Maurizio Bozzi
In view of the practical significance of high-resolution microwave imaging in global change monitoring, natural resource investigation, ecological environment protection, smart city construction, disaster emergency response, national defense, and security construction, I am delighted to introduce readers to this remarkable book on high-resolution microwave imaging. It stands as the pioneering work on active array antennas in the imaging radar domain. This monograph has three important features.
The first objective is to conduct extensive research on metal-based waveguide active array antennas, meticulously analyzing and studying the discontinuity of electromagnetic signal distribution, synthesis, transmission, filtering, and excitation in the cylindrical waveguide pertaining to the waveguide active array antennas. The book presents a comprehensive theoretical model and design methodology encompassing field mode cancellation suppression and wide-angle scanning matching as well as coupling the matching of electromagnetic fields, structural mechanics fields, and temperature fields. It introduces novel structures such as complementary superposition waveguide coupling, filter feeding, polarization control slots, shared-aperture nesting, complementary radiation, and other cutting-edge concepts. Additionally, it explores the 3D integrated architecture and implementation methods for multipolarization and multiband waveguide active array antennas, paving the way for traditional waveguide antennas to achieve high efficiency, low profile, and multipolarization/multiband shared-aperture active arrays.
The second aspect addresses the inherent characteristics of traditional active array antennas, which include long analog/RF signal links and significant amplitude and phase errors resulting from space–time–frequency variations. This monograph extensively investigates and analyzes new configurations and implementation methods for multiband broadband digital arrays and RF optical transmission synthetic apertures. It delves into the precise modeling of wideband digital arrays and optical control array systems in various domains, namely the space domain, frequency domain, time domain, temperature domain, and polarization domain. Furthermore, it examines measurement and compensation methods for broadband linear frequency modulated signals and fractional delay filters, offering innovative research ideas to enhance beam pointing and beamforming accuracy in active array antennas.
The third aspect aims to address the evolving demands of high-resolution microwave imaging radar. This monograph introduces a groundbreaking concept known as the antenna array microsystem. In the post-Moore era of integrated circuits, active array antennas are anticipated to integrate an increasing number of active and passive circuits, forming an active array antenna microsystem. Drawing upon electromagnetic fields, microelectronics, optoelectronics, materials science, and thermodynamics, along with system architecture and electromechanical and thermal multiphysics models, the book advocates for a distributed and open architecture approach. Leveraging heterogeneous and hybrid integration technologies and methods, the proposed approach enables the 3D heterogeneous integration of antenna arrays, organic source transceiver channels, power distribution/synthesis networks, frequency synthesis, beam steering, receivers, power supplies, and heat conduction structures. At the hardware level, it emphasizes deep cross-integration, architecture optimization, functional hardware in chips, and vertical interconnections of high-density and low-consumption signals to realize software and hardware integration. This approach facilitates scalability, up/down compatibility, resource collaborative allocation, intelligence, reliability, multifunctionality, low cost, and highly integrated lightweight active array antenna microsystems. Undoubtedly, the new idea of the active antenna array microsystem delineates the development trajectory for active array antennas.
This book delves into the intricate technical challenges of the “invisible and indistinguishable” nature encountered in high-resolution microwave imaging radar for Earth observation. It focuses on the fundamental aspects of “frequency and polarization” and thoroughly explores the application of active array antennas in the analysis, optimization, and design of high-resolution microwave imaging radar. Beginning with an in-depth discussion of the basic principles, analysis methods, and performance parameters of active array antennas, the book systematically elucidates the achievement of low-profile, highly efficient, and lightweight antennas. It provides a comprehensive examination of the architecture, analysis methods, and engineering practices for realizing broadband, multiband, and multipolarization capabilities in active array antennas. This encompasses cutting-edge technologies such as digital array antennas, microwave photonic array antennas, active package antennas, and other significant advancements. The main contents of the book encompass the following key areas.
Chapter 1, “Introduction,” provides a comprehensive overview, delving into the distinguishing features of high-resolution microwave imaging radar and active array antennas. It traces the evolutionary trajectory of antennas, encompassing the development history of semiconductor integrated circuits and hybrid integrated circuit technology along with their significant applications in active array antennas. The chapter introduces a groundbreaking concept, namely the antenna array microsystem, and engages in a thorough exploration of emerging technologies and future directions for active array antennas, presenting a compelling vision for their advancement.
Chapter 2, “Array Antenna Analysis and Optimization,” initiates with a fundamental exploration of array antennas, elucidating the basic concepts and introducing two crucial types of characteristic parameters related to antenna ports and radiation. Considering the specific requirements of microwave imaging applications, the chapter delves into the design methodologies, progressing from linear arrays to planar arrays and even sparse array configurations, thoroughly examining their constituent elements. Furthermore, it conducts a detailed analysis and discussion on beamforming optimization techniques, encompassing both phase weighting and advanced approaches involving amplitude/phase weighting. By addressing these key aspects, the chapter equips readers with essential insights into the analysis and optimization of array antennas for optimal performance in microwave imaging applications.
Chapter 3, “Array Antenna Error and Compensation,” takes an engineering design approach to thoroughly analyze the errors that can arise in active array antennas and the corresponding compensation methods. It investigates the impact of these errors on the radiation characteristics of the antenna. Building upon this foundation, the chapter introduces synthesis and analysis methods for antenna patterns and delves into error correction and compensation techniques specifically tailored for phased array antennas. Additionally, it explores antenna measurement technologies and provides insights into rapid measurement and precise modeling techniques for 2D phased array antennas used in microwave imaging radar. By addressing these critical aspects, the chapter equips readers with the necessary knowledge and techniques to mitigate errors and optimize the performance of active array antennas in microwave imaging applications.
Chapter 4, “Broadband Active Array Antennas,” delves into the mechanisms that constrain the instantaneous bandwidth of active array antennas, examining factors such as antenna beam pointing deviation, aperture transit time, and signal frequency modulation rate. It analyzes and discusses the configuration of real-time delay lines in 1D and 2D active array antenna systems. Furthermore, the chapter provides an in-depth exploration of the fundamental principles, classification, performance parameters, and characteristics of microwave delay components. It offers detailed insights into the design methodologies and experimental findings related to common microwave delay components. By addressing these aspects, the chapter equips readers with a comprehensive understanding of wideband active array antennas, enabling them to overcome bandwidth limitations and optimize the performance of these antennas in diverse applications.
Chapter 5, “Active Array Module Integration,” covers how the integration of active array modules serves as a fundamental pillar for achieving low-profile, high-efficiency, and lightweight active array antennas. Building upon an analysis and discussion of integrated architectures for active arrays, this chapter provides an exploration of the composition, basic principles, design methods, and integration technologies of “tile” active array modules. It delves into the intricate challenges associated with the miniaturization of transceiver components and the 3D heterogeneous integration methods for chip-scale integration. Moreover, the chapter presents notable research findings and exemplary results pertaining to active array modules. By delving into these crucial aspects, readers gain valuable insights into the integration processes that underpin the development of high-performance active array antennas, facilitating their realization of compact form factors, increased efficiency, and reduced weight.
Chapter 6, “Shared-Aperture Array Antennas,” explores the requirements and implementation methods for wideband, multiband, and multipolarization shared-aperture antennas. It places special emphasis on the design techniques for two types of dual-wire/circularly polarized shared-aperture antennas, specifically microstrip and waveguide antenna designs. Building upon this foundation, the chapter introduces the latest research and development advancements in three-band dual-polarized shared-aperture antennas. By delving into these crucial aspects, readers gain comprehensive insights into the design considerations, techniques, and cutting-edge developments in shared-aperture array antennas.
Chapter 7, “Active Antenna-in-Package Arrays,” focuses on the technological advancements in active antenna-in-package (AiP) arrays, which represent an intermediate form between active array antennas and antenna array microsystems. It begins by introducing the classification of AiPs and broadband AiP units. Furthermore, it delves into the analysis of coupling and mutual interference mechanisms of multiple physical quantities at a microscale, investigating the parasitic effects resulting from the interactions between various parameters. The chapter explores multilayer vertical interconnection technologies such as button interconnection, inter-board ball grid array interconnection, inter-board land grid array interconnection, intra-board interlayer interconnection, and inter-chip through-silicon via interconnection. Additionally, it examines the use of embedded devices to achieve the miniaturization and lightweight characteristics of microwave passive devices. The chapter provides detailed insights into three AiP materials and process technologies, namely low-temperature cofired ceramic, high-temperature cofired ceramic, and organic matter. Furthermore, it presents a research result involving a millimeter-wave 64-element AiP array. By delving into these critical aspects, the chapter equips readers with comprehensive knowledge of the advancements in active AiP arrays, including the integration of multiple technologies, materials, and processes to achieve compact and lightweight AiPs.
In Chapter 8, “Digital Array Antennas,” based on the outstanding advantages of a digital array microwave imaging radar system, such as high dynamics, a low antenna sidelobe, and high beam scanning precision, the chapter introduces the basic principles of digital array antennas, such as phase accumulator, phase/amplitude converter, direct digital synthesis (DDS), DDS spectrum characteristic analysis, the digital signal generation technology of the DDS spurious suppression method, and digital receiving technology, such as digital sampling and digital downconversion. The technical approach of reducing the noise figure of the digital array antenna system and improving the dynamic range of the system is studied, the design idea of a distributed frequency source beyond the traditional frequency synthesizer is proposed, and the research results of application examples are given.
Chapter 9, “Microwave Photonic Array Antennas,” covers microwave photonic technology, representing an emerging field that merges microwave and photonic technologies. This chapter explores the application of microwave photonic technology in antenna arrays, focusing on two distinct areas: microwave photonic digital array antennas and optically controlled phased array antennas. Microwave photonic technology is an emerging technology that combines microwave technology and photonic technology. According to the functional differences of microwave photonic technology in antenna arrays, microwave photonic digital array antennas and optically controlled phased array antennas are studied and analyzed, and the basic principles and implementation methods of the optical real-time delay of active array antennas, microwave signal modulation and demodulation, optical analog-to-digital conversion, and microwave photon filtering are elaborated. The basic characteristics of microwave photonic devices commonly used in microwave photonic links are introduced, and the main performance parameters, such as noise source, noise figure, dynamic range, isolation, and insertion loss in microwave photonic links, are discussed.
From a comprehensive standpoint, this monograph embarks on a systematic exploration of array antennas, beginning with the foundational theory and progressing through various key aspects. It provides a thorough description of the analysis and optimization of array antennas, delving into the intricacies of error detection and compensation techniques. The book further examines wideband active array antennas, shared-aperture array antennas, active package array antennas, and digital array antennas. It goes beyond conventional approaches by exploring cutting-edge technologies such as microwave photonic array antennas and active array module integration. By presenting these topics in a coherent and interconnected manner, the monograph enhances readers’ comprehension of high-resolution microwave imaging active array antennas. Moreover, it serves as a valuable resource for expanding readers’ academic horizons, enabling them to delve into advanced concepts and emerging research areas in the field.
From a practical standpoint, this monograph represents the culmination of more than three decades of dedicated involvement in the development of high-resolution microwave imaging radar. It stands as a testament to the authors’ extensive theoretical expertise and wealth of practical experience in the field. This comprehensive work serves as a valuable resource for radar antenna researchers, providing valuable guidance for their engineering design endeavors. With its solid theoretical foundation and the wealth of practical insights contained within its pages, the monograph offers invaluable support to researchers, equipping them with the knowledge and tools necessary to navigate the complexities of radar antenna design.
From the point of view of innovation, in response to the development needs of high-resolution microwave imaging radar, the monograph puts forward a new concept of “an active array antenna microsystem,” which integrates multiple disciplines such as microwave devices, electromagnetic fields, microelectronics, materials, and integrated processes. The design, experimental verification, and development of the active array antenna are described.
This book serves as an invaluable teaching reference for senior undergraduates and postgraduates specializing in radar, communication, microwave, and antenna disciplines. Its comprehensive content and in-depth exploration make it a valuable resource for academic instruction. Additionally, both professionals engaged in scientific research and engineering technicians will find this book to be a valuable reference in their respective fields. The extensive knowledge and practical insights offer guidance and support for ongoing research endeavors and engineering projects. Whether used as a teaching aid or a reference manual, this book caters to the needs of a wide range of readers, fostering both academic growth and professional development.
Digital Object Identifier 10.1109/MMM.2023.3307888