Reconfigurable Reflectarrays and Array Lenses for Dynamic Antenna Beam Control: A Review

Advances in reflectarrays and array lenses with electronic beam-forming capabilities are enabling a host of new possibilities for these high-performance, low-cost antenna architectures. This paper reviews enabling technologies and topologies of reconfigurable reflectarray and array lens designs, and surveys a range of experimental implementations and achievements that have been made in this area in recent years. The paper describes the fundamental design approaches employed in realizing reconfigurable designs, and explores advanced capabilities of these nascent architectures, such as multi-band operation, polarization manipulation, frequency agility, and amplification. Finally, the paper concludes by discussing future challenges and possibilities for these antennas.Comment: 16 pages, 12 figure

Dual-Layer Single-Varactor Driven Reflectarray Cell for Broad-Band Beam-Steering and Frequency Tunable Applications

A dual-layer active reflectarray configuration is proposed for broad-band beam-steering and/or frequency-tunable applications. A unit cell composed by two stacked fixed-size rectangular patches, properly loaded with a single varactor diode, is designed to realize the dynamic phase tuning mechanism. The proposed approach offers wider bandwidths, with respect to the existing varactor-based reflectarray cells, and quite good frequency reconfigurability features, as demanded by several radar or satellite communication applications. An X-band reflectarray cell is fabricated and tested, to prove the effectiveness of the proposed approach, achieving a 318° phase agility within a measured frequency range of about 14.6% with respect to the central design frequency (i.e., 11 GHz). Wideband beam-steering reflectarray designs are demonstrated, showing 1-dB gain bandwidths equal to 9-10%

Broadband Approaches And Beam-Scanning Techniques For Reflectarray Antenna

Reflectarray antennas combine the numerous advantages of reflector antennas and phased array antennas and create a hybrid high-gain antenna with a low-profile, low-mass, easy-fabrication, and diversified radiation performance. However, it still has some inherent drawbacks, such as limited bandwidth and scanning range, which are targeted in this dissertation. At first, the array theory approach for radiation analysis of reflectarray antennas is described and implemented. Numerical results are then presented and compared with reference results to confirm its reliability. As the most critical influential factor to the reflectarray bandwidth, the element bandwidth was studied at first, and the effects of element shape and substrate thickness were investigated. Then, a comprehensive study was performed to investigate the bandwidth performance of reflectarrays on the system level. The effect of aperture size, element bandwidth and phase synthesis method was discussed in sequence. Particularly, a novel phase synthesis approach was proposed, which enables reflectarray to achieve a significant bandwidth improvement even with elements of narrow bandwidth. Prototypes are fabricated and tested to validate the idea. Since the reflectarray antenna is a hybrid product of reflector and phased array antennas, its main beam could be steered by either rotating its feed or reconfiguring its element phases. The former way was explored at first. An improved phase design was proposed for reflectarrays mimicing parabolic-cylindrical reflectors to expand its scanning range. The published achievements of reconfigurable reflectarrays design are revieand it is found that currently efficiency is a big problem. A 1-bit 10ã—10 reconfigurable reflectarray using pin diode was designed, fabricated and measured to explore the energy loss, and experimental results shothat 14% efficiency could be reached. In summary, some improved designs regarding bandwidth and scanning performance for reflectarrays are proposed in this dissertation. Various factors affecting reflectarray bandwidth are investigated, which shall provide some guidelines regarding bandwidth improvement. On the other hand, two designs are presented to explore the beam scanning characteristic of reflectarray antenna, by mechanical and electrical ways respectively. Several prototypes have been fabricated and measured, demonstrating the novel features and potential applications of reflectarray antennas

Recon gurable Antennas Based on Varactor-Loaded Stubs

The term “reconfigurable” is typically used for devices which exhibit some flexibility of functionalities and agility in their operation characteristics, with the aim of achieving high performance in various conditions. In antenna technology, the reconfiguration can be fulfilled through several techniques that provide an ability to modify the electrical current on the antenna’s structure, primarily to accomplish a physically realised new response. The main key to the reconfigurable antenna application is their potential to avoid the use of multiple antennas for multi-functionality, thus facilitating miniaturisation of the antenna system configuration. In this context, several novel reconfigurable antennas with a wide performance range are proposed in this thesis. Varactor-loaded stubs are used as tuning mechanism for these microwave antenna designs with improved performance throughout this thesis. Two types of electromagnetic structures are studied in this work, namely reconfigurable antennas and reconfigurable periodic structures, with these two main topics building the two main major parts of this thesis. In its first main part, the thesis proposes reconfigurable antenna designs with combined frequency and pattern reconfigurable characteristics. The main focus is first on the manipulation of near-resonant current distributions in a two-element array antenna as well as the optimisation of their feeding through T-junction power dividers. Each element has a controllable active component that allows the antenna to be tuned to different operating frequencies, while the concurrent adaption of the two elements is the basis of continuous beam scanning characteristics. Next, the thesis examines the exploitation of a single-element antenna structure based on the same operation principle. An optimisation procedure including a study of relevant design parameters is also presented. The core contribution for the two-element array and the single-element antenna is that they combine frequency-reconfigurability with effective beam scanning. The main difference between the two designs however is that they scan in the H-plane and the E-plane, respectively. In the second main part, the thesis focuses on a reconfigurable reflectarray antenna design. Potential applications of this advanced antenna design include the development of high gain antennas with various controllable reflection beam directions throughout a wide range of operation frequencies. The proposed reflectarray antenna unit cell is firstly proposed, together with an opimisation of the antenna characteristics in terms of reflection loss and phase range performance. It is further shown that the proposed antenna provides an excellent performance compared to the state-of-the-art. Performance measures include a near full phase tuning range of about 300 to 320 with a reflection loss of magnitude better than 3 dB within a fractional frequency range of operation of 18%. In contrast, most reflectarray antenna designs in the literature provide a limited phase range at a fixed operating frequency or within a narrower frequency tuning range. Experimental validation is provided with a 12-element linear reflectarray tested in twodimensional settings, for which the experimental challenges are also discussed in detail. The capability of reflected beam scanning is verified and successfully demonstrated.Thesis (Ph.D.) -- University of Adelaide, School of Electrical & Electronic Engineering, 201

Bilgi toplumu teknolojileri için anten sistemleri ve algılayıcılar

TÜBİTAK EEEAG01.10.2010Bu proje kapsamında, özellikle milimetre-dalga frekanslarında çalışan yeniden şekillendirilebilir anten, elektronik taramalı dizi anten ve yansıtıcı dizi anten tasarımı, üretimi ve ölçümleri yapılmıştır. Yeniden şekillendirilebilirlik özelliği için farklı teknolojiler kullanılmıştır. Huzmesi yönlendirilebilen sur biçimli mikroşerit yürüyen dalga anten dizisi X-bant uygulamalarında kullanılmak üzere tasarlamış, üretilmiş ve ölçülmüştür. Antenin ana huzmesinin istenilen yöne elektronik olarak döndürülebilmesini sağlayabilmek için mikroşerit hat üzerinde gerekli faz değişimini sağlayacak varaktör diyotlar kullanılmıştır. Yapılan EM benzetim ve ölçümler sonucu sur biçimli anten dizisinde, ana huzmenin diyot kontrolü ile tasarlandığı gibi 10 lik bir açı taraması yapabildiği gösterilmiştir. Bu kavram kanıtlaması şeklinde bir çalışmadır; huzmenin daha büyük açı aralığında tarama yapması için tasarımda yapılması gereken değişiklikler belirtilmiştir. MM-Dalga sabit genişlikli ve doğrusal sönümlenen yarık antenler tasarlanıp, üretilmiş ve antenin şeklinin, optik uyarımla bu iki yapı arasında değiştirilmesinin sağlanması durumunda ışıma örüntüsünün değiştirilebileceği gösterilmiştir. Proje kapsamında gerçekleştirilen bir diğer çalışmada da K ve Ka bantlarında bağımsız çalışabilen, RF MEMS anahtarlarla huzmesi elektronik olarak döndürülebilen dairesel polarizasyonlu yansıtıcı dizi anten tasarlanmış, üretilmiş ve ölçülmüştür. Çift frekanslı (24.4 GHz ve 35.5 GHz) dizi iç içe geçmiş farklı boyutlarda iki ayrık-halka dizisi şeklinde tasarlanmıştır. Huzme döndürme amacıyla her bir ayrık halkanın açısal konumunu RF MEMS anahtarlarla ayarlayarak, dairesel polarizasyonlu dalgaların fazları kontrol edilmektedir. Anten ODTÜ MEMS merkezinde geliştirilen yüzey mikro-işleme süreciyle üretilmiştir. Işıma örüntüleri ölçülmüş ve benzetim sonuçlarıyla karşılaştırılmıştır. Ölçümlerle, ana huzmenin, tasarlandığı gibi, Ka bandında 35°‟ye, K bandında 24°‟ye döndürülebildiği gösterilmiştir. Proje çalışmalarından sur biçimli mikroşerit anten dizisiyle ilgili hazırlanan makale Microwave and Optical Technology Letters adlı dergide yayınlanmak üzere kabul edilmiştir. Yansıtıcı dizi antenle ilgili makale de hazırlık sürecindedir. Saygın konferanslarda yedi bildiri sunulmuştur. Ayrıca, proje kapsamında üç yüksek lisans tez çalışması tamamlanmıştır.In this project, reconfigurable antenna, beam steering array and reflectarray have been designed, produced and measured, especially in mm-wave frequencies. To provide reconfigurability, different technologies have been considered. X-band electronically scanning meanderline microstrip traveling wave antenna array has been designed, produced and measured. To rotate the antenna beam to the desired direction, microstrip meander line has been loaded by varactor diodes that provide required phase shift values. EM simulations and rdiation pattern measurements of the meanderline antenna have demonstrated that the antenna has the capability to scan 10 with the control of varactors as designed. This is a proof-of-concept type study; alternative configurations to increase the scan range have also been discussed. MM-wave tapered slot antennas with a constant width and linear taper have been designed, produced and measured. It has been demonstrated that if the shape of the tapered slot antenna can be changed between constant width and linear taper structures by means of optical excitation, radiation pattern reconfigurability can be obtained. In another study accomplished in this project, electronically scanning circularly polarized reflectarray working independently in K and Ka bands has been designed, produced and measured. Dual band (24.4 GHz and 35.5 GHz) reflectarray has been designed as an interlaced array of split rings of two different sizes. In order to steer the beam, the phase of the incident circularly polarized wave is controlled by RF MEMS switches that modify the angular orientation of split-rings individually. The antenna has fabricated by using surface micromachining process developed in METU MEMS Center. Radiation patterns of the antenna are measured and compared with the simulations. It has been shown that the reflectarray is capable of beam switching to 35° in Ka band, 24° in K band as required. One journal paper on meanderline antenna has been accepted to be published in Microwave and Optical Technology Letters. Preparation of manuscript on reflectarray is under progress. Seven conference papers have been presented in well known Conferences. Furthermore, three Master Thesis studies have been accomplished during the project

Electromagnetic Modeling of Reflectarrays using Scale Changing

De nos jours, les antennes sont de plus en plus complexes en raison notamment de la nécessité de réaliser une reconfigurabilité en fréquence et/ou en diagramme. Les réseaux réflecteurs et les surfaces sélectives en fréquence sont des candidats particulièrement intéressants pour couvrir les besoins actuels. Cependant, en raison de leur grande taille et de la complexité géométrique croissante de leurs cellules élémentaires, l‘analyse électromagnétique complète de ces structures rayonnantes nécessite énormément de ressources informatiques (mémoire) et exige des temps de calcul prohibitifs, notamment lorsque des éléments de commande tels que des MEMS-RF sont intégrés au sein des cellules. Les techniques numériques classiques basées sur un maillage (spatial ou spectral) systématique ne parviennent pas à simuler de manière efficace de telles structures multi-échelles et nécessitent souvent des ressources informatiques difficiles d’accès pour le concepteur d'antennes. Une technique originale baptisée « Scale Changing Technique (SCT) » tente de résoudre ce problème en segmentant le réseau en de multiples domaines imbriqués les uns dans les autres et présentant divers niveaux d'échelle. Le multi-pôle par changement d’échelle, appelé « Scale Changing Network (SCN) », modélise le couplage électromagnétique entre deux niveaux d’échelle successifs. Ce multi-pôle peut être calculé en résolvant les équations de Maxwell à partir d’une Formulation par Equations Intégrales. La mise en cascade des multi-pôles par changement d’échelle permet alors le calcul de la matrice impédance (ou admittance) de surface du réseau complet. Cette matrice peut à son tour être utilisée pour simuler la diffusion électromagnétique d’une onde incidente par le réseau. Le calcul des différents multi-pôles par changement d’échelle peut être effectué séparément de sorte que le temps de simulation du réseau complet peut être considérablement réduit en parallélisant le calcul. Par ailleurs, la modification de la géométrie de la structure à une échelle donnée, lors de la phase de conception, nécessite seulement le calcul de deux multi-pôles par changement d’échelle et ne requiert pas une nouvelle simulation de toute la structure. Cette caractéristique fait de la SCT un outil de conception modulaire. Dans le cadre de cette thèse, la SCT a permis de tenir compte de la taille finie des réseaux et de modéliser efficacement les couplages électromagnétiques entre les cellules élémentaires. Des réseaux réflecteurs uniformes et non uniformes ont été simulés par la SCT et les performances numériques de la méthode ont été analysées. ABSTRACT : Future antenna architectures especially for space applications are becoming more and more complex due to the need of reconfigurability. This reconfigurability is needed in terms of frequency, reliability, radiation pattern and power consumption. In this context, reflectarrays and frequency selective surfaces (FSSs) are particularly the hottest domains of RF design. The accurate analysis of electromagnetic (EM) scattering from such type of complex finite-sized reflectarray antenna structures is of great practical interest. However due to their large electrical size and complex cellular patterns specially when tuning elements such as RF-MEMS are also integrated within the array elements, conventional full-wave EM analysis of such multiscale structures either fail or require enormous amount of computational resources to resolve prohibitively large number of unknowns. Moreover the characterization of large structures would normally require a second step for optimization and fine-tuning of several design parameters, as the initial design procedure assumes several approximations. Therefore a full-wave analysis of the initial design of complete structure is necessary prior to fabrication to ensure that the performance conforms to the design requirements. A modular analysis technique which is capable of incorporating geometrical changes at individual cell-level without the need to rerun the entire simulation is extremely desirable at this stage. An indigenous technique called Scale Changing Technique (SCT) addresses this problem by partitioning the cellular reflectarray geometry in numerous nested domains and subdomains defined at different scale-levels in the array plane. Multi-modal networks, called Scale Changing Networks (SCNs), are then computed to model the electromagnetic interactions between any two successive partitions by method of moments (MoM) based integral equation approach. The cascade of these networks allows the computation of the equivalent surface impedance matrix of the complete array which in turn is utilized to compute far-field radiation patterns. Full-wave analysis of both passive and active (electronically tunable by RF-MEMS) reflectarrays has successfully been performed by the SCT while utilizing very small amount of computational resources as compared to conventional full wave methods. Moreover, to speed up the SCT modeling of the reflectarrays, equivalent electrical circuit models have been extracted and applied for individual design and optimization of the reflectarray phase shifter elements

時間変調リフレクトアレーの研究

Tohoku University博士（工学）thesi

Antenna Designs for 5G/IoT and Space Applications

This book is intended to shed some light on recent advances in antenna design for these new emerging applications and identify further research areas in this exciting field of communications technologies. Considering the specificity of the operational environment, e.g., huge distance, moving support (satellite), huge temperature drift, small dimension with respect to the distance, etc, antennas, are the fundamental device allowing to maintain a constant interoperability between ground station and satellite, or different satellites. High gain, stable (in temperature, and time) performances, long lifecycle are some of the requirements that necessitates special attention with respect to standard designs. The chapters of this book discuss various aspects of the above-mentioned list presenting the view of the authors. Some of the contributors are working strictly in the field (space), so they have a very targeted view on the subjects, while others with a more academic background, proposes futuristic solutions. We hope that interested reader, will find a fertile source of information, that combined with their interest/background will allow efficiently exploiting the combination of these two perspectives

Design and analysis of wideband passive microwave devices using planar structures

A selected volume of work consisting of 84 published journal papers is presented to demonstrate the contributions made by the author in the last seven years of his work at the University of Queensland in the area of Microwave Engineering. The over-arching theme in the author’s works included in this volume is the engineering of novel passive microwave devices that are key components in the building of any microwave system. The author’s contribution covers innovative designs, design methods and analyses for the following key devices and associated systems: Wideband antennas and associated systems Band-notched and multiband antennas Directional couplers and associated systems Power dividers and associated systems Microwave filters Phase shifters Much of the motivation for the work arose from the desire to contribute to the engineering o