있는 지향성 MIMO 레이더의 검출 성능을 비교해 본다. 이와 더불어 실제 시스템에서 발생할 수 있는 지향각 오차에 대한 민감도가 성능에 미치는 영향을 분석허여, RF 장비의 수가 제한적이고 타켓 검출 성능이 제한적인 상황에서 각 레이더 성능을 비교하였다. In a traditional phased array radar, closely spaced antenna elements transmit a scaled version of single waveform to maximize the signal energy. On the contrary, a multiple-input multiple-output (MIMO) radar consists of widely separated antennas and transmits an arbitrary waveform from each antenna element. These waveforms and spatial diversity enable superior capabilities compared with phased array radar. At high signal-to-noise ratio (SNR), the detection performance of the MIMO radar is better than the phased array radar due to the diversity gains. However, the phased array radar outperforms the MIMO radar at low SNR, due to the energy maximization. In this paper, we investigate the compromised scheme between the MIMO radar and the phased array radar. Employing the MIMO radar equipped with phased array elements, the compromised scheme achieves both array gain and diversity gain. Also, we compare the performance degradation when the steering direction is incorrect.

Target Selection Algorithm for ASM using Modified ICP for Terminal Phase Applications

The growth of remote sensing by an airborne platform and the use of satellite communication from elliptical orbits indicate the need for a reflector antenna where the beamwidth of the main radiation pattern can be varied dynamically. The requirement is to make the radiated beam spot diameter independent of the antenna platform height and the scan angle. There are various other applications at microwave and millimetre wavelengths where a uniform footprint or precise changes in the beam spot diameter are required, for example, metrology from satellites, fire control radars and military communications. This paper describes a variable beamwidth dual reflector antenna which fulfils their specification. Parametric studies and an experimental verification of the concept are performed.

The accomplishments of the Signal Corps Laboratories in the development of radar are described with emphasis on the pre-World War II period. The development and evolution of early warning radar and fire control radar in the Army are treated in some detail. The ground radars used in combat during the war by the Army (including the Army Air Corps) are discussed.

A new Phased Array Radar (PAR) system for meteorological application has been developed by Toshiba Corporation and Osaka University under a grant of NICT, and installed in Osaka University, Japan in 2012. The PAR system has the unique capability of scanning the whole sky with 100 m and 10 to 30-second resolution up to 60 km. The system adopts the digital beam forming technique for elevation scanning and mechanically rotates the array antenna in azimuth direction within 10 to 30 seconds. The radar transmits a broad beam of several degrees with 24 antenna elements and receives the back scattered signal with 128 elements digitizing at each element. Then, by digitally forming the beam in the signal processor, the fast scanning is realized. After the installation of the PAR, SIP project has started to develop a new PAR with dual polarimetric capabilities, which was installed in Tokyo metropolitan area in 2017. Within the project, studies are being conducted to perform very short predictions of torrential rainfall events with deep neural networks.

Phased array antenna systems, which support high pulse rates and high transmit power, are well suited for radar and large-scale surveillance. Sensors and communication systems can function as the eyes and ears for ballistic missile defense applications, providing early warning of attack, target detection and identification, target tracking, and countermeasure decision. In such applications, active array radar systems that contain solid-state transmitter sources and low-noise preamplifiers for transmission and reception are preferred over the conventional radar antennas, because the phased array radar offers the advantages of power management and efficiency, reliability, signal reception, beam steering target detection. The current phased array radar designs are very large, complex and expensive and less efficient because of high RF losses in the phase control circuits used for beam scan. Several thousands of phase shifters and drivers may be required for a single system thus making the system very complex and expensive. This paper describes the phased array radar system based on high power T/R modules, wide-band radiating planar antenna elements and very low loss wide-band phase control circuits (requiring reduced power levels) for beam scan. The phase shifter design is based on micro-strip feed lines perturbed by the proximity of voltage controlled piezoelectric transducer (PET). Measured results have shown an added insertion loss of less than 1 dB for a phase shift of 450 degrees from 2 to 20 GHz. The new wideband phased array radar design provides significant reduction in size cost and weight. Compared to the conventional phased array systems, the cost saving is more than 15 to 1.

Phased array radar has been applied broadly because of its sound performance. But signal of phased array radar is of a wide variety of types. Therefore, recognition of phased array radar is the most puzzling aspect of the whole emitter identification domain. To solve the problem, the article proposes the method that identifies phased array radar by pulse amplitude information, and studies the phased array radar, models transmit signal of them, and receiving signal by radar countermeasure reconnaissance receiver. From constructing template of pulse train’s amplitude vector of mechanical scanning radar, computing distance of samples and standard template, finding threshold of the template matching arithmetic, the article puts forward the template matching algorithm of radar beam scan type recognition to identify phased array radar automatically.