Reliability analysis for phased array radar systems

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.

In this paper, we propose an interference alignment (IA) method for interference elimination in co-existing Phased Array (PA) radar and multi-user multiple-input multiple-output (MIMO) communication systems. Although ergodic IA method has been proposed to cancel the mutual interferences, it will definitely reduce the degrees-of-freedom (DoFs) of communication systems. Differently, our proposed IA method allows to improve the DoFs. It is examined by the Neyman-Pearson (NP) test for radar functionality, while the communication performance is evaluated by DoFs and bit error rate (BER) analysis. Both theory analysis and numerical results are provided to validate the effectiveness of the proposed IA method.

Phased array radar systems are used for a wide variety of applications including the precise tracking of airborne craft for air traffic control and providing accurate atmospheric condition information important in weather forecasting. Reducing the cost and size of these radar systems will open new fields to the use of this technology. Using phase control implemented through liquid crystal materials we have created a compact, phased array radar system operating in the microwave range. We report on the construction and testing of a linear, eight element phased array antenna system operating at 32 GHz with element phase controlled by a dual frequency nematic liquid crystal media used as a tunable dielectric. The system was designed using CST Design Studios and Ansys HFSS software. Dual frequency liquid crystals are used to improve beam steering response times. We demonstrate 42 millisecond beam switching times, defined as the time to change the beam focus from one point to another point, controllable beam formation, and beam steering profiles consistent with analytical results and simulation models. The device footprint is a square with sides 9.5 cm long and a thickness less than 2.5 mm. Such a module is easily stackable to create an 8 × 8 phased array system. Our design incorporates a modular construction using PCB for the antennas and input circuitry and a liquid crystal phase control cell with microwave glass substrates. This design simplifies design, construction, and testing as compared to on-glass designs. The device shows an improvement in point-to-point scanning speeds by a factor of 3 as compared to similar liquid crystal based devices and provides continuously variable tuning. Such a device can be used in a system for reduced visibility, directional range finding suitable for automobile collision avoidance systems and rotary wing aircraft landing aids.

Performance and Reliability Analysis of Computer Systems: An Example-Based Approach Using the SHARPE Software Package provides a variety of probabilistic, discrete-state models used to assess the reliability and performance of computer and communication systems. The models included are combinatorial reliability models (reliability block diagrams, fault trees and reliability graphs), directed, acyclic task precedence graphs, Markov and semi-Markov models (including Markov reward models), product-form queueing networks and generalized stochastic Petri nets. A practical approach to system modeling is followed; all of the examples described are solved and analyzed using the SHARPE tool. In structuring the book, the authors have been careful to provide the reader with a methodological approach to analytical modeling techniques. These techniques are not seen as alternatives but rather as an integral part of a single process of assessment which, by hierarchically combining results from different kinds of models, makes it possible to use state-space methods for those parts of a system that require them and non-state-space methods for the more well-behaved parts of the system. The SHARPE (Symbolic Hierarchical Automated Reliability and Performance Evaluator) package is the `toolchest' that allows the authors to specify stochastic models easily and solve them quickly, adopting model hierarchies and very efficient solution techniques. All the models described in the book are specified and solved using the SHARPE language; its syntax is described and the source code of almost all the examples discussed is provided. Audience: Suitable for use in advanced level courses covering reliability and performance of computer and communications systems and by researchers and practicing engineers whose work involves modeling of system performance and reliability.

This paper describes the design and implementation of an X-band scalable $4\times 4$ element-level digital phased array module. The module consists of sixteen active antenna elements. Each of these elements includes one custom CMOS RF SoC and one custom GaAs switch frontend IC. The RF SoC is implemented using a 65-nm CMOS process. The T/R Switch frontend IC is implemented in a $0.15-\mu \mathrm{m}$ GaAs pHEMT process. The module also includes a digital signal processor implemented in an FPGA SoC device, and the required power supply subsystems. This module can be used to build a large hierarchical digital phased array through synchronizing four LO signals at system level. The built array serves as a tool for researching software-defined phased array radar and communication systems. This paper reports initial test results of this module. This module achieves a state-of-the-art 42-mm scalable tile thickness.

In spite of the major recent advances in the phased array radar and communication systems, calibration in general is still a major challenge. In this work, a quasi-near-field fixed probe based calibration framework is proposed, which is capable of ‘One-Shot’ calibration without any system downtime for digital phased array. Both theory and mathematical model has been developed for different error sources. The error evaluation relative to ‘ground-truth’ has been demonstrated for calibration purpose.

In the following paper an X-band hybrid electro optical mixer for a photonic microwave receiver is described. The application of balanced hybrid mixer in phased array radar, communication system and ESM receivers will reduce overall loss and hence the cumulative noise figure of the system and thus enhance the spurious free dynamic range of the receiver.

Phase linear characteristic is an important parameter of RF transceiver module in phased array radar system. This paper analyzes the causes of phase nonlinear based on the mechanism of which, and puts forward four methods of optimizing the phase linear. Finally, an X-band RF transceiver module is designed and manufactured to verify the effectiveness of the methods. The test results show that by using the methods proposed, the phase distortion of the RF transceiver module can be improved obviously.

In this study, a new approach is proposed for accurate target identification, required by the phased array radar systems that are employed in through‐the‐wall imaging applications. In radar imaging, the effects of the multipath propagation are materialised in fake impressions of the true target, known as ghost images. The developed algorithm removes these ambiguities related to the existence of a target by cancelling, in the final radar image, the ghost images by means of improving the global signal‐to‐spurious‐ratio (SSR) and the target‐to‐ghost‐ratio (TGR) that characterise the real target signature. The development of the approach is based on beamforming and on coherent signal processing upon the returned signal and clutters, for a phased array monostatic radar system. The performances of the algorithm are measured in terms of both the global SSR gain and the TGR and they are verified through simulations and measurements in scenarios that quantify the robustness of the approach. The obtained numerical results concerning the global SSR gain and the TGR certify that the proposed method improves the target localisation and removes the ghost images for radars that operate in rich scattering environments. In the end, the limitations of the approach are also presented.

Use of multiple transmit and receive antennas have become a popular research area in radar community after the success of the same concept in communication. It is shown by Fishler et al. that multi-input multi-output (MIMO) radar has considerable advantages compared to traditional radar and phased array radar systems. In this paper, detection performance of MIMO radar using Neyman-Pearson detector is investigated in K-distributed sea clutter for a practical scenario. Also, spikiness of K-distributed MIMO radar clutter is discussed with respect to the number of nodes.

In this paper, a joint revisit and dwell time management (JRDTM) strategy for single target tracking based on the predicted Bayesian Cramer-Rao lower bound (BCRLB) in phased array radar system is addressed. We achieve the time resources management by formulating and solving an optimization problem, which is to minimize the resource amount used for tracking with the tracking accuracy of the target meeting a predesigned threshold. As the BCRLB provides a lower bound on the estimated mean square error (MSE) of target state, the predicted BCRLB model with time resources is derived and employed as the metric for the tracking performance. We put forward a converted algorithm to settle the optimization problem subsequently. Simulation results demonstrate that the proposed joint management strategy can help to achieve the tracking performance with less resource consumed.

Reliability Block Diagrams (RBDs) allow us to model the failure relationships of complex systems and their sub-components and are extensively used for system reliability, availability, dependability and maintainability analyses of many engineering systems. Traditionally, Reliability Block Diagrams (RBD) are analyzed using paper-and-pencil proofs or computer simulations. Recently, formal techniques, including Petri Nets and higher-order-logic theorem proving, have been used for their analysis as well. In this paper, we provide a concise survey of these available RBD analysis techniques and compare them based on their accuracy, user friendliness and computational requirements.

This paper describes a MMIC that has been designed using the GMMT Medium Power Foundry process which produces 5.4 Watts of power at 9.2 GHz with a PAE of 22%. Integral heatsink technology and power circuit design techniques have facilitated the design of a compact, densely packed circuit occupying 20 mm/sup 2/ of GaAs. The small signal gain of the MMIC is 16 dB, with a 10 dB input match from 9 to 11 GHz. This MMIC is suitable for many X-band applications such as communications networks and safety radiolocation systems, but its high pulsed power output and low phase-gain distortion make it particularly ideal for use in phased array radar systems.

Phased array radar systems, which emerged over 55 years ago, have continually evolved from the early 60s to present day. Over 55 years ago, U.S. phased array radar systems brought a new dimension or capability that is fully realized in today's all-solid-state arrays, such as those on the F-22 and F-35 military aircraft. This process of expanding phased array capability involved an evolutionary series of steps each decade. This paper cites the most prominent U.S.-deployed phased array radars as viewed by one phased-array radar advocate.

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.