bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency Standards, Characterization
Authors: Ferre-Pikal Eva S. , Walls Fred L.
Published: April 2005

We describe the characterization of frequency standards following the general definitions accepted by the IEEE, the International Telecommunications Union—Radiocommunications (ITU‐R), and the International Radio Consultative Committee (CCIR). We describe what is meant by accuracy and frequency stability of a frequency standard. The variations in frequency (which define the frequency stability) can be classified into two basic types: random and systematic. To characterize random variations in frequency, the systematic effects must be removed from the data. Special statistical techniques other than the standard variance must then be used to quantify random variations in frequency because some of the noise processes are not stationary. As part of the statistical treatment, we describe how to determine confidence intervals for the estimates of the various types of random frequency noise.
Frequency‐Domain Circuit Analysis
Authors: Biey Mario , Maio Ivan A.
Published: April 2005

By using suitable transformationsthat is, Laplace transform or Fourier transform the original integrodifferential equations, which are linear with constant coefficients, are reduced to algebraic equations, where the original time functions are substituted by complex‐valued functions of a complex variable ssjo in the case of Laplace transform, or simply jo in the case of Fourier transform. Then the system of linear algebraic equations is solved for the new transformed functions. Finally, an inverse transformation recovers the requested voltages or currents as functions of time. When following this procedure, the analysis is said to be performed in the frequency domain or, alternatively, in the s domain when an explicit reference to the Laplace transform is preferred.
Gallium Nitride for Electronics
Authors: Lee Jong-Wook , Adesida Ilesanmi
Published: April 2005

In addition to their usefulness in optoelectronic applications, GaN‐based devices also have excellent electronic properties such as high critical breakdown fields, high saturation velocity, and good thermal conductivity. Many laboratories around the world have demonstrated microwave power performance for GaN devices that are far superior to the performance of other solid‐state device technologies. The GaN‐based high‐electron‐mobility transistor (HEMT) is considered an ideal candidate for highpower and high‐temperature RF/microwave applications.
High‐Temperature Superconductors
Authors: Mansour Raafat R.
Published: April 2005

This article provides an overview of the microwave applications of high‐temperature superconductor (HTS) technology. The main characteristics of HTS materials are outlined, highlighting the differences between superconductors and normal conductors. The article also presents the most recent progress in the development of HTS filters, multiplexers, cryogenic receivers, delay lines, and antennas. A brief summary of cryocooler technology and cryopackaging requirements is presented. The benefits of using HTS technology in wireless and satellite systems are also discussed. Newcomers to the field are encouraged to continue reading about the subject to understand more about the potential challenges and limitations of this revolutionary technology.
IMPATT Diodes and Circuits
Authors: Mc Clymonds James W.
Published: April 2005

This article will explain the basic principles for designing IMPATT diode circuits, beginning with the characteristics of the diodes. General circuit principles will be discussed, and calculations of amplifier circuit performance will be illustrated. The general principles then will be applied to several types of single‐diode circuits. Last, an approach for building very high‐power transmitters with hundreds of diodes will be shown.
Integrated Circuits
Authors: Ranganathan N. , Venkataramana Raju D.
Published: April 2005

The field of integrated circuits is broad. The inert substrate processes, further divided as thin and thick film processes, yield devices with good resistive and temperature characteristics. However, they are used mostly in low‐volume circuits and in hybrid ICs. The two most popular active substrate materials are silicon and gallium arsenide (GaAs). The silicon processes can be separated into two classes: MOS (the basic device is a metal oxide semiconductor field effect transistor) and bipolar (the basic device is bipolar junction transistors).

The transistor–transistor logic (TTL) family of circuits constitutes the most popular type of bipolar and is still used in many high‐volume applications. The emitter‐coupled logic (ECL) devices are used for high‐speed parts that form the critical path delay of the circuit. The MOS family of processes consists of PMOS, NMOS, CMOS, and BiCMOS.
Magnetrons
Authors: Osepchuk John M. , Ruden Thomas E.
Published: April 2005

The magnetron has survived in an era when most electron tubes have been replaced by solid‐state devices in modern electronic systems.

A wide spectrum of related devices are being developed for specialized applications. These include crossed‐field amplifiers, voltage‐tuned magnetrons, beacon magnetrons, and relativistic magnetrons. Applications range from the classical radar through industrial heating to microwave weapons.

Future applications remain unpredictable, but many are being explored. Advances in computer modeling will eventually produce success.
Microstrip Transitions
Authors: Holzman Eric L.
Published: April 2005

Microstrip line is a printed microwave transmission line used to interconnect microwave devices on an electronic circuit board. Coaxial and waveguide transmission lines are used to interconnect different electronic circuit boards. Thus, transitions are often required between microstrip and other transmission lines. These transitions must have low loss and be well matched, be easy to fabricate and be mechanically robust. This article surveys many of the most commonly used microstrip transitions.
Low Noise Amplifiers
Authors: Nair Vijay
Published: April 2005

This article discusses the noise theory of silicon and GaAs devices and its application in microwave amplifiers. Discussions of small‐signal equivalent circuits, amplifier gain and stability criteria, gain, and noise figure circles are included. Narrowband and broadband amplifier design procedures and specific considerations are also explained. Low‐noise amplifier (LNA) design techniques and some LNA examples are also presented.
Microwave Circuits
Authors: Gupta K. C. , Cebi Haki , Cho Choonsik , Feng Zhiping
Published: April 2005

The term “microwave circuits” is used to identify the electrical circuits used at microwave frequencies for performing signal processing functions like amplification, frequency conversion, mixing, detection, phase shifting, filtering, and power dividing. By “microwave frequencies,” we refer to electromagnetic signals whose wavelength is in centimeters, roughly from 30 cm to 1 mm with the corresponding frequencies ranging from 1GHz (GHz=109 Hz) to 300 GHz. band. Microwave frequencies present several interesting and unusual features not found in other portions of the electromagnetic frequency spectrum. These features make microwaves uniquely suitable for several useful applications in telecommunications, radar, industrial heating and sensors, and so on. The most common consumer application of microwaves is the domestic microwave oven used for food processing.
Microwave Integrated Circuits
Authors: Das Nirod K. , Bolle Donald M.
Published: April 2005

In this article a general overview and basic principles of operation of a class of highly integrated analog devices and circuits, used for applications in the microwave and millimeter‐wave frequency range, are presented. Although there are subgroups of sister technologies that evolved over the years, having different acronyms such as MIC (microwave integrated circuits in hybrid form), MMIC (monolithic microwave integrated circuits), and MCMs (multichip modules), their basic principles of operation are similar, with their objectives and scopes rapidly overlapping. The discussions in this article may be directed to a broad class of such integrated circuits, referred to in general as microwave and millimeter‐wave integrated circuits, with “MMIC” as a generic acronym.
Microwave Limiters
Authors: Kaul Roger
Published: April 2005

A microwave limiter is designed to allow low‐power signals to pass through it, while attenuating high‐power signals. Stated another way, microwave limiters are powerdependent attenuators that prevent intense microwave energy from interfering with susceptible microwave components in the latter stages of a cascade.

Many microwave limiter technologies have been investigated since the midtwentieth century. The solid‐state limiter, which was first designed using the varactor diode, today employs the Si pin (or PIN) diode because of the pins lower capacitance per unit area resulting in better thermal characteristics, in addition to the fact that it requires no external power supply. Also a MESFET‐based, MMIC‐compatible microwave limiter is being developed for integration with the low‐noise amplifiers common in MMIC designs. Furthermore, although gaseous limiters are widely used in high‐power radars as receiver protectors, ferrite limiters have not found the same wide use.
Microwave Measurements
Authors: Ferrero Andrea , Teppati Valeria , Pisani Umberto
Published: April 2005

This contribution discusses microwave measurements principles and techniques. The first section describes power, spectral, and noise measurements. Section 2 discusses network analyzer measurements, calibrations, and time‐domain reflectrometry. Finally, some advanced measurement techniques, as load‐pull and time‐domain waveform characterization, are described.
Microwave Phase Shifters
Authors: White Joseph F.
Published: April 2005

This section treats the semiconductor phase shifter. While they could be built using a variety of semiconductors, diodes, and bipolar and field‐effect transistors, the principal development was with silicon pin diodes because of their relatively low cost, high microwave Q, and inherent inertia to changes in characteristics with applied microwave (RF) excitation.
Microwave Solid‐State Devices
Authors: Schreurs Dominique M. M.-P.
Published: April 2005

This article presents an overview of the solid‐state devices that are now being used in telecommunication systems. We discuss several families of microwave and millimeter‐wave diodes and transistors. For each device type, we briefly describe the physical operation, discuss the properties and frequency limitations, and outline the main application areas.
Military Communication
Authors: Wang Charles C. , Nguyen Tien M. , Goo Gary W.
Published: April 2005

In general, military communication systems are different from ordinary systems in various specific security requirements, namely, robustness in hostile environments, shielding from adversaries, and immunity from unfriendly eaves‐dropping. Hostile environments to communications are radiofrequency interference (RFI), spoofing, jamming, and fading, either natural or human‐made. In recent years, synthetic aperture radar (SAR) has been extensively utilized for remote sensing.
Millimeter‐Wave Integrated Circuits
Authors: Wang Huei , Lin Kun-You , Liu Ren-Chieh , Chang Hong-Yeh
Published: April 2005

Millimeter‐wave (MMW) components are becoming more available and affordable because of advances in design, processing, testing, and packaging technology. MMW circuits have become smaller, highly integrated, and low‐cost, and are being applied in instrumentation, electronic warfare, satellite communications and other applications. As a result, many MMW systems are being developed and deployed that provide new and unique capabilities such as more information transfer (wider bandwidth), enhanced precision (higher resolution), and all‐weather operation (through fog, dust, and smoke), for both military and commercial applications. Monolithic MMW integrated circuits (MMICs) are crucial to meet the requirements for the MMW systems and play an important role in the MMW components. This article describes the current status of MMW monolithic integrated circuits, including the MMIC technologies, representative designs, and performance for various integrated circuits.
Mixer Circuits
Authors: Kimura Katsuji
Published: April 2005

Mixers are used to shift the received signal to an intermediate frequency, where it can be amplified with good selectivity, high gain, and low noise, and finally demodulated in a receiver. Mixers have important applications in ordinary low‐frequency and microwave receivers, where they are used to shift signals to frequencies where they can be amplified and demodulated most efficiently. Mixers can also be used as phase detectors and in demodulators, and must perform these functions while adding minimal noise and distortion.
Mobile Radio Channels
Authors: Vaughan Rodney G.
Published: April 2005

In this article we describe the properties of a communications channel when one or both of the radio terminals is moving. Examples of such channels occur with vehicular terminals and cell phones. However, some properties of these channels also occur in links where some form of multipath occurs, such as point‐to‐point links, where there is also a ground bounce path; long‐range point‐to‐point links with atmospheric refractive paths; and non‐line‐of‐sight links, which rely on radiowave scattering for the propagation paths. The changing phase mix of the multipath causes signal fading and propagation paths. The changing phase mix of the multipath causes signal fading and Doppler shifts in the channel, and these conspire to degrade the quality and capacity of both analog and digital communications. The physical link characteristics and their effects on a digital link are described using tractible mathematical and statistical models.
Monolithic Microwave Integrated Circuits (MMICs)
Authors: Bahl Inder J.
Published: April 2005

Advanced military and microwave systems are demanding increased integration, reliability, radiation hardness, compact size, and lower cost when produced in large volume, whereas the microwave commercial market, including wireless communications, mandates low‐cost circuits. Monolithic microwave integrated circuit (MMIC) technology provides an economically viable approach to meeting these needs. This article deals with MMIC fabrication, substrates, matching networks, active devices, and monolithic design of microwave components and circuits, including device modeling and EM simulations. Typical monolithic microwave circuits and their performance, and MMIC packaging are also discussed.
Multibeam Antennas
Authors: Balling Peter
Published: April 2005

The article introduces multibeam antennas by reviewing a number of applications describing their importance for modern radar and communications systems. Simple aperture distributions and antenna sizing formulas for beamwidth and gain rolloff are discussed, and examples are provided on the implementation of both active and passive multibeam antennas using different beamforming technologies.

The problem of forming simultaneous multiple beams from a common aperture is investigated considering the Stein limits for passive antennas. The implementation of optimum beamforming networks is discussed. Both array antennas and array‐fed reflector antennas, including dual‐ and multimode antenna systems, are reviewed.

The design of multibeam reflector antenna systems is considered in detail. Scan aberrations and cross‐polarization effects of the signal‐offset reflector are quantified, describing means to improve the antenna performance. The potential of compensated dual‐offset reflectors, including front‐fed and side‐fed offset Cassegrain antennas for large scan angles, is demonstrated.
Multiple‐Access Schemes
Authors: Sidi Moshe
Published: April 2005

Multiple access schemes are natural not only in communication systems but also in many other systems such as computer systems, storage facilities, or servers of any kind, where resources are shared by a number of nodes. In this article we address mainly shared communication channels.

The goal of this article is to survey typical examples of multiple access schemes. These examples include TDMA, FDMA, Aloha, polling, and tree‐based schemes. The allocated space for the topic of multiple access schemes in the encyclopedia (which is yet another shared resource) is just too tiny to include all the ingenious multiple access schemes that have been designed by researchers over the years.
Noise Generators
Authors: Upadhyaya Shambhu J.
Published: April 2005

Noise has been studied extensively in the literature because noise reduction is one of the major goals. A more compelling reason for the study of noise is its potential application in real life. These applications encompass biomedical engineering, electronic circuits, communication systems, cryptography, computers, electro‐acoustics, geosciences, instrumentation, and reliability engineering. This article addresses the various noise generation techniques and implementing them in analog and digital circuit technology and concludes with a discussion of typical applications.
Noise, Hot Carrier Effects
Authors: Matulionis Arvydas
Published: April 2005

This article deals with electronic noise caused by electrons and holes in semiconductors. For simplicity, the term electrons will be used, unless mentioning holes is necessary for specific reasons.

Measuring noise out of equilibrium provides new information about kinetic processes in electron gas–new as compared with that available from the average values of observables. As a result, investigation of hot electron noise proves to be a powerful tool for diagnosing nonequilibrium states in semiconductors subjected to high electric fields. Moreover, the knowledge obtained of the microscopic origin of hot‐electron noise helps to control it and suggests how to eliminate some sources of excess noise through improvement of material technology and circuit design, thus contributing to development of highly sensitive low‐noise devices.
Noise, Low‐Frequency
Authors: Handel Peter H.
Published: April 2005

Low‐frequency noise, containing fluctuations of current or voltage with frequency components below 10 kHz, is mainly fundamental 1/fnoise and sometimes nonfundamental 1/fnoise. In addition, shot noise, generation–recombination (GR) noise, and thermal noise, which are important at higher frequencies, also extend to the low‐frequency domain. All theses forms of electronic noise, are characterized by the mean squared current fluctuation ((δI)2) [or ((δV)2≡RMSδV)2for voltage], measured in series with (or across) the device or sample under test, when a constant voltage (current) is applied, except for thermal noise, which is present even in thermal equilibrium, with no bias applied.
Nonlinear Circuit Design
Authors: Suárez Almudena
Published: April 2005

In this contribution, nonlinear synthesis techniques for microwave circuits are presented. Emphasis is made on their principles, implementation, and applications. Four main types of nonlinear circuit are considered: frequency mixers, oscillators, frequency dividers and frequency multipliers. The operation principles and their main characteristics are introduced, together with the most useful synthesis techniques. Approximate analytic techniques like Volterrra series and the describing funciton are presented, as well as design tools, based on harmonic balance, such as the auxiliary generator, for oscillator and frequency multipliers. Analyses of noise and stability are also carried out. The techniques are illustrated by means of simple but practical FET‐based circuits.
Notch Antennas
Authors: Lee Richard Q.
Published: April 2005

Notch antennas, also known as the tapered slot antennas (TSA), have been the topics of research for decades. TSA has demonstrated multioctave bandwidth, moderate gain (7–10 dB), and symmetricE‐ andH‐plane beam patterns and can be used for many different applications. This article summarizes the research activities on notch antennas over the since the early 1990s with emphasis on their most recent advances and applications. The article begins with some discussions on the design of single TSA, then follows with detailed discussions of issues associated with TSA designs and performance characteristics. To conclude the article, some recent developments in TSA arrays and their applications are highlighted.
Phase Noise and Measurements
Authors: Chang Heng-Chia
Published: April 2005

The phase of the electric signals or electromagnetic fields from the circuits and devices is often modulated or demodulated with important information in modern communication systems. However, there are always some random fluctuations in the phase of the signals. The termphase noiseis used to describe such short‐term random fluctuations of the signals. Those phase noise sources may come from the thermal noise (thermal motion of the carriers), shot noise (discrete properties of the electric current sources), or several other mechanisms inside the devices, circuits, or wired or wireless medium [1] The phase noise can affect the signal‐to‐noise ratio (SNR) and bit error rate (BER) of the received signals, and then the channel sensitivity, minimum detectable signal power, operating range, and selectivity in the communication systems. This article focuses on phase noise in the oscillators because most of the phase noise sources in the communication systems come from the oscillators. This article is divided into two main sections on phase noise theory and phase noise measurement techniques.

In Section 1 (on phase noise theory), the author describes the simplified oscillator model and its phase dynamics. The oscillator phase noise can be derived by using small‐signal fluctuations around the operating (carrier) frequency, where the fluctuations are caused by the intrinsic noise sources. The Fourier transform and Wiener–Khintchine theorem are applied to the phase noise expressions [2–8]. The relationship between the noise resistance/admittance of the oscillator and Leeson's model is also derived. In Section 2 (on phase noise measurement) several popular measurement techniques [9–13] are explained, including the spectrum analyzer, frequency discrimination, and double‐balanced mixer methods. The author also explains the advantages and disadvantages of these measurement techniques. The article concludes with some references for the interested readers to 10 independently study phase noise theory and related measurement techniques in further detail [1,14–18].
Photonic Bandgap (PBG)
Authors: Martínez Alejandro , Griol Amadeu , Sanchis Pablo , Martí Javier
Published: April 2005

Photonic bandgap materials are expected to play an important role in the near future mainly because of their potential capability to provide extremely compact optical circuits. A large variety of applications have been proposed and demonstrated in both the microwave and optical regimes. In this way, the microwave regime has become a useful instrument to experimentally demonstrate applications initially proposed for the optical domain, thanks to the scaling properties of the Maxwell equations and the easier and cheaper fabrication and testing capabilities of the fabricated structures compared to their optical counterparts. This can be illustrated by the fact that the first photonic bandgap structures were developed to work at microwave frequencies. Photonic bandgap structures have also attracted interest for microwave applications in themselves, and several proposals of electromagnetic bandgap techniques and circuits aimed at improving the properties of current microwave and millimeter‐wave devices have been reported.

The concept of photonic bandgap is so wide that it becomes unapproachable to summarize all the knowledge related to this field in a few pages. Thus, although a general vision of the field is offered to the reader, we have focused our efforts on passive microwave components and devices that make use of the principles of photonic bandgap.

We start this chapter with a brief historical introduction and a description of photonic bandgap fundamentals. Then, we first summarize some typical functionalities employed in passive optical devices (waveguides, directional couplers, Y junctions, and interferometers), which are tested at microwave frequencies by using a photonic bandgap structure based on alumina rods. The obtained results allow us to visualize a near‐future implementation of the proposed devices using photonic bandgap technology in the optical domain. In a second step, we show how the photonic bandgap concept can be applied to a very extended microwave technology, specifically microstrip technology, and describe and experimentally demonstrate some applications such as novel filter structures and harmonic suppression in microstrip bandpass filters based on coupled rings. Finally, a brief summary of the application of photonic bandgap structures in the optical regime is drawn.
Spatial and Quasi‐Optical Power Combining
Authors: Navarro Julio A.
Published: April 2005

Spatial and Quasi‐Optical Power Combining by Dr. Julio A. Navarro reviews the early history of radar and some critical microwave sources and components which have made the concept viable and successful since its conception. The contribution provides background to the field by referencing power combining review papers and spatial power combining textbooks. This work also references significant contributors to active antennas and power combining in the past decade. The article updates major improvements in the field since the mid‐1990s when the first textbook on the subject was written. The contribution lists key qualities and figures‐of‐merit to gauge the success of on‐going research and adequately compare its results with others in the field. These qualities are described along with methods for calculation to assist newcomers working in the field. Additional areas for research are briefly described to highlight some of the more recent off‐shoots of this field.
Q‐Factor
Authors: Kajfez Darko
Published: April 2005

Radiofrequency and microwave resonators are characterized by their resonant frequency, coupling coefficient, and unloadedQfactor. Definition of theQfactor consists of a ratio of the stored energy and the dissipated power at resonant frequency. The distinction should be made between the unloaded, loaded, and externalQ. The article provides some frequently used equations related to the application ofQfactors. The measurement techniques for determining theQfactor can be classified as being of transmission type, reflection type, and reaction type. The measurement is typically performed with a vector network analyzer and a curve‐fitting procedure is applied to determine the loaded resonant frequency, the loadedQ, and the coupling coefficient. The measurement is redundant as many more data points are taken then minimum necessary, so that it becomes possible to estimate the random uncertainty of the unloadedQ.
Quadrature Phase Shift Keying (QPSK)
Authors: Tatu Serioja O. , Bosisio Renato G.
Published: April 2005

Quadrature phase shift keying (QPSK) is a modulation technique used for sending data over radio or cable networks.

This article presents in details the QPSK principle, as well as modulators and demodulators using the conventional approach. A new concept to modulate or to demodulate a QPSK signal using the six‐port circuit at millimeter‐wave frequencies is also presented.

The coherent carrier recovery circuit for the demodulation of QPSK signals is an important aspect to be considered. Three regeneration schemes (Costas loop, multiplication loop, and reverse modulation loop) are presented.

The probability of error for QPSK in the presence of noise is derived using the equations of I‐ and Q‐demodulated signals.
Radar Antennas
Authors: Cui Tie Jun , Chew Weng Cho , Chen Fu-Chiarng
Published: April 2005

The radar antenna is an important component of radar. For different radar types, the requirement for antenna performances and functions is varied. Because the subject of radar antennas is very extensive, only selected types and performances of radar antennas are discussed in this article. Therefore, because of limited space, we discuss only reflector antennas and array antennas.
Radar Applications
Authors: Tsihrintzis George A.
Published: April 2005

Radar (radiodetection andranging) systems attempt to infer information about remotely located objects from reflections of deliberately generated electromagnetic waves at radio‐ and microwave frequencies. Typically, the information sought is detection of the presence of target objects in the midst of clutter, recognition (classification) of targets, and estimation of target parameters such as range distance from the radar antenna), bearing (azimuth and elevation), orientation, velocity, acceleration, or backscattering cross section (reflectivity) distribution. Today's radar systems perform these tasks for multiple targets simultaneously, at the finest possible target resolution and with the highest possible accuracy. Additionally, the domain of utilization of radar techniques has expanded beyond the traditional aircraft detection and ranging application. Indeed, modern radar applications include search, tracking, and navigation radar for spread targets, high‐resolution aerial imaging radar, weather observation radar, and ground‐ and foliage‐penetrating radar. To achieve their expanded tasks, modern radar systems combine high‐quality hardware with sophisticated signal design and processing algorithm development and implementation based on statistical descriptions of both the target characteristics and the clutter distributions.
Radar Imaging
Authors: Chen Victor C.
Published: April 2005

Radar imaging is an imaging method obtained by processing radar signals reflected from an object and generating an image of that object. The purpose of this article is to introduce basic concepts of radar imaging, including radar imaging geometry, synthetic aperture, stripmap mode, spotlight mode, and inverse mode. This article summarizes algorithms for radar imaging, including the range–Doppler algorithm, range migration algorithm, chirp‐scale algorithm, polar formatting algorithm, phase gradient algorithm, prominent point processing algorithm, and time–frequency‐based image formation algorithm. Issues in radar imaging of moving targets are also introduced.
Radar Polarimetry
Authors: Sletten Mark A. , Mc Laughlin David J.
Published: April 2005

This article summarizes the fundamentals of radar polarimetry and gives examples of related applications and research. The mathematical foundation is described first. This discussion includes explanations of the various ways in which polarized and partially polarized electromagnetic waves can be described and how formalisms are used to express the polarimetric scattering properties of objects and surfaces. The scattering, Mueller, covariance, and coherency matrices embody these formalisms. Some practical aspects of polarimetric radar design are then discussed, and the article concludes by summarizing applications of polarimetry and areas of active research, including scattering studies, image classification, contrast enhancement, meteorology, and topographic mapping.
Radio‐Frequency Identification Systems (RFID)
Authors: Hayashi Hitoshi
Published: April 2005

Radiofrequency identification system (RFIDs) can provide an automatic means of collecting identification data for people, animals, and objects. Furthermore, with the advent of Internet systems, RFID systems are expected to further expand into new ubiquitous applications. In this article, we present a brief introduction to RFID systems.
Radio‐Frequency Integrated Circuits
Authors: Chongcheawchamnan M. , Karacaoglu U. , Robertson I.D.
Published: April 2005

Silicon RFIC technology has become dominant for mobile and wireless applications in the low gigahertz range, and with heterojunction devices, the circuits are moving into the millimeter‐wave range. This article provides a summary of the technology, design, and application of RFICs.

The article includes sections on devices, passive components, CAD, amplifier design, oscillators, mixers, filters, and transceivers. It presents an overview of each topic, to give an up‐to‐date background in each topic.

A substantial part of the article is on modern aspects such as realizing high‐Qinductors, high‐efficiency power amplifiers, frequency synthesis, and direct conversion transceivers architectures. It finishes by describing the importance of considering the package integration as an important part of the design and the system‐in‐package concept.
Microwave and Radio Frequency Multipliers
Authors: Thomas D.G. , Branner G.R. , Kumar B.P.
Published: April 2005

Microwaved RF frequency multipliers are electronic devices that generate signals having frequencies that are integral multipliers of their input signal frequencies. These devices have applications in electronic instruments, radar, electronic warfare, and communication systems. This article covers theory and design of these devices that operate from the megahertz to millimeter‐wave regions. Detailed discussions of both passive and active realizations are included along with state‐of‐the‐art practical design examples. Over 170 references covering the current multiplier technology in RF and microwave bands are included.
Radio on Fiber Systems (RoF Systems)
Authors: Komaki Shozo , Tsukamoto Katsutoshi
Published: April 2005

The radio‐on‐fiber (RoF) system involves the synergetic use of emerging wireless and photonic technologies and has advantages of both wide‐area radio access capability and the low‐loss long‐hop transmission capability of optical fibers simultaneously. Since the RoF system directly converts the RF signal to an optical signal, this system provides universal network solutions that are independent of frequency band and air interface types. In this section, the basic configurations of the RoF system, devices, performance, and present and future applications of networking have been described.
Radiotelemetry
Authors: Tsou Haiping , Cheung Kar-ming
Published: April 2005

Radiotelemetry, by definition, is the science and technology of automatically measuring and transmitting data by radio from remote sources, as from space vehicles, to receiving stations for recording and analysis. It involves preparing of data generated at remote sources, transmitting data through radio channels, and processing data at the receiving stations. Behind these three tasks, how to convey the information in a reliable and timely manner through a communication link is the most fundamental problem in this field.
Rough Surface Scattering: Numerical Simulations and Applications in Microwave Remote Sensing
Authors: Li Qin , Xia Ming Yao , Tsang Leung , Zhou Lin , Chan Chi Hou , Li Zhong Xin
Published: April 2005

In this article we present rough‐surface bistatic scattering and emission based on NMM3D (numerical Maxwell model using 3D simulations). Results are computed using the method of sparse matrix canonical grid with RWG (Rao–Wilton–Glisson) basis functions. Results are illustrated for active and passive microwave remote sensing of soil moisture and ocean. We also describe recent numerical simulation techniques of the single integral equation and the multilevel UV method in rough surface scattering.
Satellite Antennas
Authors: Dybdal R. B.
Published: April 2005

Satellite antenna development is a significant part of present‐day antenna technology. Much progress in antenna systems for both the space and user segments has been made. However, future requirements such as the development of satellite systems for personal use provide a rich opportunity for further development and challenges to meet the increased performance levels demanded in future systems and applications.
Schottky Barrier Diodes and Their Applications
Authors: Davis W. Alan
Published: April 2005

Although times have changed, the Schottky barrier diode remains an important component in many systems because of its unique features.

The discussion will first focus on the origin of the energy bands and their relationship to the Fermi level. The simple theory is later modified by the barrier‐lowering effect and the presence of surface states. The reverse bias depletion capacitance and, subsequently, the forward current characteristics are determined. Equivalent circuit models are discussed that are useful for circuit design. Finally, some comments are made about recent progress in wide bandgap Schottky barrier diodes. The applications sections emphasize mixer design, as this seems to be the predominant use of Schottky devices.
SiC Device Technologies
Authors: Östling M. , Koo S.-M. , Domeij M. , Danielsson E. , Zetterling C.-M.
Published: April 2005

Silicon carbide (SiC) devices have drawn considerable attention for use in various applications due to the interesting materials properties of SiC. Commercial products are now available for high‐voltage and high‐frequency applications. Prototype devices show promising performance, whereas materials issues are still a hinder for economically viable production of large‐area devices with high yield. This article reviews the more recent progress in SiC devices and process technology and presents the state‐of‐the‐art SiC devices as well as new application areas such as ferroelectric field‐effect transistors (FeFETs).
Slotline Components
Authors: Fan Lu , Chang Kai
Published: April 2005

This article first discusses the fundamental slotline elements such as various T junctions, resonators, and transitions. After these general topics, several kinds of passive slotline integrated circuits are presented through a discussion of filters, hybrid couplers, and nonreciprocal devices. Finally, the applications of slotline to solid‐state integrated circuits, that is, mixers, oscillators, modulators, and frequency doublers, are described. These applications are supported by real circuit demonstrations and actual circuit performances. The implementation of solid‐state devices for the tuning and switching of resonances is also discussed.
Smart Materials
Authors: Awadelkarim Osama O. , Suliman Samia A.
Published: April 2005

In this article, we give the reader a brief introduction to a selected number of smart materials and structures. These materials include semiconductors and related structures, superconductors, piezoelectric materials, and shape memory materials. These materials are discussed in terms of their electrical, mechanical, optical, and chemical properties and possible engineering applications in the fields of nanoelectronics, nano/microelectromechanical systems, optoelectronics, and communication.
Standing Wave Meters and Network Analyzers
Authors: Schiek Burkhard , Gronefeld Andreas
Published: April 2005

This article will present a number of measurement systems for the determination of reflection coefficients (one‐port network analyzer or reflectometer) and for full characterization of two‐port networks. Although the concept ofS‐parameters is easily extended toN‐ports, measurement of networks with more than two ports will not be covered, because most commercially available hardware is built for two‐port measurements and can be used to characterizeN‐ports by simply terminating the unused N‐2 ports inZ0.
III–V Semiconductors
Authors: Snowden Christopher M.
Published: April 2005

This article provides a broad introduction to III–V semiconductors as a background to device and circuit technologies that use these materials. The reader is introduced to theoretical and practical concepts for this range of alloy semiconductors. The physical and chemical properties and behavior of these materials are discussed. Methods of growing epitaxial layers and fabricating microwave and RF devices are presented. A brief summary of the microwave applications of III–V semiconductors is included together with an overview of the state‐of‐the‐art performance.
Target Tracking
Authors: Drummond Oliver E.
Published: April 2005

Target tracking design and development is challenging if the measurement density is not sparse. Close targets, clutter , or false signal can cause conditions of dense measurements. The tracking algorithms used for a system need to be selected based on the specifics of the application. This article addresses alternative algorithms for both single and multiple target tracking; tracking using either a single sensor or data from multiple sensors (sensor data fusion); and discusses trade‐offs considerations for selecting appropriate algorithms for a system.
Volterra Modeling in Analog, RF and Microwave Engineering
Authors: Steer Michael B. , Gharaibeh Khaled M.
Published: April 2005

Volterra techniques are used in radiofrequency (RF) and Microwave engineering primarily in modeling the inputoutput characteristics of nonlinear circuits and systems that operate with limited bandwidth signals. Volterra models capture frequency‐dependent effects within the band. Two forms of the Volterra model exist; one being in the time‐domain invoking Volterra kernels in what is in effect a multidimensional convolution; and the other being a frequency‐domain form with what are called Volterra nonlinear transfer function akin to the transfer functions of linear circuits but, of course, extended to handle nonlinearities.
Waveguide Directional Couplers
Authors: Levy Ralph
Published: April 2005

Waveguide directional couplers are widely used as power monitors in microwave systems and test equipment. An even more important set of applications makes use of the 90° phase difference between the output signals, making them ideal for antenna feed networks, and as hybrid junctions or couplers for applications in balanced mixers, duplexers, and balanced amplifiers. Their common basic properties are outlined, and the design of the most common and useful types are described, namely, multiaperture and cross‐guide couplers, sidewall and topwall hybrids, and branch‐guide couplers. Modern design techniques based on exact synthesis are emphasized.
Waveguide Oscillators
Authors: Holzman Eric L.
Published: April 2005

Waveguide oscillators are DC‐to‐RF converters most commonly used as millimeter‐wave sources. This article describes the fundamentals of solid‐state, two‐terminal device oscillators employing waveguide circuits as resonators. Single‐device oscillators, varactor‐controlled oscillators, and waveguide resonant cavity combiners are overviewed.
Printed Inductors
Authors: Ooi Ban-Leong , Xu Dao-Xian
Published: April 2005

A new efficient method for calculating the inductance value of a spiral inductor with special emphasis on the nonuniform current distribution on the metallic trace is described. Based on the partial inductance method, a unified approach for modeling the eddy current and skin depth of spiral inductor has been presented. Our proposed method is validated with experimental results, and good agreement has been obtained.
Terahertz Science, Engineering and Systems—from Space to Earth Applications
Authors: De Maagt Peter , Bolivar Peter Haring , Mann Chris
Published: April 2005

The terahertz (THz) part of the electromagnetic spectrum falls between the lower frequency millimetre wave region and, at higher frequencies, the far‐infrared region. As the THz region separates the more established domains of microwaves and optics, a typical THz technique will incorporate aspects of both realms, and may even draw on the best of both. The two bounding parts of the spectrum also yield distinct sets of methods of generating and detecting THz waves. As a result of breakthroughs in technology, the THz region is finally finding applications outside its traditional heartlands of remote sensing and radio astronomy. Extensive research has identified many attractive uses and has paved the technological path towards flexible and accessible THz systems. This paper discusses the range of THz applications (both space and terrestrial) and will present the components and systems that are utilised for the region, both from a sort of historic perspective and from the point of view of recent developments. A split has been made in microwave THz and optical THz technology according to the underlying basic technologies. Future trends are also discussed.
Gratings and Grating Antennas
Authors: Rodenbeck Christopher T. , Chang Kai
Published: April 2005

Agratingis an array of parallel obstructions separated from one another at a distance comparable to a wavelength. When an electromagnetic wave is incident up on a grating, it scatters to one or more specific angles determined by the spacing of the grating and the frequency of the wave. Since this effect is a diffraction phenomenon, gratings are often also referred to asdiffraction gratings.

One of the most important uses of the diffraction grating is as an antenna for millimeter‐wave through optical frequencies. This type of diffraction grating is the primary focus of this article. In integrated optics, grating antennas are used to couple power into and out of dielectric waveguides. For millimeter‐wave systems, grating antennas have received attention for several key advantages that they have in comparison with other conventional microwave antennas. They have low radiation losses, they are inexpensive and easy to fabricate, and they are planar. There is also considerable interest in using grating antennas to implement low‐cost beam steering at millimeter‐wave frequencies.

This article examines gratings and grating antennas in a series of five sections. Each of these sections is presented in such a way that it may be read independently from the others. An overview of the historical development of diffraction gratings is presented. The fundamental principles behind grating diffraction are explained in a manner suitable for those with an RF/microwave background. A clear design procedure for grating antennas is offered, along with an extensive reference list for those interested in further study. Some of the latest and most impressive applications of millimeter‐wave gratings are described. The article then concludes with a brief discussion of the future of this field.
Microwave Resonance Plasma Source
Authors: Taube Alexander L. , Demyashev Gregory M.
Published: April 2005

This article summarizes important aspects of a microwave resonance plasma source (MRPS ) based on the resonance phenomenon and running at atmospheric pressure. The novel MRPS using the high‐efficiency tunable cylindrical resonant cavity of TM013mode and operating at 2.45 GHz, was designed and manufactured. The MRPS was successfully approved with different carrier gases (N2, Ar, He) and precursor (gases, liquids, and powders) for creation of thermal plasma torch.

Some examples of technological applications are highlighted. The feasibility of using the MRPS for nitriding/oxinitriding of Ti, 304 and 316 stainless steel, and 5140 steel by pure N2and with air (the mixture of N278 vol% +O221 vol%) was confirmed. For the purpose of plasma chemistry applications, two gaseous systems were chosen. The first one is CO2–H2O–N2, which imitates exhaust/flue gases. The second one is CO2–N2, which is of interest for deposition of superhard nanocrystalline carbon nitride (C3N4), the hardness of which is comparable to that of diamond. The MRPS commercially applicable in industry is practical for plasma chemistry, materials processing, coating deposition, surface treatment, and other applications.
Electromagnetic Field Computation in Planar Multilayers
Authors: Michalski Krzysztof Arkadiusz
Published: April 2005

The computation of electromagnetic fields in planar, multilayered, uniaxial media is discussed. In particular, a complete set of electric and magnetic dyadic Green functions is derived for such media, in a computationally efficient and convenient‐to‐use form, based on a transmission‐line equivalent circuit along the axis normal to the stratification.
Load‐Pull Techniques
Authors: Teppati Valeria , Ferrero Andrea , Pisani Umberto , Colantonio Paolo , Giannini Franco , Limiti Ernesto
Published: April 2005

This contribution is an overview on classic and advanced load‐pull measurement techniques. The definition of the main measured quantities along with the detailed description of several modern test sets will be given. Furthermore, several experimental results are reported to highlight the applicability and utility of these techniques for modern device development.