Analysis And Design Of Reflectarrays Transmitarrays Antennas

This book provides engineers with a comprehensive review of the state-of-the-art in reflectarray antenna research and development. The authors describe, in detail, design procedures for a wide range of applications, including broadband, multi-band, multi-beam, contour-beam, beam-scanning, and conformal reflectarray antennas. They provide sufficient coverage of basic reflectarray theory to fully understand reflectarray antenna design and analysis such that the readers can pursue reflectarray research on their own. Throughout the book numerous illustrative design examples including numerical and experimental results are provided. Featuring in-depth theoretical analysis along with practical design examples, em style="mso-bidi-font-style: normal;"Reflectarray Antennas is an excellent text/reference for engineering graduate students, researchers, and engineers in the field of antennas. It belongs on the bookshelves of university libraries, research institutes, and industrial labs and research facilities.

In recent years, transmitarray antennas have attracted growing interest with many antenna researchers. Transmitarrays combines both optical and antenna array theory, leading to a low profile design with high gain, high radiation efficiency, and versatile radiation performance for many wireless communication systems. In this book, comprehensive analysis, new methodologies, and novel designs of transmitarray antennas are presented. Detailed analysis for the design of planar space-fed array antennas is presented. The basics of aperture field distribution and the analysis of the array elements are described. The radiation performances (directivity and gain) are discussed using array theory approach, and the impacts of element phase errors are demonstrated. The performance of transmitarray design using multilayer frequency selective surfaces (M-FSS) approach is carefully studied, and the transmission phase limit which are generally independent from the selection of a specific element shape is revealed. The maximum transmission phase range is determined based on the number of layers, substrate permittivity, and the separations between layers. In order to reduce the transmitarray design complexity and cost, three different methods have been investigated. As a result, one design is performed using quad-layer cross-slot elements with no dielectric material and another using triple-layer spiral dipole elements. Both designs were fabricated and tested at X-Band for deep space communications. Furthermore, the radiation pattern characteristics were studied under different feed polarization conditions and oblique angles of incident field from the feed. New design methodologies are proposed to improve the bandwidth of transmitarray antennas through the control of the transmission phase range of the elements. These design techniques are validated through the fabrication and testing of two quad-layer transmitarray antennas at Ku-band. A single-feed quad-beam transmitarray antenna with 50 degrees elevation separation between the beams is investigated, designed, fabricated, and tested at Ku-band. In summary, various challenges in the analysis and design of transmitarray antennas are addressed in this book. New methodologies to improve the bandwidth of transmitarray antennas have been demonstrated. Several prototypes have been fabricated and tested, demonstrating the desirable features and potential new applications of transmitarray antennas.

This book addresses the design and analysis of different reflectarrays and transmitarray antennas to meet these requirements. A reflectarray is made up of an array of radiating elements that provide a preadjusted phasing to form a focused beam when it is illuminated by a feed, in a similar way to a parabolic antenna. Printed reflectarrays combine certain advantages of reflector antennas and phased arrays. The reflectarray antennas design in this work includes five antennas. The second part in this book discus five designs of the transmitarray. The first transmitarray is single layer transmitarray antenna using rectangular dielectric resonator as the unit cell elements. Two different constructions for the unit cell of the transmitarray are used.The transmitarray is a multilayer dielectric resonator antenna transmitarray for fixed RFID reader applications is presented at 5.8 GHz. A circularly polarized 9x9 square DRA transmitarray is designed at 5.8 GHz for far-field RFID applications. A design of 9x9 near-field focused DRA transmitarray for fixed RFID at 5.8 GHz is investigated. The properties of the NF-focused transmitarray are compared with the far field transmitarray designed.

Reflectarray antennas refer to the class of radiating structures that are comprised of an array of radiating elements, re-radiating the energy that is impinged on them from one or more radiating feeds that are located in free space. The constituent radiators that build a reflectarray can be shaped to bring about some flexibility in the way that antenna operates such as multi band/polarization operation. The printed nature of these elements allow integration of active elements that can further enhance the functionality of the reflectarray. This allows for capabilities such as power amplification, adaptive beam shaping, and beam switching. This resource presents readers with design guidelines along with an ample amount of material on different types of reflectarrays and methods of analysis. This book begins with introductory material on reflectarray antennas and progresses to the presentation of state-of-the-art research in the field. A direct comparison with conventional reflector antennas is provided, focusing on conventional efficiency figures of reflectors. Moreover, this book offers remarks on the future direction of reflectarray research and also potential applications of the technology in face of the emergence of new fabrication techniques to accommodate both passive and active elements.

Describes the configuration and principles of a reflectarray antenna, its advantages over other antennas, the history of its development, analysis techniques, practical design procedures, bandwidth issues and wideband techniques, as well as applications and recent developments. Both authors are well respected practitioners who have build these antennas and developed them for space flight.

Reflectarray (RA) antennas are introduced as an alternative to the conventional parabolic reflectors and antenna arrays. The RA provides the advantages of both reflectors and arrays. The narrow bandwidth is one of the distinct disadvantages of RA. The RA bandwidth is primarily limited by two factors, the element bandwidth, and the spatial phase delay. As the RA size is fixed with a proper focal distance, the second factor is hard to be used in the RA bandwidth optimization. It is impossible to design a broadband RA using narrowband elements, so wideband elements are developed in a unit cell of a periodic structure to further provide wider overall antenna bandwidth. In the literature review, 10-15 % RA bandwidth has been observed, which is mainly because of the used narrowband elements.Several RA antennas operating in the Ka-Band are designed and fabricated to learn an understanding of the RA with wideband characteristics. New wideband elements for linear polarization (LP) and circular polarization (CP) are utilized. A bandwidth of 22 % in LP-RA antennas is achieved using the proposed wideband elements. Over 50 % gain, and 50 % axial ratio bandwidth, and 57-62 % maximum aperture efficiency are experimentally measured for the CP. The effect of the edge diffraction on the phase correction is also investigated. The initial study showed little effect, but the considered RA size is small to highlight this effect. The matching of the feed is deteriorated when placed in front of the reflector. Therefore, few methods are implemented to improve the antenna reflection coefficients. The experimental results show possible improvements.The proposed work is categorized into three Parts. Part A provides a comprehensive study of the wideband element designs for both LP- and CP-RA. Part B utilizes the wideband elements developed in Part A, in the RA environment and introduces the performance of the antenna. In part C, textile-reflectarray (TRA) is proposed using conductive thread and shielded fabric, which is the first to be considered as a new trend in the field of RA. The element analysis and measurements show promising results. However, when implemented in the RA, the shielded fabric does not perform as expected. This problem is resolved by introducing a dual-sided embroidered reflectarray antenna where a flexible frequency selective surface (FSS) embroidered at the textile material using a conductive thread is used at the back side of the radiating elements replacing the ground plane. The measured results of the first ever built flexible, portable textile-RA show good antenna performance. An FSS based flexible portable and rollable circularly polarized TRA design is also presented using the wideband cross Bowtie elements. The radiating elements are embroidered using conductive thread.The initial results exhibit good performance of the proposed CP TRA antenna. For RA with small f/D, the spatial delay problem is the main reason for limiting the bandwidth even with wideband RA elements. This issue is solved by introducing a new split aperture into panels that reduce the difference in the path length between the center and those away towards the RA edge. This method shows a significant improvement in the RA bandwidth.

In recent years, transmitarray antennas have attracted growing interest with many antenna researchers. Transmitarrays combines both optical and antenna array theory, leading to a low profile design with high gain, high radiation efficiency, and versatile radiation performance for many wireless communication systems. In this book, comprehensive analysis, new methodologies, and novel designs of transmitarray antennas are presented. Detailed analysis for the design of planar space-fed array antennas is presented. The basics of aperture field distribution and the analysis of the array elements are described. The radiation performances (directivity and gain) are discussed using array theory approach, and the impacts of element phase errors are demonstrated. The performance of transmitarray design using multilayer frequency selective surfaces (M-FSS) approach is carefully studied, and the transmission phase limit which are generally independent from the selection of a specific element shape is revealed. The maximum transmission phase range is determined based on the number of layers, substrate permittivity, and the separations between layers. In order to reduce the transmitarray design complexity and cost, three different methods have been investigated. As a result, one design is performed using quad-layer cross-slot elements with no dielectric material and another using triple-layer spiral dipole elements. Both designs were fabricated and tested at X-Band for deep space communications. Furthermore, the radiation pattern characteristics were studied under different feed polarization conditions and oblique angles of incident field from the feed. New design methodologies are proposed to improve the bandwidth of transmitarray antennas through the control of the transmission phase range of the elements. These design techniques are validated through the fabrication and testing of two quad-layer transmitarray antennas at Ku-band. A single-feed quad-beam transmitarray antenna with 50 degrees elevation separation between the beams is investigated, designed, fabricated, and tested at Ku-band. In summary, various challenges in the analysis and design of transmitarray antennas are addressed in this book. New methodologies to improve the bandwidth of transmitarray antennas have been demonstrated. Several prototypes have been fabricated and tested, demonstrating the desirable features and potential new applications of transmitarray antennas.

Reflectarray antennas combine the numerous advantages of printed antenna arrays and reflector antennas and create a hybrid high-gain antenna with a low-profile, low-mass, and diversified radiation performance. Reflectarrays are now emerging as the new generation of high-gain antennas for long-distance communications. In this dissertation, some advanced concepts demonstrating novel features of reflectarray antennas are presented. * First, various approaches for radiation analysis of reflectarray antennas are described and implemented. Numerical results are then presented for a variety of systems and the advantages, limitations, and accuracy of these approaches are discussed and compared with each other. * A broadband technique by using sub-wavelength elements is proposed and prototypes are fabricated and tested. This technique enables the reflectarray to achieve a significant bandwidth improvement with no additional cost. * Infrared reflectarrays antennas are studied for possible applications in concentrating solar power systems. Material losses, an important design issue at infrared frequencies, are investigated and reflectarrays consisted of dielectric resonant elements are proposed with low-loss features at infrared. * Multi-beam reflectarray antennas are studied and it is demonstrated that by optimizing the phase of the elements, a desirable multi-beam performance can be achieved using a single-feed. Local and global phase-only optimization techniques have been implemented. Two Ka-band quad-beam prototypes with symmetric and asymmetric beams have been fabricated and tested. * Different approaches for beam-scanning with reflectarray antennas are also reviewed and it is shown that for moderately wide angle beam-scanning, utilizing a feed displacement technique is more suitable than an aperture phase tuning approach. A feed displacement beam-scanning design with novel aperture phase distribution is proposed for the reflectarray antenna, and is further optimized to improve the performance. A high-gain Ka-band prototype achieving 60 degrees scan range with side-lobe levels below 15 dB is demonstrated. * The feasibility of designing reflectarray antennas on conformal surfaces is also studied numerically. A generalized analysis approach is presented and the radiation performance of reflectarray antennas on singly-curved conformal cylindrical platforms are studied and compared with their planar counterpart. It is revealed that conformal reflectarray antennas are a suitable choice for a high-gain antenna where curved platforms are required. In summary, different challenges in reflectarray analysis and design are addressed in this dissertation. On the element design challenges, bandwidth improvement and infrared operation of reflectarray antennas have been studied. On the system level challenges, multi-beam designs, beam-scanning performance, and conformal platforms have been investigated. Several prototypes have been fabricated and tested, demonstrating the novel features and potential applications of reflectarray antennas.

With the growing of wireless technology, the need for lower-profile, electronically reconfigurable, highly-directive beam-steering antennas is increasing. This thesis proposes a simple low loss, low cost electronic beam-steering antenna architecture by combining a variety of concepts including the single bit phase shifter, sub-wavelength element spacing and delta-sigma modulation. The starting point in the design of reflectarray antennas is the derivation of the so-called S-curve, which maps changes in unit cell design parameters to the phase of the scattered field from the cell. Both numerical and analytical techniques for analyzing linear-polarized fixed and reconfigurable reflectarray unit cell with lumped element has been developed. A 16 Ă 16 element reflectarray prototype operating at 5.5 GHz is presented the low loss performance and a beam-steering range of -20 to +20 degrees with a single bit phase shifter.