Developments in Antenna Analysis and Design: Volume 2
Developments in Antenna Analysis and Design presents recent developments in antenna design and modeling techniques for a wide variety of applications, chosen because they are contemporary in nature, have been receiving considerable attention in recent years, and are crucial for future developments. It includes topics such as body-worn antennas, that play an important role as sensors for Internet of Things (IoT), and millimeter wave antennas that are vitally important for 5G devices. It also covers a wide frequency range that includes terahertz and optical frequencies. Additionally, it discusses topics such as theoretical bounds of antennas and aspects of statistical analysis that are not readily found in the existing literature. This second volume covers the topics of: graphene-based antennas; millimeter-wave antennas; terahertz antennas; optical antennas; fundamental bounds of antennas; fast and numerically efficient techniques for analyzing antennas; statistical analysis of antennas; ultra-wideband arrays; reflectarrays; and antennas for small satellites, viz., CubeSats. The first volume covers the theory of characteristic modes (TCM) and characteristic bases; wideband antenna element designs; MIMO antennas; antennas for wireless communication; reconfigurable antennas employing microfluidics; flexible and body-worn antennas; and antennas using meta-atoms and artificially-engineered materials, or metamaterials (MTMs). The two volumes represent a unique combination of topics pertaining to antenna design and analysis, not found elsewhere. It is essential reading for the antenna community including designers, students, researchers, faculty engaged in teaching and research of antennas, and the users as well as decision makers.
Inspec keywords: antennas
Other keywords: graphene-based antennas; optical antennas; small satellites antennas; fast numerically efficient techniques; reflectarrays; fundamental bounds; millimeter-wave antennas; modeling techniques; terahertz antennas; antenna design; statistical analysis; CubeSats; ultra-wideband arrays
Subjects: Antennas; General electrical engineering topics
- Book DOI: 10.1049/SBEW543G
- Chapter DOI: 10.1049/SBEW543G
- ISBN: 9781785618901
- e-ISBN: 9781785618918
- Page count: 426
- Format: PDF
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Front Matter
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1 Terahertz antennas, metasurfaces and planar devices using graphene
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Graphene is expected to be an enabling technology for THz antennas and related devices. This chapter describes the foundations for the theoretical and numerical modeling of graphene devices in the framework of Maxwell's equations. Subsequently, several designs of graphene planar antennas for terahertz frequencies are proposed showing that high-quality-gated graphene can be used to achieve frequency reconfiguration in resonant plasmonic antennas and beam steering in graphene-based-plasmonic reflectarrays. Afterwards, the potential of graphene for non-reciprocal applications is demonstrated experimentally, with the design, fabrication, and measurement of the first terahertz graphene isolator (operating between 1 and 10 THz). Finally, preliminary results concerning the realization of graphene beam steering reflectarray antennas at terahertz frequencies are presented. All of the above takes advantage of a newly developed theoretical “upper bound”which allows one to evaluate the closeness of a given design to the theoretical optimum, and depends uniquely on graphene conductivity.
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2 Millimeter-wave antennas using printed-circuit-board and plated-through-hole technologies
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In this chapter, we presented three different design methodologies for MMW antennas targeted to work at the upper bands of the 5G communications, namely, 57-64 GHz and 57-71 GHz, using PCB and PTH technologies. The key design philosophy is to employ available technologies and materials to the farthest extent and then make use of the design to satisfy the required specifications. The antennas are: wideband MMW ME dipole antennas, the HOM MMW patch antenna, and wideband MMW complementary source antennas.
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3 THz photoconductive antennas
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In this chapter, the theoretical modeling, numerical simulation and experimental study of PCA are thoroughly discussed. The principles of three representative models, namely, Drude-Lorentz model, equivalent circuit model and full-wave model, were introduced. After summarizing the pros and cons of each model, the full-wave model was chosen for numerical simulation of PCA, as it has least physical assumptions and thus should be the most accurate. The numerical simulation was carried out using in-house codes on the MATLAB® platform, which was also verified using commercial software. The radiation properties of a PCA were then thoroughly studied by varying several important parameters, such as laser power, bias voltage, photoconductor material properties and laser pulse width. To demonstrate the application of this model, two new PCAs were designed and simulated, and enhanced THz radiations were predicted for both. The influences of the photoconductive material, antenna structures, etc. on the THz radiation power and bandwidth are systematically investigated to gain a more comprehensive understanding of a PCA. The general radiation mechanism of the PCAs is further studied by implementing the polarization effect and cancellation effect measurements. Recent progresses of the PCA structure development using nanostructure and plasmonic antenna electrodes to improve the THz radiation power/efficiency are briefly reviewed. In addition, the THz near-field spectroscopic technique based on PCAs is proposed to overcome the resolution limit and achieve sub-wavelength resolution. Specifically, incorporating the Hadamard multiplexing method with an emitter array for the THz near-field configuration, the system SNR is enhanced, agreeing well with theoretical prediction. With more array elements, the system SNR can be further improved. Various THz applications are explored utilizing the far-field and near-field THz-TDS setup, including material characterization, imaging and sensing. With the advancement of THz far-field and near-field systems incorporating PCAs in recent years, more innovative and practical THz applications will be enabled.
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4 Optical antennas
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Optical antennas are at the crossroads of photonics, material sciences and antenna engineering. Advances in electromagnetic modelling methods, in material science and in nanofabrication techniques have enabled tremendous achievements by researchers and technologists worldwide. The interest in nanoantennas has been largely fuelled by promises of real-world optical applications for which access to resolving subwavelength features is highly desired. Such applications include localised field enhancement, ultra-fast detection and sub-diffraction sensing. Furthermore, concepts of optical components inspired by reflectarrays, transmitarrays and metasurfaces have emerged to offer fine manipulation of optical beams at a subwavelength scale. As these developments mature and find their ways into future technologies, a new field of applications are emerging. The aim of this chapter is to introduce the fundamental concepts relevant to the understanding of optical antennas and provide a (non-exhaustive) review of recent developments.
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5 Fundamental bounds and optimization of small antennas
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This chapter reviews the use of fundamental bounds and the Q-factor in small antenna optimization. With the fundamental bounds, the antenna designer can estimate how well the antenna will perform before the design process. This can provide insight if the design specifications can be met with the structure at hand. Moreover, knowledge of the antenna's bounds can be used in a physical limitation-aware optimization, where the optimization process can be terminated once the target is achieved with a certain margin. Formulating the bounds as a convex optimization problem offers the flexibility to add additional “convex” constraints with minor effort. Examples of additional constraints include limitations on efficiency, SAR, and the radiation pattern or optimizing the antenna region of embedded antennas. The antenna designer can investigate numerous situations by adding the previous constraints to the original convex problem. The introduction of a method to estimate Q(Z') of antennas from the current distribution computed for a single frequency; the application of fundamental bounds and of the Q(Z') single-frequency estimation method to design cases of three-dimensional radiating structures has not been considered previously in the literature. The results suggest that customized physical bounds, optimum currents, and single-frequency expressions are tools that are useful for antenna design, e.g., to stop an optimization process, assess realizability of specifications, and assess performance of antenna locations. While the examples in this chapter considered PEC material, the optimization can be extended to antennas consisting of composite materials such as PEC and dielectrics.
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6 Fast analysis of active antenna systems following the Deep Integration paradigm
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The ultimate form of system integration is arguably to fuse conducting, semiconducting, and non-conducting materials into a single heterogeneous material having the multifunctional properties of a full-blown antenna system. This chapter introduces the so-called Deep Integration paradigm and discusses the fast numerical analysis of these potentially next-generation deeply integrated antenna structures. These multiscale problems are analyzed efficiently through a numerical enhancement technique, called the Characteristic Basis Function Method.
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7 Numerically efficient methods for electromagnetic modeling of antenna radiation and scattering problems
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We describe several numerical techniques for electromagnetic modeling of large and complex antenna problems, which require a large number of DoFs to describe them, and hence, they are CPU time- and memory-intensive when conventional methods are used to tackle them. We describe the characteristic basis function method (CBFM) as well as the integral equation discontinuous-Galerkin technique (IEDG) for the handling of these type of problems numerically efficiently. The details of the formulations are presented and numerical examples given to validate them. For many practical applications, not only the antenna problems are of interest when they operate in either transmit or receive mode, but also when we need to design them to have a low RCS, as is frequently the case in practice. We point out that the methods described in this work are quite general and are well suited for all of these cases. Furthermore, they can be used to model antennas with arbitrary material properties, be they lossy or lossless. We also present three types of sources as excitations for generating the CBFMs for the microwave circuit and antenna problems, as opposed to RCS. We conclude that the near-field contents of the edge-port and dipole moment excitations can enhance the accuracy of the CBFM over the plane wave excitation.
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8 Statistical electromagnetics for antennas
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After a brief introduction, this chapter discusses the state of the art of variable antennas and previous works on these antennas are reviewed. This is followed by an introduction to the most common statistical analysis techniques used for the purpose of the uncertainty propagation. The application of the statistical method to some real case structures is then considered; split ring resonator (SRR) and wearable antennas.
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9 Ultra-wideband arrays
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In this chapter, we focus on these modern challenges faced by wideband array designers, and the substantial advancements which have been made over the past 5 years. Initially, we provide a review of UWB array designs to familiarize the reader with the two most common groups of UWB arrays. These are developed with an overview of their basic principles, practical design considerations, and illustrative examples from the literature. Thereafter, we delve into the particular challenges associated with designing these arrays for the emerging applications at millimeter-wave frequencies.
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10 Reflectarray antennas
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The principal concepts of reflectarray antennas have been reviewed in this chapter. Reflectarrays have shown several advantages with respect to reflector and phased-array counterparts. Reflectarrays have demonstrated their capability to produce shaped beams, independent beamforming in each polarization, multi-frequency operation, among others. The limited bandwidth has been significantly overcame by different techniques, including the development of multi-resonant broadband cells and compensation of the spatial phase delay. Different contributions to the state of the art in the topic of reflectarrays for fixed and reconfigurable beams have been presented, including a large variety of the reflectarray cells proposed to improve the antenna performance using different technologies. Some selected recent and ongoing developments have been summarized. Examples such as contour-beam and multibeam reflectarrays, steerable-beam reflectarrays, dual-reflector antennas, reflectarrays in solar panels and deployable and inflatable reflectarrays have been presented. Finally, some challenging technologies and materials, such as 3-D printing, liquid crystals or graphene, can be very promising for future applications in terahertz. The results presented here show a great potential of reflectarrays for passive and reconfigurable antennas in a large range of frequencies from microwaves to terahertz and even optical frequencies.
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11 Novel antenna concepts and developments for CubeSats
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A miniaturized class of satellites called SmallSats, whose weight are typically under 500 kg, has recently garnered significant attention to exploit space for many applications. A key member of the SmallSat family are CubeSats. CubeSats can weigh as little as 1.33 kg with a volume as small as 10 x 10 x 10 cm3. Realizing the potential of CubeSats, the scientific community is revisiting existing spacecraft technologies to enable their integration with the small CubeSat form factor [1,2]. This chapter particularly focuses on the antenna research and development. We review the general constraints that antenna engineers face while designing antenna systems for CubeSats. An extensive literature collection is presented to survey the current state of the art in antenna systems for CubeSats. We also discuss recent antenna research that enables many exciting missions in the future.
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Back Matter
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