1999 Events:
November 18, 1999: "A Circuit-Fed, Tile-Approach Configuration for Millimeter Wave Spatial Power Combining " by Dr. Mark Gouker, MIT Lincoln Lab
Abstract: Spatial and quasi-optical power combining are promising techniques to efficiently combine the output power from a large number of solid state devices. In this technique the outputs of many solid state devices, i.e. diodes, transistors, or MMIC amplifiers, are combined in free space rather than in a lossy waveguiding structure as is done in conventional moderate output power solid-state amplifiers.
This talk describes a circuit-fed, tile-approach configuration for spatial power combining. The basic circuit topology resembles tile-approach, active phased arrays; however, the details of the implementation are tailored for the spatial power combining problem. The basic building block in the array is a 16 element "tile" subarray composed from 16 MMIC amplifiers and 16 microstrip patch antennas. Each of these subarrays is a multi-layer multichip module with the MMIC amplifiers on one layer and the patch antennas on a second. The performance of a prototype array is described. The array operates between 43.5 GHz and 45.5 GHz, contains 256 elements, and produces 6 watts of transmitted power.
Bio: Mark Gouker attended Emory University in Atlanta where in 1983 he received the BS degree in Physics. In 1985 he receive the MS degree in Electrical Engineering from the Georgia Institute of Technology. From 1985 to 1987 he was a research engineer in the Millimeter Wave Technology Division of the Georgia Tech Research Institute. In 1988 he returned to school at Georgia Tech and received the Ph.D. degree in Electrical Engineering in 1991. The subject of his dissertation was millimeter wave integrated circuit dipole antennas with integrated Fresnel zone plate reflectors. In 1991 he joined MIT Lincoln Laboratory where his work has concentrated on spatial power combining.
October 15, 1999: "'Smart' Antennas for Wireless Communications" by Dr. Richard Roy, ArrayComm, Inc.
Abstract: Space is truly one of the "final frontiers" when it comes to next generation wireless communication systems. Large-scale penetration of such systems into our daily lives will require the significant reductions in cost and increases in capacity that only the spatial dimension can hope to offer. That this is certainly the case is attested to by the significant number of companies that have been recently formed to bring products based on such concepts to the wireless marketplace as well as recent announcements from major Manufacturers. The approachs range from switched-beam to fully-adaptive, with the benefits provided by the various approaches differing accordingly.
Exploitation of the spatial dimension in some form or another has been going on since wireless communications came into being. The basic concept cellular systems rely on is that RF only "goes so far", a concept that has been taken full advantage of in broadcast TV and radio since their inception. This is clearly the simplest form of more efficient use (or reuse if you will) of the spatial dimension. As the center frequency of such systems increased along with the desire for mobility, the complexity of the RF environment increased as well, necessitating further developments to overcome the challenges.
Extending a bit further into the spatial processing domain, antenna diversity concepts were realized, and the ideas of multidimensional signal processing started to permeate wireless communication systems. As with many other areas of technological advancement, the pace accelerates once a new door is opened. In something of a convergence of digital signal processing power and algorithm development, fully adaptive multidimensional signal processing has now made its way into wireless communication systems and is providing substantial benefits. It is sometimes referred to as Spatial Division Multiple Access (SDMA) technology, a technology with roots in various defense-related development programs, which, among other companies, ArrayComm is currently productizing in its IntelliCell™ line of products.
SDMA technology employs antenna arrays and multi-dimensional nonlinear signal processing techniques to provide significant increases in capacity and quality of many wireless communication systems. It is especially well-suited to the current and next generation cellular systems termed Personal Communications Service (PCS). Antenna arrays coupled with adaptive signal processing techniques employed at base stations improve coverage, capacity and trucking efficiency allowing lower cost deployments with cells of moderate to large size. This talk will be an overview of past and present algorithms employed in smart antenna systems, and a look at what the future might bring in this area. A general discussion of the efficacy of the various approaches to different applications will be presented. Results from field trials demonstrating the efficacy of these systems will be presented along with a video demonstration time permitting.
Bio: Dr. Roy received his B.S. EE and B.S. Physics degrees from M.I.T. in 1972, an M.S. Physics degree from Stanford in 1973, and the M.S. EE and Ph.D. EE degrees from Stanford in 1975 and 1987 respectively. His Ph.D. research was in the field of digital signal processing, specifically estimation and parameter identification. Dr. Roy has been involved in the intelligence industry while with ESL/TRW, the oil-well services business, and the aerospace industry over the last twenty years. From 1975 through 1993, he was also a member of the Information Systems Laboratory at Stanford University as a graduate student and a research associate, and was also a consultant to industry working in the areas of parameter estimation and system identification with applications to control and communications systems during that time.
In April of 1992 he cofounded ArrayComm, Inc., a California corporation involved in the development of intelligent antenna products based on its proprietary SDMA technology for wireless telecommunication applications. ArrayComm currently has several smart antenna-based products on the market and is in the process of developing others. The company currently has strategic relationships with several of the world's largest telecommunications firms and is widely recognized as one of the leaders in its field.
Dr. Roy currently serves as Chief Technical Officer of ArrayComm. He is widely published internationally and holds several patents in the area of intelligent antenna technology and wireless telecommunications.
May 19, 1999: "Developments in the Characterization of Mobile Radio Propagation Channel" by Peter S. Rha, SFSU
Abstract: The characterization of radio wave propagation in the mobile environment is not an exact science, to say the least, and no analytical solutions exist, of the type that exist for guided structures of waveguide or optical fiber. The reasons are simple - the physical and electrical structures of the mobile channel are enormously complex and their characteristics would also change in time for the mobile in motion. Thus, most of the characterization models and methods are obtained empirically based on field measurements. Furthermore they are formulated primarily to understand the statistics in the received signal from the point of view of optimum communication system design, rather than to understand the physical mechanisms of propagation. So, in order to appreciate the channel characterization techniques used and their developments over the years, one has to understand how its main driving force, namely the cellular/PCS technology, has progressed and evolved over the years.
There are primarily two aspects in the operation of cellular/PCS systems in which the consideration of channel characteristics have major importance. One aspect has to do with the communication link level design; such as the multiple access methods and the modulator-demodulator (modem) design. And the other aspect has to do with the cellular network planning and engineering; such as the frequency reuse, cell coverage or outage probabilities, antenna configuration design, and handoff strategy. The two aspects are, of course, closely related. For example, determining which frequency reuse pattern to use in cell planning is directly dependent of the performance of the particular communication system design, namely the minimum signal to noise ratio or bit-energy to noise-density ratio required for an acceptable quality link.
This talk will discuss the evolution of the cellular/PCS technology from the first-generation, analog AMPS (Advanced Mobile Phone System), to the second- generation digital TDMA (Time Division Multiple Access) and CDMA (Code-), and to the currently under development third-generation CDMA. The emphasis in the discussion will be on those aspects related to propagation channel characteristics and the channel models typically employed in the celllular/PCS industry.
Bio: Peter S. Rha is Associate professor of electrical engineering at San Francisco State University. He specializes in cellular/PCS communication systems and RF engineering. Before joining SFSU, he has held various engineering and management positions with major companies in the cellular/PCS industry: first with AT&T Bell Labs in 1986, next with Hughes Network Systems, and most recently with Samsung Telecommunications America. Dr. Rha was Director of Systems and Hardware Development in his last position with Samsung, where he was the principal architect of the compact IS-95 CDMA base station trademarked as 'PicoBTS'. His experience in the industry include product development, systems engineering, and standards participation, with all major cellular/PCS technologies (i.e., AMPS, IS-136 TDMA and IS-95 CDMA). He has also taught while working in industry as an adjunct professor at the New Jersey Institute of Technology and Santa Clara University.
April 21, 1999: "Pulsed Antenna Measurement" by John Swanstrom, Hewlett Packard
Abstract: Antenna development continues to change, with a push towards higher performance antennas. Active transmit/receive (T/R) modules have enabled manufacturers to build active array antennas with many different beams and significantly improved performance. These newer higher-performance antennas present challenges for performance verification and testing not previously encountered in CW antenna measurements. Some of the challenges include:
- testing while in pulsed operating mode,
- testing all of the multiple beam states quickly,
- testing in both a high power transmit mode and a low power receive mode, and
- controlling the active array AUT as required by the test process.
Several types of pulsed measurements can be made on antennas. For active arrays operating in their pulsed mode, they fall into two categories: short-pulse high-PRF operation, and long-pulse low-PRF testing. A third type, pulse gating can be utilized on an antenna range to eliminate the ground bounce or other undesired transmission/reflection paths. Finally, pulse profiling can be used to look at the transmitted pulse from the active array, and determine the actual shape of the pulse, allowing designers to look for ringing and droop on the pulse.
This talk examines each type of pulsed antenna measurement, and the considerations and requirements for each. Instrumentation techniques and configurations that can be used for each type of measurement are presented.
Bio: John Swanstrom received his BSEE degree from the University of Illinois in 1974. After graduation, he worked in the antenna design group at Rockwell International (Anaheim CA) for eleven years. In 1985 he joined Hewlett-Packard as an applications engineer, and for the past 11 years has focused exclusively on antenna test measurement applications. A member of the Antenna Measurement Techniques Association for the past 15 years, he has authored 10 papers related to antenna measurement applications.
March 24, 1999: "SOME APPLICATIONS OF MODEL-BASED PARAMETER ESTIMATION IN ELECTROMAGNETICS" by Dr. Ed Miller
Abstract: Science began, and largely remains, an activity of making observations and/or collecting data about some phenomenon in which patterns may be perceived and for which a theoretical explanation is sought in the form of mathematical prescriptions. These prescriptions may be non-parametric, first-principles, or generating models (GMs), such as Maxwell's equations, that represent fundamental, irreducible descriptions of the physical basis for the associated phenomena. In a similar fashion, parametric fitting models (FMs) might be found to provide a reduced-order description of various aspects of the GM or observables derived therefrom. This talk will briefly summarize the development and application of exponential series and pole series as FMs using a procedure called model-based parameter estimation (MBPE).
MBPE provides a way of using data from a GM or from measurements to obtain the FM parameters. The FM can then be used in place of the GM for subsequent applications to decrease data needs and computation costs. An especially important attribute of this approach is that windowed, overlapping FMs make it possible to adaptively minimize the number of samples needed of an observable to develop a parametric model of it to a prescribed uncertainty. The adaptive approach can also provide an estimate of the data rank so that the FM order can be maintained below some threshold to improve the FM accuracy. These basic ideas are described here together with some representative applications to demonstrate their implementation.
Bio: Edmund K. Miller earned a B.S.E.E. at Michigan Technological University and a M.S.Nuc.E., M.S.E.E. and Ph.D.E.E. at the University of Michigan. His work experience includes the Radiation and High Altitude Engineering Laboratories of the U. of Michigan, Lawrence Livermore and Los Alamos National Laboratories, and MBAssociates, Rockwell International Science Center and General Research Corporation. He has been a physics instructor at Michigan Technological University, a Regents-Distinguished Professor at the University of Kansas and a Stocker Visiting Professor at Ohio University. He has also served as a Guest Scientist at the University of Pretoria and University of Stellenbosch, both in the Republic of South Africa. He is presently actively retired in Santa Fe, NM.
He has served two terms on IEEE AP-S AdCom, has been an AP-S Distinguished Lecturer, initiated and chaired the ad hoc AP-S Committee on ElectroMagnetic Modeling Software, and chaired the AP- S Education Committee during which time he organized the first short courses given at AP-S Symposia. His column "PCs for AP and Other EM Reflections" has appeared in the AP-S Newsletter/Magazine since 1985. He has served on numerous AP-S Symposium Committees, chaired the Program Committee for the 1977 Symposium, has organized several special sessions for the yearly symposia and has organized two AP-S Workshops on Software Validation. He was elected IEEE Fellow in 1994.
Dr. Miller has edited "Time-Domain Measurements in Electromagnetics" and co-edited the IEEE-Published reprint book "Computational Electromagnetics: Frequency Domain Method of Moments." He was the recipient (with co-authors) of the 1988 Best Paper Award from the IEEE Education Society. He has served on the Editorial Board of IEEE student magazine POTENTIALS since 1985 serving as its Editor 1992-1995. Other editorial boards on which he serves include the IEEE Computer Society Computational Science and Engineering Magazine, Radio Science, the ACES Journal, the Journal of Electromagnetic Waves and Applications, Computer Applications in Engineering Education and Electromagnetics. Other activities include serving as the first President of ACES and two terms on the ACES Board of Directors, serving as Chairman of US Commission A of URSI, and membership in US Commissions A,B,C and F of URSI. His primary interests remain focused on computational electromagnetics, applied signal processing, visual electromagnetics, and promoting the incorporation of accuracy statements in CEM numerical results.
February 17, 1999: "Radome Design and Installation " by Wally Downs
Abstract: The name "Radome" covers a variety of items ranging in size from a fraction of an inch to structures over a hundred feet in diameter. A radome can best be defined as anything that covers an antenna. Since antennas vary greatly in size, frequency and operating conditions, the subject of radomes design, choice of materials and operational environment frequently present challengers to engineers.
The presentation will cover the geometric design of spherical and geodesic radomes, showing that there is a logical plan to the design of these multi-panel structures. Some highlights of experiences encountered during the installation of some of these radomes in Korea, the Mojave Desert, Puerto Rico, and the South Pole will be recounted.
There will be a discussion of materials used in radome construction, taking into consideration the thickness, frequencies involved, and types of sandwich structures. There will also be a discussion of FSS (Frequency Selective Surfaces) involved in radomes and dichroic subreflectors.
Bio: Wally Downs has been building radomes and antenna reflectors for thirty five years, the past twenty of which have been in Santa Clara with Pacific Radomes, Inc. All of the products of Pacific Radomes involve RF which either passes through or is reflected from their surfaces. In the case of dichroic surfaces it does both.
January 20, 1999: "ERROR ANALYSIS AND REDUCTION TECHNIQUES FOR PLANAR NEAR FIELD RANGE ANTENNA MEASUREMENTS" by L. J. Kaplan, W. G. Scott, and R. E. Wilson
Abstract: This three part talk will begin with a description of the planar near field range (NFR) and its operation to obtain far field angle patterns from measured near field amplitude and phase data.
The second part will review the comprehensive error measurement and analysis process which can be done on a near field range. Because all error sources can be evaluated on a NFR it is possible to identify the largest sources and subsequently to minimize the worst ones, if necessary. As a result of this complete error procedure the NFR category (including planar, cylindrical and spherical scanner types) is now generally acknowledged to be capable of better accuracy than other types such as the far field range or the compact range.
The third part will describe the "quadrille", a new technique for minimizing two of the typically largest NFR error sources, room scatter and antenna-under-test(AUT) / probe coupling. Coherent processing using measurements on two probe scan planes with different (AUT)-to-probe separations reduces the effects of coupling between the AUT and the probe or, alternatively, reduces the effects of room scatter. These doublet scans can be coherently combined to mitigate one or the other (but not both) of these error terms. For either case, the extraneous signals cancel when the far field patterns from the two planes are coherently combined. The new "quadrille" scan technique coherently combines four separate scan planes to cancel both the AUT-probe coupling and the room scatter errors. If either the coupling or the room scatter is much larger than the other, in some cases the error reduction attained by the quadrille may not merit the additional measurement time; however if the two terms are comparable the quadrille may be needed to attain precise measurements. This talk is a revised version of a paper presented at the 1997 AMTA Symposium in Boston.
Bio: Len Kaplan received the BEE and the MEE degrees from New York University. He stayed at NYU as a research associate after receiving his undergraduate degree working mainly on microwave circuit theory. His industrial experience has involved the application of electromagnetic theory to antennas and radar scattering, and the analysis of communication and detection devices. He has worked at the MITRE corporation, Sanders Associates, AVCO Everett Research Laboratory, Raytheon, SRI, Lockheed, and presently at Space Systems/Loral (SS/L). He is the co- author of about 30 technical papers, letters, and symposium presentations. His work on near field antenna measurements began at Raytheon in 1977 and was renewed at SS/L.
Bill Scott received the BS degree in Physics from the University of Missouri in 1952 and took graduate physics courses at The George Washington University and the University of Virginia. He worked in antenna engineering at Melpar, Inc. in Falls Church, VA from 1954 to 1960 when he joined the Aeronutronics Division of Ford Motor Company Newport Beach, CA heading the antenna and radar scatterer development section. In 1972 he transferred to the Space Systems Division of Philco Ford Corp. in Palo Alto, CA, working on antennas for communication satellites. He is still with this organization, now a part of Space Systems/ Loral in Palo Alto. In 1992 he procured a large near field range test facility for the antenna engineering department and has been in charge of its operation since then. He has authored or co-authored 35 technical papers in various journals and symposia and served the APS in several positions.
Richard Wilson received the BSEE degree from the University of Missouri in 1977 and the MSEE degree from the Georgia Institute of Technology in 1978. He continued on at Georgia Tech doing advanced graduate work in the area of applied electromagnetics. While at Georgia Tech, first as a research associate and later as a research engineer, he worked on numerical analysis of power grounding grids, radomes, and dish and phased array antennas. His work in the area of antenna measurements, included helping with the instrumentation of the EE departments spherical near-field range, research on measurement techniques using this range, and analysis for the design of the compact range at the Army?s Fort Huachuca. In 1995 he joined Space Systems/Loral (SS/L) working in their large planar near-field range. He is the co-author of 36 journal and conference papers, 8 major research reports and chapters in 2 books.