- C. Balanis (bio), Arizona State University -USA, "EM Band-Gap High Impedance Surfaces for Conformal Low-Profile Antennas and RCS Reduction" (abstract)
- J. T. Bernhard (bio), University of Illinois - USA, "Challenges for Characteristic Modes in Antenna Design" (abstract)
- J. R. Mosig (bio), École Polytechnique Fédérale de Lausanne - Switzerland, "New antenna designs for Ka-band and higher frequencies using 3D-printing technologies" (abstract)
- J. Sahalos (bio), University of Nicosia - Cyprus & Aristotle University of Thessaloniki - Greece, "The Orthogonal Methods for Antenna Arrays Beam-forming" (abstract)
- N. K. Uzunoglu (bio), National Technical University of Athens - Greece, "The Balance Between Computation and Intuition in Antenna Design" (abstract)
The final schedule will be announced.
EM Band-Gap High Impedance Surfaces for Conformal Low-Profile Antennas and RCS Reduction
Abstract: High impedance surfaces (HISs) have emerged as one of the advances in the modern antenna design. They have been extensively used in low-profile antenna designs because of their in-phase reflection characteristics in certain frequency band(s); hence the name EM Band-Gap (EBG) structures. HISs can also be utilized for antenna miniaturization and bandwidth enhancement, and they have also been used as attractive ground planes and checkerboard surface variations of them as radar targets for RCS reduction.
While planar rectilinear HISs have been used as ground planes for both linear and curvilinear elements (loops and spirals), the focus on planar circularly symmetric HISs has been minimal. In this presentation we will concentrate on circularly symmetric HISs, especially in conjunction with curvilinear elements, such as loops and spirals. It will be shown that the unique phase profile of the circular HISs formed by the excitation of the incident waves from curvilinear radiating elements, such a loops or spirals, provide more symmetric amplitude radiation patterns and a constructive interference between the direct and reflected waves which increases the gain by nearly an additional three dB, compared to ideal PMC ground planes, for a total gain of about 8.5-9 dB. Both of these unique characteristics are confirmed by comparisons between simulations and measurements, and with excellent agreement.
Two conventional methods to reduce the RCS of a structure is to changes its shape so it redirects the scattered fields away from the observer or to apply radar absorbing material (RAM) to absorb some of the power of the incident waves. Both of these designs possess strengths and drawbacks. A more recent alternate design to achieve the same objective, reduction of the RCS, is to coat the radar target with checkerboard EBG designs of patches of different configurations. The incident waves on these checkerboard patches induce current densities whose amplitude and phase, especially the phase, are different as a function of frequency between the two sets of adjacent patch designs. These appealing induced surface current densities act as antenna array elements with difference amplitude and phase excitation, and they, especially the phase, can be taken advantage to form constructive and destructive interference scattering patterns, to reduce the intensity of the scattered fields toward the observer; thus reducing the RCS. EBG checkerboard structures, with PEC and ideal PMC patches, possess 180o phase difference between the scattered fields from adjacent checkerboard patches which result in cancellation of the scattered fields. By utilizing two different EBG set of patches, instead of PEC and PMC, can form constructive and destructive interference patterns as a function of frequency. While symmetric square-shaped checkerboard surfaces produce four redirected lobes of the bistatic scattered fields, a hexagonal design creates six redirected lobes, which further reduce the peak intensity of the redirected bistatic lobes. Also the bandwidth of such checkerboard surfaces can be enhanced by combining two different EBG set of patches, each with different shape patches and resonant frequencies, on the same ground plane. It will be shown that the 10-dB RCS reduction bandwidth, compared to a PEC plate, can be extended from nearly 40% to nearly 63%, and even greater, for both square and hexagonal ground plane shapes. Such checkerboard surfaces have been designed, simulated, and measured with excellent agreement between the two sets of data.
Constantine A. Balanis (S'62 - M'68 - SM'74 - F'86 – LF'04) received the BSEE degree from Virginia Tech, Blacksburg, VA, in 1964, the MEE degree from the University of Virginia, Charlottesville, VA, in 1966, and the Ph.D. degree in Electrical Engineering from Ohio State University, Columbus, OH, in l969. From 1964-1970 he was with NASA Langley Research Center, Hampton VA, and from 1970-1983 he was with the Department of Electrical Engineering, West Virginia University, Morgantown, WV. Since 1983 he has been with the School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, where he is Regents' Professor. His research interests are in computational electromagnetics, flexible antennas and high impedance surfaces, smart antennas, and multipath propagation. He received in 2004 a Honorary Doctorate from the Aristotle University of Thessaloniki, the 2014 James R. James, Lifetime Achievement Award, LAPC, Loughborough, UK, the 2012 Distinguished Achievement Award of the IEEE Antennas and Propagation Society, the 2012 Distinguished Achievement Alumnus Award (College of Engineering, The Ohio State University), the 2005 Chen-To Tai Distinguished Educator Award of the IEEE Antennas and Propagation Society, the 2000 IEEE Millennium Award, the 1996 Graduate Mentor Award of Arizona State University, the 1992 Special Professionalism Award of the IEEE Phoenix Section, the 1989 Individual Achievement Award of the IEEE Region 6, and the 1987-1988 Graduate Teaching Excellence Award, School of Engineering, Arizona State University.
Dr. Balanis is a Life Fellow of the IEEE. He has served as Associate Editor of the IEEE Transactions on Antennas and Propagation (1974-1977) and the IEEE Transactions on Geoscience and Remote Sensing (1981-1984); as Editor of the Newsletter for the IEEE Geoscience and Remote Sensing Society (1982-1983); as Second Vice-President (1984) and member of the Administrative Committee (1984-85) of the IEEE Geoscience and Remote Sensing Society; and Distinguished Lecturer (2003-2005), Chair of the Distinguished Lecturer Program (1988-1991), member of the AdCom (1992-95, 1997-1999) and Chair of the Awards and Fellows Committee (2009-2011) all of the IEEE Antennas and Propagation Society. He is the author of Antenna Theory: Analysis and Design (Wiley, 2016, 2005, 1997, 1982), Advanced Engineering Electromagnetics (Wiley, 2012, 1989) and Introduction to Smart Antennas (Morgan and Claypool, 2007), and editor of Modern Antenna Handbook (Wiley, 2008) and for the Morgan & Claypool Publishers, series on Antennas and Propagation series, and series on Computational Electromagnetics.
Abstract: The art of antenna design has often been described as “black magic.” Of course, we practitioners know that this magic is really a combination of experience and insight based on strong theoretical foundations. The explosion of interest and activity in characteristic modes and indeed, modal analysis in general, reflects the desire for more insight as our design problems become more and more complicated in terms of operating frequencies and bandwidths, required patterns, size, scale, materials, and platforms. While our community has made great strides in using characteristic mode analysis to provide crucial operational perspective, applying characteristic mode theory to these kinds of problems to arrive at useful design conclusions becomes increasingly complex.
This presentation will provide a brief overview of the applications of characteristic mode theory in design, and then outline and discuss the current challenges that we face as designers to bring this very powerful tool to bear on new classes of problems.
Jennifer T. Bernhard earned the B.S.E.E. degree from Cornell University in 1988 and the M.S. and Ph.D. degrees in Electrical Engineering from Duke University in 1990 and 1994, respectively. From 1995-1999, Prof. Bernhard was an Assistant Professor in the ECE Department at the University of New Hampshire, where she held the Class of 1994 Professorship. Prof. Bernhard has been a faculty member in the Electromagnetics Laboratory in the Department of Electrical and Computer Engineering at the University of Illinois since 1999. She was named the Donald Biggar Willett Professor in Engineering in 2016.
Her research group focuses on the development and analysis of multifunctional reconfigurable antennas and their system-level benefits as well as the development of antenna synthesis and packaging techniques for electrically small, planar, and integrated antennas for wireless sensor and communication systems. She and her students hold five patents in these areas. In addition to the NSF CAREER Award, the IEEE Antennas and Propagation Society H. A. Wheeler Prize Paper Award and other research recognitions, she has been honored with a number of teaching and advising awards. She has authored over 250 publications and has advised over 60 graduate students. .
She is a Fellow of the IEEE, and in 2008, she served as the President of the IEEE Antennas and Propagation Society. Since 2012, she has also served as the Associate Dean for Research in the College of Engineering at Illinois. She is a member of the IEEE Board of Directors in 2017-2018 as Division IV Director and also sits on the ASEE Engineering Research Council Executive Board
Abstract: In July 2016, the US Federal Communications Commission confirmed the choice of several Ka-band frequencies as the preferred spectrum to support the implementation of the spectrum for the fifth generation of mobile systems and wireless broadband services (5G). This is to be added to the nowadays well established use of Ka-band frequencies for bidirectional (Tx/Rx) satellite communications. As a result of this double trend, the interest for developing new antenna designs, specifically suited to these frequency bands and with increased performances, is greatly enhanced.
In this paper, we consider two enabling technologies that can be used to develop new antennas types or to successfully scale to Ka-band and above designs that previously were only realizable at much lower frequencies. These technologies are, on one side, the recent extensions of the Surface Integrated Waveguide (SIW) technologies and, on the other hand, some varieties of Additive Manufacturing (AM) technologies (commonly known as 3D printing). In both cases, the aim is the same: to produce compact and inexpensive antennas that can work directly in Ka-band frequencies or that are easily scalable to these frequencies and above. The antennas should also offer the possibility of easy integration in complete antenna subsystems that would use the same or related technologies. Finally, for satellite applications, dual-band capabilities are essential to cover the transmitting and receiving operation modes, and dual polarization capabilities are unavoidable to generate the circularly polarized waves required in space applications.
Recently an extended Surface Integrated Waveguide (eSIW) technology has been used to create a new antenna, the H-planar horn, which despite its thinness can be excited with two orthogonal modes and thus being used to create a dual-polarized antenna subsystem including an integrated orthomode transducer (OMT) while requiring only a two-layer substrate. This type of integrated planar horn, originally developed in Ku-band, has been scaled to Ka-band and a new technology, the gap-SIW, has been used to enhance simultaneously its gain and bandwidth. The second enabling technology under discussion is Additive Manufacturing (AM), which allows to realize high performance low-cost antennas for Ka-band applications. At these frequencies, designs resulting in split-block elements that must be mechanically assembled, start showing their limitations. AM emerges in this context as a change of paradigm, allowing monolithic fabrication and design freedom, which result in substantial improvements in terms of compactness, mass, simplicity, cost and production time. The AM version described here is a stereolithographic (SLA) process followed by metal coating, which is very convenient for designs including internal shapes that are inaccessible to conventional machining tools. To conclude this presentation, several different antennas for Ka-band satellite communications, realized with an AM-SLA proprietary technology, will be shown and its performances discussed in detail.
*The presenter would like to thank the paper's co-authors M. Garcia-Vigueras, J. S. Silva, T. Debogovic and M. Esquius
Juan R. Mosig was born in Cadiz, Spain. He received the Electrical Engineer degree from the Universidad Politecnica de Madrid, Madrid, Spain, in 1973, and the Ph.D. degree from the Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland, in 1983. Since 1991, he has been a Professor in the Laboratory of Electromagnetics and Acoustics (LEMA) at EPFL and its Director since 1999. He has held scientific appointments with the Rochester Institute of Technology, Rochester, NY, USA; the Syracuse University, Syracuse, NY, USA; the University of Colorado at Boulder, USA; University of Rennes, Rennes, France; University of Nice, Nice, France and the Technical University of Denmark, Lyngby, Danemark.
Dr. Mosig has been a member of the Swiss Federal Commission for Space Applications, the Chairman of the EPFL Space Center, the Director of the Electrical Engineering Section at EPFL and a ViceDean of the Humanities and Social Sciences College at EPFL. He has authored four chapters in books on planar antennas and circuits and more than 700 publications, including more than two hundred papers in peer-reviewed top international journals. He is the recipient of the 2015 IEEE APS Schelkunoff Award for the best Transactions AP paper of the year. His research interests include electromagnetic theory, numerical methods, and planar antennas. Dr. Mosig has been the Swiss Delegate for European COST Antenna Actions since the 1980's and the Chair for the two last completed Actions 284 and IC0603 ASSIST (2003–2011). He is now a member of the COST Senior Scientific Committee. He is a founding member and Chair of the European Association on Antennas and Propagation (EurAAP) and leads the Steering Committee organizing the EuCAP Conferences series. He will be the Conference Chair for EuCAP’2016 (Davos, Switzerland, April 10-15, 2016). He has been a member of the IEEE APS AdCom, first as Transnational Delegate and then as EurAAP representative. He is currently the Swiss Delegate in the URSI Commission B
Abstract: The theory and applications of the Orthogonal Methods (OM) with and under several constraints will be presented. The basic idea of the OMs is to transform the basis of the vector space of the radiated field of an antenna array to a corresponding orthogonal one. In the new basis the unknown characteristics of the antenna can be easily found. In the first part of the presentation the excitation of the array elements is derived. In the second part, instead of the excitation, the geometry synthesis by using the orthogonal perturbation method is applied. Several examples of linear, planar and conformal arrays for beam-forming of base stations as well as of modern satellite communications antennas will be presented.
John N. Sahalos received his B.Sc. degree, MS degree and Ph.D degree in Physics from the Aristotle University of Thessaloniki, (AUTH), Greece. He also received the Diploma (BCE+MCE) in Civil Engineering from the same University. In 1976, he was a Postdoctoral University Fellow at the ElectroScience Laboratory, the Ohio State University, Columbus, Ohio. From 1977 to 1986, he was a Professor in the ECE Department, University of Thrace, Greece, and Director of the Microwaves Laboratory. From 1986 to 2010, he has been a Professor at the School of Science, AUTH, where he was the director of the postgraduate studies in Electronic Physics and the director of the Radio-Communications Laboratory (RCL). Dr. Sahalos is a Professor at the ECE Department of the University of Nicosia, Cyprus since 2010. He was a visiting Professor at the ECE Departments, University of Colorado, Boulder and the Technical University of Madrid, Spain. He is the author of 5 books, of many book chapters and more than 450 articles published in the scientific literature. Dr. Sahalos is a Professional Engineer and a Consultant to industry. He was in the Board of Directors of the OTE, the largest Telecommunications Company in Southeast Europe. He also served, as a technical advisor in several national and international committees, as well as, in three Mobile Communications Companies. For more than 10 years he was the president of the Greek committees of URSI. He was the president of ICT in the National Committee of Research and Technology of Greece. Dr. Sahalos is a Life Fellow of the IEEE. He also is a member of the Greek Physical Society, an Honor Fellow of Radio-Electrology and a member of the Technical Chamber of Greece. Dr. Sahalos was the Vice-Chairman of the Research Committee of AUTH and in the Board of Directors of the University of Nicosia Research Foundation (UNRF). With his colleagues Prof. Sahalos designed several well known innovative products like the Electric Impedance Tomography, (EIT), the Microwave Landing System, (MLS), the ORAMA simulator and the SMS-K monitoring system.
Abstract: Antenna Engineering from the beginning of implementing ideas of J.C. Maxwell on radiating electromagnetic waves, being the first H. Hertz experiments, was based on the concept of dipole element. G. Marconi made use of this same idea in his pioneering work. The difficulty of computing real antenna structures and thus generating numerical results for real antennas was compensated in the development of antennas, by the use of intuitive ideas and experiments by using models. However, still the essential understanding of the principles of radiation phenomena in classical physics sense, proved to be the most important tool in the development of antennas. To give two examples: (a) the development of reflector antennas in 1940’s and (b) the frequency independent antennas in 1950’s.
Today the development of powerful computational tools gives the opportunity in modelling accurately relatively large antennas being in size many times of the wavelength. However, still the essential understanding of radiation – scattering mechanisms is of fundamental importance to design and development new antennas to satisfy the specifications stated by the user. This means the education of engineering students should cover both aspects, that is the deep understand (in Greek empedosi – in an embedded sense) radiation phenomena principles and also the ability to use advance electromagnetic computational tools. Several successful examples antenna designs by combing intuition and computation tools will be presented in the talk. Finally cases of pitfalls, of selecting candidate antenna structures, violating radiation principles, despite intuitively make sense as possible radiators will be presented to emphasize the importance of avoiding selections based on misconceptions.
Nikolaos K. Uzunoglu was born in Istanbul in 1951. He graduated as Electronic Engineer from the Istanbul Technical University in 1973. He obtained his Master in Science and Doctor of Philosophy degrees in Electrical Engineering Science at the University of Essex, United Kingdom in 1974 and 1976 respectively. He obtained his Doctor of Science Degree in 1981 at the National Technical University of Athens-Greece in the scientific field of Electro-optic Systems. He was elected as Associate Professor at the National Technical University of Athens (1984) and promoted to Professor in 1987. He was elected and served as a Dean of the School of Electrical and Computer Engineering (1988-94) and established the Research Institute of Communications and Computer Systems (1991-99).
Dr. Uzunoglu has been coordinator to a large number of Research Projects of European Commission (40) starting from 1984. In 2005 he was honored with the IEEE Fellow membership. The research fields he worked include: Electromagnetic Theory and its Applications in Telecommunications, Sensors, Biomedical Engineering and Remote Sensing. He has designed and developed numerous prototype systems based on novel concepts of Electromagnetism. His research work combines theory and experiment. He has published 250 papers in internationally recognized peer reviewed scientific journals and he authored 5 books. He has supervised 60 Ph. D students. He has been scientific coordinator in 20 European Projects related to Telecommunciations (Fiber Optics, Satellite and Terrestrial Communications) and Applied Electromagnetism. He is active in the research fields: antennas, microwave circuits and systems, digital communications and application of electromagnetic technology in biomedical engineering.