Showing papers in "IEEE Microwave Magazine in 2003"

Ultra-wideband wireless systems

Abstract: The recent FCC frequency allocation for UWB has generated a lot of interest in UWB technologies. There is 7,500 MHz of spectrum for unlicensed use. The main limitations are provided by the low-power spectral density and by the fact that the transmit signal must occupy at least 500 MHz at whole times. IEEE 802.15.3a is being developed for high-bit-rate PAN applications, and UWB is the most promising technology to support the stringent requirements: 110, 200, and 480 Mb/s. Two UWB multiband systems, frequency hopping and Spectral Keying, have been described in this article. Both systems meet the stringent requirements provided by IEEE 802.15.

Passive millimeter wave imaging

Abstract: This article introduces the concept of passive millimeter-wave (PMMW) imaging, describes the phenomenology that defines its performance, explains the technology advances that have made these systems a reality, and presents some of the missions in which these sensors can be used.

Wireless local positioning

Abstract: Local positioning will be one of the most exciting features of the next generation of wireless systems. Completely new concepts and features for wireless data transmission and transponder systems will emerge. Self-organizing sensor networks, ubiquitous computing, location sensitive billing, context dependent information services, tracking and guiding are only some of the numerous possible application areas. This article introduces different concepts of several existing and emerging systems and applications.

Enhancing homeland security with advanced UWB sensors

Abstract: This article discusses recent research into short-range UWB radars that have the potential to create more robust perimeter security sensor systems for exterior installations. It also briefly discusses existing UWB sensors to show how they establish a technical precedent for today's research.

A review of thin-film resonator technology

Abstract: Thin-film resonator technology has been under development for over 40 years as a means to reach higher frequencies than obtainable with conventional quartz-crystal technology. Using advances in microelectronic processing, thin films of piezoelectric materials are used to fabricate resonators and filters over a range of 500 MHz to 20 GHz. This article is a review of the thin-film resonator (TFR) technology that describes the core structures and issues and gives examples of filters and resonators that have been manufactured or demonstrated.

Application notes - basic parameters of coplanar-strip waveguides on multilayer dielectric/semiconductor substrates, Part 1: high permittivity superstrates

Abstract: A simple method and closed-form analytic formulas for symmetric CPS based on single layer substrate (infinite and finite thickness) and multilayer lossy dielectric (semiconductor) substrate, where the permittivity of the superstrate layers decrease away from the strips, are proposed. Since the line models are given analytically, the dependencies of the line parameters may be analyzed and optimized in wide ranges of sizes, permittivities, and losses (substrate resistivity). In general, the formulas are reversible. The measured line parameters may be used to calculate the permittivity and loss tangent (resistivity) of one of the substrate layers if the parameters of the other layers and strips are known. The method may be easily extended to include larger number of substrate layers.

Safety standards for human exposure to radio frequency radiation and their biological rationale

Abstract: Exposure guidelines for RF radiation have been promulgated for nearly half a century. However, our understanding of biological effects of exposure to RF radiation is still evolving and more so for cellular mobile telephones and wireless personal communication devices. There are two different sets of guidelines promulgated for limiting human exposure to RF radiation, worldwide. Currently, there is a backdrop of persistent, publicly expressed lack of confidence in radio-frequency (RF) exposure standards, pertaining to the maximum permissible exposure (MPE) level of humans exposed to RF electromagnetic radiation. Much of the current effort is driven by the advent of cellular mobile telephony, which uses RF radiation in the range of 800-2,500 MHz. The setting of guidelines or standards for maximum permissible levels of exposure to RF and microwave radiation is a valid approach to managing the risk of such exposures. The existing guidelines, however, are based on results obtained from acute, short-term studies that are atypical of the RF exposures associated with the handset of cellular mobile telephones. For the first time in human history, a source of RF radiation is located right next to the head of millions of cellular mobile telephone users. Biological effects after repeated, prolonged, or lifelong exposure to RF energy emitted by these low-power wireless telecommunication devices have been investigated only during the past few years. The existing scientific results are equivocal and arguable in many respects. Consequently, there remains a widespread public concern about the adequacy of existing guidelines in safeguarding the general population against possible harm of RF radiation from cellular mobile telephones.

SAW-based radio sensor systems for short-range applications

Abstract: Wireless autonomous surface acoustic wave (SAW) sensors offer high flexibility for modern sensor systems. Because no battery or wiring is required for power-supply and communication tasks, they can be advantageously employed for nearly all kinds of short-range identification and measurement applications, where the use of conventional sensors, e.g., on moving or rotating parts or in industrial process chambers. Here, the basics of SAW-based radio sensor systems are reviewed and different examples out of a manifold of possible applications are given. Wireless SAW identification and sensor systems operate stable and maintenance free over many years even in harsh industrial environments. With a fast readout of only a few microseconds, a readout-distance of up to several meters, and a high sensor stability, even at temperatures above 200 /spl deg/C, these highly flexible SAW-based radio systems are ideally suited for a multitude of measurement tasks in industrial, automotive, transportation, and domestic applications.

Basic parameters of coplanar-strip waveguides on multilayer dielectric/semiconductor substrates. Part 2: Low permittivity superstrates

Abstract: For Part 1 see ibid., vol.4, pp.67-70 (2003). In Part 1, closed-form formulas were proposed for basic parameters of coplanar-strip (CPS) waveguides on multilayer dielectric substrates. In Part 2, a new partial capacitance technique is proposed to deal with the case where the permittivity of the substrate layers increase away from the strips, and the magnetic wall approximation between the dielectric layers used in Part 1 is not valid. CPS on a SiO/sub 2//Si substrate is a typical example. Conformal mapping technique is also used for the evaluation of the line inductance (including internal) of the strips. The line capacitance, inductance, and conductance are then used to evaluate the frequency-dependent complex impedance, effective dielectric permittivity, and losses. The results are in good agreement with experiments and numerical simulations. The computation time is at least an order of magnitude shorter in comparison with the available commercial software (e.g., Momentum, Sonnet).

Advanced Techniques in RF Power Amplifier Design [Book Review]

Abstract: Advanced Techniques in RF Power Amplifier Design is the second book on power-amplifier design by Steve Cripps. His first book, RF Power Amplifiers for Wireless Communications (or RFPA), was a thoughtful tour of power-amplifier design with some discussions on advanced design techniques. This book complements the first book with more detailed discussions of power-amplifier architectures and semiconductor device design for power amplifiers. Advanced Techniques is an insightful and refreshing look into the latest power-amplifier design and analysis techniques for high efficiency and linearization. This book also serves as one of the better tutorials on those techniques. Dr. Cripps’ writing is engaging; his analysis uses basic mathematical models and works through them in detail to give the reader insight into the problems at hand. Advanced Techniques avoids extensive numerical analysis and provides a different perspective on amplifier design. This book is worth reading for anyone doing or teaching power-amplifier design. Apparently, Dr. Cripps developed Advanced Techniques from his engineering work and his recent short courses. Advanced Techniques is not about bias circuits or the latest trend in matching network synthesis, but it is a practical book on building power amplifiers for high efficiency or high linearity. Chapter 1 is an overview of Class AB amplifier operation with a discussion of bipolar transistors and linearity issues. The idealistic transistor models used in many treatises are shown to have significant faults for nonlinear analysis. Dr. Cripps also comments that his earlier work was more oriented toward field-effect transistors and silicon-germanium transistors have made bipolar transistors an attractive technology alternative these days. The rest of the book is a collection of power-amplifier topics and techniques. This book is not a comprehensive treatment of any aspect of power-amplifier design but rather a careful look into the assumptions and problems that face power-amplifier designers. Chapter 2 takes a fresh look at the Doherty and Chireix high-efficiency amplifier strategies and finds some common ground between the two techniques. A recurring theme in this book is limitations in previous analysis. Dr. Cripps points out many issues with prior analysis and tries to clarify the various uses and limitations of previous work. Chapter 3 covers many aspects of the multitone analysis needed for multicarrier amplifiers and amplifiers with more complex modulation schemes. Chapter 4 focuses on feedback distortion reduction and how amplifiers can be designed to minimize path delay for wider feedback bandwidth. This leads into Chapter 5’s discussion of predistortion techniques. While a great deal has been written on polar and cartesian feedback systems in recent years,

RF CMOS come of age

Abstract: Radio-frequency integrated circuits (RFICs) in complementary metal-oxide semiconductors (CMOS) are developing a strong presence in the commercial world. They are dominant for applications such as wireless LAN and Bluetooth and are making inroads into areas such as global system for mobile communications (GSM) cellular transceivers and global positioning system (GPS) receivers. This article offers a brief retrospective on how RF circuits and systems in CMOS have evolved to their current state of the art, followed by perspective of what the future might hold for RF systems on a chip (SOC) in CMOS. It seems appropriate today, roughly ten years after the first publications reporting RF circuits in CMOS, to document the key developments and first reports of the circuit techniques and architectural innovations that are now in widespread use for the development of a new generation of RFICs.

Planar electromagnetic analysis

Abstract: Electromagnetic (EM) analysis has been in regular use in the design of planar high-frequency and microwave circuits for well over a decade. This article provides a brief historical background of this development, a description of recent developments, and a speculative look at the future.

Electromagnetic modeling and analysis of wireless communication antennas

Abstract: The goal of this article is threefold: to present the basic principles of the application of method of moments (MoM), finite-difference time-domain (FDTD) and finite-element method (FEM) to analysis of antennas; to present examples of antenna simulations that show the capabilities of some modern commercially available simulators; to discuss future trends in modeling and analysis of microwave and millimeter-wave antennas for wireless communications.

Cataracts and personal communication radiation

Abstract: The induction of cataracts or formation of lens opacity in the human eye has often been incriminated as a possible hazard of human exposure to personal communication radiation and microwave radiation in general. In the case of cell phones, some concerns have been expressed when the user holds the cell-phone handset, or the microwave radiating device, directly in front of the face, exposing the eye to a straight-on incidence of the cell-phone radiation.

Early quasioptics of near-millimeter and submillimeter waves in IRE-Kharkov, Ukraine: from ideas to the microwave pioneer award

Abstract: This paper is about the early quasioptics of near-millimeter and submillimeter waves in IRE-Kharkov (Institute of Radio Physics and Electronics of the National Academy of Sciences of Ukraine) and the development of the hollow dielectric beam-waveguide (HDB) technology and measuring techniques of the near-millimeter and submillimeter wavelength ranges, with main application in hot plasma diagnostics. It presents the details of the development based on the declassified reports and the interviews of Y.M. Kuleshov and another key member of the quasioptics (QO) team, M. S. Yanovski. Y.M. Kuleshov and his team had already accumulated rich experience in developing waveguide measuring devices in the whole millimeter-wave range between 1954 and 1961. In 1994-1996, the research project "Ozero" was carried out with Y.M. Kuleshov as a principal investigator. The aim of the "Ozero" was to explore the feasibility of developing a kit of HDB-based measuring devices in the wavelength range /spl lambda/ = 0.7 to 1.7 mm. After the finish of "Ozero", in 1968-1971, the next R&D project called "Oliva" was granted by the same directorate of MRI. Its idea was to dwell on and refine the polarization principles in the measuring circuits for /spl lambda/ = 0.5-0.8 mm. HDB was patented only in 1969. Since the 1970s, the activities of the QO department were focused entirely on the development of HDB-based instruments and systems. Here, the major application area was hot plasma diagnostics in new large Tokamaks. They also dwelled in the development of the measuring techniques including reflectometry and polarimetry. Other HDB based systems elaborated in IRE include radars in the 1970-1980s and RCS testing ranges in the 1990s.

Health effects - effects of cell-phone radiation on lymphoma-prone mice

Abstract: Discusses the incidence of lymphomas in mice following long-term exposure to pulse-modulated microwave fields similar to those used in digital cellular mobile telephones. The mice are predisposed to developing lymphomas spontaneously.

Simulating circuits and devices

Abstract: The successful engineering realization of high-frequency components and systems for these applications is heavily dependent on computer-aided design (CAD) in numerous respects. There are many different types and levels of modeling and simulation that may be involved, but the following discussion focuses on device modeling and circuit simulation, while also trying to place these within the wider high-frequency, computer-based design context, where possible. Furthermore, much of modern high-frequency design is driven by monolithic microwave integrated circuit (MMIC) technology and the greater levels of integration made possible using this technology. Accordingly, in this short overview of microwave device modeling and circuit simulation, we restrict our attention primarily to MMIC-based design.

Risks to children from cellular telephone radiation

Abstract: Are children more vulnerable to the microwave radiation from cellular mobile telephones? It is an open question. The paucity of laboratory results should make anyone hesitate in making definitive remarks on the health and safety of mobile-phone radiation on children. On the other hand, there have been plenty of computational studies on deposition of mobile-phone radiation or the specific absorption rate (SAR) in head models of youngsters and adults.

Quantifying the benefits of enhanced filter selectivity

Abstract: Today's mobile communications market is very competitive, with wireless service providers making every effort to improve the performance of their network to retain subscribers. Coupled with the proliferation of radio-frequency signals in the environment due to the growth of all forms of wireless communication, this leads to a very challenging task - namely, to provide ubiquitous high-quality service in spite of ever-increasing interference levels. One of the tools at the disposal of the network operator to provide such service is a cryogenically cooled receiver front end for base stations, wherein each receive path consists of a high-temperature superconducting (HTS) bandpass filter followed by a cryogenically cooled low-noise amplifier. There are two primary benefits achieved by the use of this front end. The first is improved receiver sensitivity through the reduction of electrical noise generated by the front end itself. The second is the significant reduction in the effects of out-of-band interference through the highly selective filtering made possible by the use of HTS materials. While this paper addresses both receiver-sensitivity and filter-selectivity benefits, the focus is on improved out-of-band interference rejection through enhanced filter selectivity.

A simple interstage matching technique for designing hybrid microwave power amplifiers

Abstract: A non-50-/spl Omega/ interstage matching technique has been used for designing multistage microwave power amplifiers. The technique is especially relevant to cases where the final stage uses an LDMOS device whose dynamic input impedance is extremely low and is best matched directly (without first translating to 50 /spl Omega/) to the output of the previous stage. A specific example is presented. The concept, however, is quite general and will be of interest to the RF design community at large.

Accurate modeling of monolithic inductors using conformal meshing for reduced computation

Abstract: Accurate component modeling is a key factor to successful wireline and wireless circuit design in Si/SiGe BiCMOS and RF CMOS. This article presents the application of two planar electromagnetic simulation methods for reducing the memory and computation time requirement for accurate simulation of inductors fabricated with thick analog metal layers. First, a conformal subsectioning technique is briefly discussed in the context of reducing the numerical complexity of octagonal and circular spiral inductor analysis. Second, this article discusses a method for determining if more than a two-sheet model of thick metals is needed for accurate inductor simulation. Finally, the conformal mesh is applied to a 3.3-nH inductor fabricated using the IBM 0.13-/spl mu/m RF CMOS process technology. The simulated and measured results are compared.

A nobel prize in microwave engineering

Abstract: As this issue goes to print, the announcements of the various Nobel Prizes have been prominently featured in the news, and have highlighted the scientific advancements in their respective fields. Such public attention, brought to a scientific work by the award of a Nobel Prize for it, can hardly be matched by anything else, even if over the years the works recognized by these awards have ranged from very significant to obscure, and do not always seem to qualify as a "service to the mankind" that Alfred Nobel envisioned in his will. Service alone is not enough - the microwave oven probably serves mankind close to a billion times a day, but lacks the intrigue of fundamental particle physics. Apparently, one way to bring the accomplishments of microwave engineers to the attention of general public would be to institute a "Nobel Prize in Microwave Theory and Techniques." It is argued that the IEEE Microwave Theory and Techniques Society Awards are as close as one can come to a Nobel Prize in microwave engineering. The Society invites nominations for a number of awards described on its Web site, and the nominations for the year 2003 are presently open.

Wireless investor - triple-screen investing

Abstract: Markets often focus on the short- and medium-term view. While it is too early to be wildly bullish, it may be time to start picking cautiously through the post-crash rubble. This column describes investment strategies that may be appropriate for this phase of the market. This column presents a triple-screen system for investing in a diversified portfolio of stocks.

Taking the grind out of grinding

Abstract: Existing uses of RF/microwave heating involve soft targets. This article focuses on current research being carried out in the United Kingdom and South Africa, where microwave energy is being applied to "soften up" rocks for the purpose of mineral extraction.

Value averaging

Abstract: It makes sense to retain some broad exposure to stocks during a secular bear market, providing one is willing to take medium-term profits. This article presents a strategy called value averaging, which harvests medium-term profits. Value averaging is a modified form of dollar cost averaging. Both strategies are examples of "formula investing.".

Some thoughts on microwave education

Abstract: In this issue, we have an interesting article by Dr. Jim Rautio. Jim was one of the panelists for the panel session on “The Future of Education in the Area of Microwaves” during IMS 2003, held in Philadelphia, Pennsylvania, in June. This brief article entitled “Some Thoughts on Microwave Education” is an extension of the thoughts he shared in panel discussions. Also, in this issue we recognize winners of MTT-S Undergraduate/Pre-graduate Scholarships for 2003–2004 session. Some Thoughts on Microwave Education “Love,” is how Bruce Eisenstein described it at the panel session on microwave education at IMS 2003. As with a young man’s fancy, we cannot force students to share our love of technology and science in general or of microwaves in particular, but we can provide an environment that will at least give us a chance to share our love if, by chance, it is meant to be. In spite of having spent several years as a professor long ago, I am not a professional educator. Even so, I was also invited to sit on this panel. Perhaps an outside and unconventional viewpoint was desired. After the panel session, the organizer, K.C. Gupta, asked that I write up some of my ideas. So please feel free to ignore, modify, or even actually use any of my suggestions. I fell in love with technology as a young boy growing up on a farm. My father, who had not graduated from high school, had somehow put together a ham radio station prior to WWII. I was intensely curious about how the maze of wires, tubes, and equipment worked. Soon, I had a ham license, and in the midst of a period of widespread unemployment among engineers, I decided I wanted to become an “electrical engineer,” even though no one in our family had ever gone to college and the financials were daunting. However, farming was now no longer my future. My route to college was necessarily indirect, but my intense love saw me though various difficulties, eventually yielding a Ph. D. and building a small but successful microwave software company. My suggestions are based on that journey. First, teach your students about more than just the equations. For example, when teaching Maxwell’s equations, point out that Maxwell made two original contributions: displacement current and the creation of a firm mathematical basis for the entire theory of

How many biologists does it take to fix a radio

Abstract: As a member of MTT-10, the technical coordinating committee on “Biological Effects and Medical Applications,” I find it natural to take occasional peeks into the world of biology. The year 2003 is a particularly auspicious year for doing so, because it marks the golden anniversary of the discovery of the double-helix structure of the DNA molecule. That monumental find by Crick and Watson led to the astounding progress we have seen in the field of molecular biology, culminating recently in the sequencing of the human genome [1]. As Thomas Kuhn noted in his 1962 classic, The Structure of Scientific Revolutions, the bulk of science proceeds within a given framework (a “paradigm”) for certain historical reasons. The Crick-Watson discovery injected into biology a reductionist paradigm, whereby subsequent scientific progress was gauged by [1] “describing the smallest bits possible, usually one at a time—one stretch of DNA, one RNA, one protein.” How does the future of biology look? As a cover story [2] in Time put it earlier this year, “Cracking the DNA code has changed how we live, heal, eat and imagine the future.” However, not all biologists are as sanguine about the usefulness of the prevailing reductionist paradigm for the 21st century. Yuri Lazebnik, a molecular biologist, offers a contrarian view in a letter [3] he wrote to Cancer Cell. There, he explores the potential pitfalls inherent in the current reductionist approach used in biology, by applying it to the problem of fixing a broken transistor radio, a reasonably complex but wellunderstood system. Lazebnik starts with the premise that biologists, given their generally feeble knowledge of physics, will look at a radio essentially as a black box that is supposed to play music. Now to figure out how to troubleshoot this complex box, they would start out by securing grants to buy a large supply of identical functioning radios. After cataloguing the various components (“square metal objects, a family of round brightly colored objects with two legs, roundshaped objects with three legs, and so on”), they may shoot the radios at close range and select those for further analysis that develop a malfunction. This may lead to such crucial discoveries as the Most Important Component (the connection between the external FM antenna and the radio) or the Really Important Component (the connection between the internal AM antenna and the radio) or, to the chagrin of the previous two discoverers, the Undoubtedly Most Important Component (the AM/FM switch). Lazebnik ponders: