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MTT-S Distinguished Microwave Lecturer Program Lecturers Emeritus
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Gabriel Rebeiz (Term Ended December 2004) Electrical Engineering
and Computer Science, (email contact is preferred) |
Application of
MEMs Technology to RF/Microwave Systems
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Wireless Access Using Microwave Photonics Development of the core communications network through dense wavelength division multiplex technology has led to massively increased transmission capacity, with many internet connections running at less than 20% utilisation. However the provision of broadband (> 2 Mb/s) access has been relatively slow and expensive, particularly broadband wireless access. In this talk, the use of wireless over fibre technology to facilitate broadband wireless access will be discussed. Currently deployed narrowband cellular systems will be described, followed by, in turn, passive pico-cell approaches for in-building coverage, microwave and millimetre-wave systems for local area outdoor use. The technologies required will be illustrated from research programmes in Europe, the Asia-Pacific region, and the Americas. Finally, likely future developments in these systems will be described. |
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Christian Schaffer (Regional Lecturer) (Term Ended December 2004) University
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Microwave Photonics for Broadband Radio Systems The new emerging field of Microwave photonics can be defined as the study of the interactions between optical waves and high-frequency electrical signals. A number of applications is of increasing commercial importance i.e. distribution of microwave signals, optical beamforming in phased array antennas, optical delay lines and the generation of microwave signals. Different methods of generation and distribution of microwave signals up to 100 GHz for application in a broadband (>100Mbit/s) cellular radio system are presented. |
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Professor L E Davis (Term Ended December
2005) Dept. of Electrical Engineering & Electronics, University of Manchester Institute of Science and Technology (UMIST), t. +44-(0)161-200-4685
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Modern Circulators and Isolators for Wireless and Automotive
Applications
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Professor Wojciech Gwarek (Term Ended December 2005)
Politechnika Warszawska, t. +48-22-6607631 |
Microwave passive circuit design without hardware prototyping – how close it comes with state-of-art electromagnetic simulation
The lecture will start with a review of different electromagnetic simulation methods and their ability to deal with specific problems, as well as their accuracy versus applied computer resources. The theory will then be illustrated with examples of design based on time-domain electromagnetic simulation. The influence of various simulation parameters on obtained results will be discussed in detail. The actual set of examples will be adjusted to the profile and interests of the prospective audience. It may include such areas of applications as: waveguide components - polarisers, OMT's,diplexers, filters - transitions, junctions and couplings between different kinds of transmission lines, planar components (in microstrip and coplanar technologies), coaxial connectors, antennas and antenna feeding structures, dielectric waveguides and resonators, periodical (like slow-wave) structures, and quasi-optical components.
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Dr. Wolfgang Heinrich (Term Ended December
2005)
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Flip-Chip for Millimeter-Wave
and Broadband Packaging |
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R.J. Trew (Term Ended December
2005) NC t. +1-919-515-7350 |
Large-Signal Physical Operation of SiC and Nitride-based Microwave Field-Effect Transistors Wide bandgap semiconductors show great promise for advancing the state-of-the-art for high power microwave electronic devices. Primarily due to low breakdown voltage it has not been possible to design and fabricate solid-state transistors that can yield RF output power on the order of 100’s to 1000’s of watts necessary to compete with microwave vacuum tubes. This has severely limited the use of microwave solid-state transistors and devices in power applications, such as transmitters for wireless communications systems, radars, etc. Recent improvements in wide bandgap semiconductor materials technology provide the opportunity to now design and fabricate microwave transistors that demonstrate performance previously available only from microwave tubes. The most promising electronic devices for these applications are MESFET’s fabricated from the 4H-SiC polytype and HFET’s fabricated using the AlGaN/GaN heterojunction. These devices can provide RF output power on the order of 5-6 W/mm and 10-12 W/mm of gate periphery, respectively, and amplifiers in the kW range should be possible with power combining technology. 4H-SiC MESFET’s should produce useful performance at least through X-band, and AlGaN/GaN HFET’s should produce useful performance well into the mm-wave region, and potentially as high as 100 GHz. However, a variety of physical effects are currently limiting the application of these devices. The limiting effects are associated with various charge trapping, surface, and space-charge phenomena that affect device performance under large-signal RF operation conditions. Large-signal RF operation and engineering approaches to controlling these effects will be discussed.
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Joy Laskar (Term Ended December
2006)
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Recent Advances in High Performance Communication Modules and Circuits
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Microwave Applications of Metamaterials and Structures Metamaterials are artificial or man-made structures that have properties not found in naturally existing materials. The most unusual metamaterials are the Left-Handed ones, also called Double Negative or Negative Refractive Index materials, which are characterized by simultaneously negative permittivity and permeability. Many interesting EM propagation phenomena result from the negativeness of the constitutive parameters. For instance, the phase and the group velocities are anti-parallel in a Left-Handed substance. Fundamental theoretical research as well as research on possible revolutionary applications for microwave and RF circuits is underway at various organizations. Although the technology is still in its infancy, novel practical developments have already been proposed. The talk will contain a brief historical account, fundamental concepts, adaptation to microwave environment and several passive components with unique features. |
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Doug Rytting (Term Ened December
2006)
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Calibration and Error Correction Techniques for Network Analysis The accuracy of Vector-Network-Analyzer (VNA) measurements depends critically on calibration and error correction techniques. This talk will cover the evolution of conventional VNA calibration methods from the start of network analysis through the development of new calibration methods for waveform and large-signal analysis. Included will be the original SOLT (Short-Open-Load-Through) methods, the newer self-calibration techniques like TRL, LRL and Unknown-Thru, and the strengths and weaknesses of these various VNA calibration approaches. The talk will conclude with a discussion of new state-of-the-art extensions of the traditional VNA calibration strategy for calibrated waveform measurements at microwave frequencies capable of capturing the both the temporal and large-signal behavior of microwave and digital devices. |
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Michael Shur (Term Ended December 2006) Rensselaer Polytechnic
Institute, |
Microwave GaN based Field Effect Transistors Unique properties of GaN/AlN/InN and related semiconductors make them superior for high-power applications. Device physics and device design of GaN-based FETs are different from those for more conventional GaAs and InGaAs based transistors. In GaN/InN/AlN transistors, strain control and polarization effects are very important, and a new epitaxial technique (called MEMO-CVD), a novel strain energy band engineering (SEBE) approach, and quantum well designs have been developed to control strain, polarization, and non-ideal effects. Also, a very large sheet electron density at heterointerfaces in the GaN-based FET channels allows for a novel and unique insulated gate heterostructure design that has many advantages over more conventional heterostructure FETs. Special field plate designs can dramatically increase the breakdown voltage. As a result, high current values in GaN-based microwave field effect transistors can be combined with very high breakdown voltages, and these devices have potential of replacing traditional GaAs and InGaAs based microwave field effect transistors. |
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Wolfgang Hoefer (Term Ended December 2007)
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Multi-Level Modeling for Complex Microwave/High-Speed Design Complex communication and information systems operating in the Gigahertz range often combine multiple analog and digital functions. The design of such systems must capture all electromagnetic effects and interactions that impact their performance. However, it is impossible to model such systems globally at the field and device levels. Therefore, designers must take a hierarchical approach (top-down design) by which the system is conceived at a high level of abstraction and in behavioral terms. The specifications for its functional components are formulated at the network or circuit level. They, in turn, define a physical structure that requires frequency- or time-domain electromagnetic field analysis. Once the functional components have been realized, their actual physical behavior must be analyzed or measured, including possible parasitic interactions between them, and abstracted into realistic (as opposed to initially specified) behavioral models that accurately predict their impact on overall system performance (bottom-up verification). This methodology also addresses signal integrity, packaging, interconnects, electromagnetic compatibility (EMC), and thermal issues. The purpose of this lecture is to familiarize
our members with evolving design approaches for systems of large
technological and functional complexity, and to demonstrate how microwave
modeling and design practices can be integrated into a wider flexible
multi-level modeling
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Bumman Kim (Term Ended December 2007) Head and Professor Department of
Electrical Engineering |
Linear Power Amplifiers for Mobile Communication Systems Linear power amplifiers for base-station
application require high efficiency and good linearity. To achieve the
goal, the main research has two directions: high efficiency linear power
amplifier and error correction technique to further improve the linearity
of the amplifier. |
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James C. Rautio (Term Ended December 2007) Sonnet Software
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Maxwell, Life of James Clerk James Clerk Maxwell stands shoulder to shoulder with Newton and Einstein, yet even those of us who have spent decades working with Maxwell's equations are almost totally unfamiliar with his life and times. This presentation, from the viewpoint of a microwave engineer, draws on many sources in providing an understanding of James Maxwell himself. What was Maxwell like as an infant? What was the tragedy at eight years old that profoundly influenced his life? What unique means of transportation did young Maxwell use to escape a cruel tutor? What memorable event occurred on his first day of school? When did he publish his first papers, and what were they about? What did Maxwell have to do with the rings of Saturn? Why did he lose his job as a professor? Why did he have a hard time getting another job? What was his wife like? What is Maxwell's legacy to us? The answers to these questions provide insight into Maxwell the person and add an extra dimension to those four simple equations we have studied ever since.
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Peter Siegel (Term Ended December 2007) California Institute of Technology Jet
Propulsion Laboratory
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Terahertz Technology in Outer and Inner Space After more than 30 years of niche applications in the space sciences area, the field of Terahertz Technology is entering a true Renaissance. While major strides continue to be made in submillimeter wave astronomy and spectroscopy, the past few years have seen an unprecedented expansion of terahertz applications, components and instruments. Broad popular interest in this unique frequency domain has emerged for the first time, spanning applications as diverse as biohazard detection and tumor recognition. Already there are groups around the world who have applied specialized Terahertz techniques to disease diagnostics , recognition of protein structural states , monitoring of receptor binding , performing label-free DNA sequencing and visualizing contrast in otherwise uniform tissue . A commercial terahertz imaging system has recently started tests in a hospital environment1 and new high sensitivity imagers with much deeper penetration into tissue have begun to emerge . Solicitations for more sophisticated instruments and enabling terahertz components have filtered into US agency proposal calls from DoD and NASA, to NSF and NIH, and many new research groups have sprung up, both in this country and in Europe and Asia. This talk will broadly survey terahertz technology from its cradle applications in space science and spectroscopy to more recent biomedical and chemical uses.
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