bluuebunny/crossref_metadata_2025_split huggingface dataset:
Digital Microwave Receivers
Authors: Luy Johann F. , Mueller TH. 
Published: April 2005

AbstractReducing complexity in RF systems is a challenge. Research for new broadband and multistandard antennas, high‐frequency bus concepts, and software‐configurable hardware platforms in order to fulfill the needs caused by an increasing number of communication and navigation standards are ongoing tasks.The high‐speed building blocks of software‐configurable digital receivers are composed of lowpass or bandpass filters, sampling and analog‐to‐digital converter (ADC) circuits, and decimator functions that convert the high‐speed sampling rates into lower rates and higher resolution, respectively. The specific design of receiver hardware architecture is a compromise between the specifications of the services to be handled by the receiver and the availability of components.The concept of bandpass‐limited subsampling (i.e., where the sampling frequency is lower than the carrier frequency) has become a very appropriate architectural approach as increasing cutoff frequency and speed of semiconductor technologies can be traded against resolution in this concept.Direct sampling poses high requirements for the analog‐to‐digital converter (ADC). The requirements are reduced significantly if a six‐port digital receiver architecture is used. The functional principle of six‐port devices is based on the measurement of four independent output powers corresponding to the complex ratio between two superposed electromagnetic waves under different phase angles. The six‐port architecture can work under broadband conditions but may be disadvantageous compared to direct‐sampling receivers with respect to their dynamic properties.Antialiasing filters are necessary components in ADCs. Three‐dimensional micromachined filter structures can provide high quality factors and low insertion losses at microwave and millimeter‐wave frequencies. Transimpedance amplifiers for a bandpass‐limited subsampling approach and limiting amplifiers can be designed and realized in commercial SiGe technology. The sampling circuit itself may use high‐speed Schottky diodes. Using these technologies, digital receivers are now approaching the millimeter‐wave range.
Digital Radio
Authors: Aalo Valentine A. 
Published: April 2005

Abstract
This article presents an overview of digital radiocommunications with emphasis on wireless personal communications.
The main objective of wireless personal communication is to allow the user access to the capabilities of the global network at any time and without regards to location and mobility.
Digital radio, used extensively in second‐generation and the evolving third‐generation systems, considerably improves the quality of the cellular system and enhances the services available to the mobile subscribers.
A/D and D/A Conversion Architectures and Techniques
Authors: Sonkusale Sameer , Zourntos Takis 
Published: April 2005

AbstractThis article is concerned with the data conversion subsystem that interfaces the front‐end and back‐end portions of the transceiver core. A data converter translates signals between analog and digital representations. Our emphasis is on data converters for mobile communication systems in which cost and power savings are a priority. Therefore, although much of our discussion is of a general nature, our presentation is geared toward CMOS integrated circuit implementation and applications with low to moderate bandwidths (e.g., communications with WCDMA, IEEE 802.11a/b, or Bluetooth protocols).
Diodes
Authors: Misiakos Konstantinos 
Published: April 2005

Abstract
In electronics terminology, diode refers to a two‐terminal device that allows current to flow in one direction while it blocks the flow of current in the opposite direction. Such devices usually employ semiconductor junctions or metalsemiconductor junctions. There are also diodes made of vacuum tubes or metalpurely ionic crystal contacts. This article deals with semiconductor p‐n‐junction diodes because they are the most widely used in practice because of their versatility, reproducibility, stability, and compatibility with integrated circuit technology.
Directive antennas
Authors: Alexeff Igor , Rader Mark , Kang Weng Lock 
Published: April 2005

AbstractRadio antennas that are directive have many advantages over stationary antennas. They can observe in one direction while ignoring much larger signals coming in from the sides. In addition, as transmitting antennas, they can direct a small amount of radiation directly to the proper receiver. Conventional directive antennas use large mirrors for short waves, such as are used in radar. For longerwave antennas, they use reflector and director elements aligned with the antenna. The basic problem with such arrays is that they are mechanically steered, which is slow and difficult to do with large antennas, especially in the presence of wind, ice, or snow.
Distributed Amplifiers
Authors: Koryu Ishii T. 
Published: April 2005

AbstractThe objective of this article is to present various aspects of distributed amplifiers. Distributed amplifiers are by definition, electronic amplifiers consisting of distributed circuit parameters. However, in practice, amplifier systems that consist of a number of discrete amplifiers associated with distributed parameter circuits are often termed distributed amplifiers; this latter amplifier is actually a pseudodistributed amplifier.
Electromagnetic Compatibility
Authors: Paul Clayton R. 
Published: April 2005

Abstract
This article includes general discussion of the subject of designing electronic systems to render them electromagnetically compatible with their environment, to ensure that, they (1) will not cause interference with other electronic systems, (2) be interfered with by other electronic systems, and (3) interfere with themselves. The discussions cover digital signal spectra, nonideal behavior of components, conducted emissions, radiated emissions, crosstalk, and shielding. The subject of governmental regulations is also discussed.
Electromagnetic Materials
Authors: Choudhury P. K. , Singh O. N. 
Published: April 2005

AbstractThis article describes the electromagnetic properties of the medium or material in which the process of electromagnetics takes place. The introductory part discusses the evolution of electromagnetics based on theories and experiments by the pioneering scientists. The following portions of the article deal with the different types of materials, including isotropic dielectrics, conductors, semiconductors, superconductors, anisotropic dielectrics, and electrooptic materials. The fundamentals of magnetic materials are described in slightly greater detail, explaining the mechanisms of magnetization and special materials such as ferrites. Bianisotropic materials and their constitutive equations are also discussed. Here the focus is on some of the fundamental aspects of the constitutive characterization of bianisotropic media. The last two sections describe the basics and important applications of the phenomena of magnetostriction and piezoelectricity.
Electromagnetic Shielding
Authors: Celozzi Salvatore , Araneo Rodolfo 
Published: April 2005

AbstractElectromagnetic shielding is an important constraint in the design of RF and microwave devices consisting in the mitigation of the emission levels of electromagnetic (EM) sources and/or in the protection of people or electrical and electronics apparatus and systems against possible effects due to external EM fields. Very often the need for electromagnetic shielding depends not only on functioning motivations but also on the compliance with standards fixing the limits of emission or immunity for various classes of apparatus and systems. Shielding theory, including analytical formulations, has been well developed in order to obtain guidance in practical problems and to firmly grasp the key factors on which the theory of electromagnetic shielding is based. For the difficulty in handling real configurations by means of exact analytical expressions, approximate formulations have been developed and improved over the years, while the analysis of the shielding effectiveness of closed structures, often referred to as enclosures, is generally performed in either the frequency or time domain, by using numerical techniques.
Electromagnetic Subsurface Remote Sensing
Authors: Chen S. Y. , Chew W. C. 
Published: April 2005

AbstractSubsurface electromagnetic (EM) methods are applied to obtain underground information that is not available from surface observations. Subsurface EM methods include a variety of techniques depending on the application, surveying method, system, and interpretation procedure, and thus a “best” method simply does not exist. One of the most challenging parts of subsurface EM methods is interpretation of the data. Data interpretation is also a critical factor in evaluating the effectiveness of the system. In the following sections, we will use several typical applications to outline the basic principles of subsurface EM methods. Physical insight is emphasized rather than rigorous mathematical analysis.
Electromagnetics, Time‐Domain
Authors: Bushyager Nathan A. , Tentzeris Manos M. 
Published: April 2005

AbstractIn this article, various time‐domain electromagnetic simulation methods, including the finite‐difference time‐domain (FDTD), transmission‐line matrix (TLM), finite‐element time‐domain (FETD), and multiresolution time‐domain (MRTD) techniques are discussed in detail along with grid optimization approaches. In addition, conformal meshing techniques, specifically finite‐volume time‐domain (FVTD) and generalized Yee FDTD methods are briefly descirbed. Also included is a discussion of code parallelization, grid excitation, absorbing boundary conditions, antenna modeling, and methods that can be used to deriveSparameters from time‐domain output data.
Electronic Warfare
Authors: Spezio Anthony E. , Duckworth Alan N. , Klemm Francis J. , Moroz Stanley A. , Talley James M. 
Published: April 2005

Abstract
Electronic warfare (EW) is the systems discipline that exploits an adversary's use of the electromagnetic spectrum to overcome threats that use communications, navigation, and radar systems. This article includes a description of the EW timeline and the various phases of conflict. Also provided is a summary description of the signal environment in which EW systems operate.
This article includes a description of the EW timeline and the various phases of conflict. Also provided is a summary description of the signal environment in which EW systems operate.
Fabry–Perot Resonators
Authors: Sauleau Ronan 
Published: April 2005

AbstractThe characteristics and the main applications of Fabry–Perot (FP) resonators are described at microwave frequencies, referring to a well‐documented state of the art.This article is organized in three sections. In the first, we present the basic properties of plane‐parallel FP interferometers using the traditional ray approach. Their performance is defined mainly in terms of power reflectivity of both partially transparent mirrors. Nevertheless many microwave and millimeter‐wave FP cavities employ metallic strip gratings or meshes as reflecting parts. The impact of the dispersive characteristics of these mirrors is investigated in details in Section 2. For that purpose, we first study the scattering parameters of inductive and capacitive meshes using transmission‐line models and compare them to rigorous numerical results. Then we analyze the influence of the grid geometries on the performance of plane‐parallel FP cavities (frequency responses, resonant frequencies, half‐power bandwidth, and insertion loss). Finally design rules and multilayer FP structures with metallic or dielectric mirrors are briefly considered. Various applications are discussed in Section 3: (1) frequency filters and diplexers, (2) directive antennas and multibeam and frequency beam scanning antennas, (3) open resonators with spherical mirrors for dielectric measurement, and (4) quasioptical power combiners and oscillators.
Signal Fading in Radio Communications
Authors: Janaswamy Ramakrishna 
Published: April 2005

Abstract
In this article we describe the causes of signal fluctuation in wireless systems and describe the phenomena of short‐term and long‐term fading. Some of the topics included are narrowband and wideband fading, Rayleigh fading, Ricean fading, lognormal fading, level crossing rates, average fade duration, channel coherence time, Doppler spread, delay spread, and coherence bandwidth. The impact of fading on the performance of systems and in the design of cell size is discussed.
Feedback Amplifiers
Authors: Schubert Thomas F. 
Published: April 2005

AbstractThis article considers the benefits of negative feedback on amplifier design: stabilization of gain, reduction of nonlinear distortion, increased bandwidth, and selective modification of input and output resistance. Basic definitions are followed by a general discussion of the properties of a feedback system. Amplifiers are divided into four categories of feedback topology, and the specific properties of each topological type are determined. The drawbacks of feedback, reduction of gain, and the possibility of oscillation are also considered. Several compensation methods to improve amplifier stability are discussed.
Filter Synthesis
Authors: Lueder Ernst 
Published: April 2005

AbstractThe most common types of components for classical filters are lossless inductors and capacitors, as well as ideal transformers for the two‐port and resistances R1 and R2 as internal resistance of the source and as the terminating load. This case is treated in this article. Other types of components are switches such as FETs, capacitors, and operational amplifiers in so‐called switched capacitor filters or delays, adders and multipliers in digital filters or resistors, capacitors and operational amplifiers in RC‐active filters, or electromechanical transducers and a set of electrodes in surface acoustic wave (SAW) filters, which are treated in the last section.Guidelines will be presented on how to determine from filter tables the component values of a filter meeting given specifications. This should enable a system engineer to achieve a quick filter design by selecting the appropriate type of filter and by then finding the component values in a table.
Finline Components
Authors: Menzel Wolfgang S. 
Published: April 2005

AbstractFinline is a planar transmission line suspended in theEplane of a metal waveguide. The electromagnetic field is guided by a slot in the finline metallization. This contribution gives an overview of the possibilities of realizing passive as well as active components based on this type of transmission line. The article begins with a discussion of filters, directional couplers, and antennas and nonreciprocal components are mentioned later. It continues with a discussion of diode‐based components such as detectors, p‐i‐n diode attenuators or switches, mixers, and phase shifters. After a short remark on oscillators and amplifiers, a number of integrated components and front ends are presented.
Frequency‐Division Multiplexers
Authors: Snyder Richard V. 
Published: April 2005

AbstractFrequency‐division multiplexers are networks used either to split an input spectrum into possibly, but not necessarily, contiguous subportions, or alternatively to combine discrete spectral inputs into a common output. Designers and theoreticians have traditionally treated the design methodology as “black art,” and it has been difficult to formally learn “how to multiplex.” This article presents some of the many multiplexing techniques that have been developed since the early 1950s, and provides a good starting point for would‐be multiplexer designers.
Frequency Independent Antennas
Authors: Filipovic Dejan S. , Cencich Thomas P. , Nurnberger Michael W. 
Published: April 2005

AbstractFrequency‐independent (FI) antennas are radiating structures capable of maintaining consistent impedance and pattern characteristics over multiple‐decade bandwidths. Their finite size limits the lowest frequency of operation, and the finite precision of the center region bounds the highest frequency of operation. The geometry of a frequency‐independent antenna must be specified by angles alone, and principles such as truncation and self‐complementarity are necessary and desired, respectively. In this article, Rumsey's theory of FI antennas, developed in the mid‐1950s, is thoroughly discussed, and historical highlights listing the most important contributions in this area are given. A mathematical derivation for a general FI structure is provided, and some special cases are considered both theoretically and practically. A description and an explanation of the underlying theory of operation for several FI antenna types, including equiangular spirals, conventional and unconventional sinuous antennas, and log‐periodic folded slot arrays, are also provided. A view of frequency independence through the modal content and contamination of the radiated far field is emphasized. Considerations for flush/conformal mounting are briefly discussed, including the use of log‐periodic lossless cavities and broadband conical cavities.
Galerkin Method (Rayleigh–Ritz Method)
Authors: Weile Daniel S. , Wildman Raymond A. , Pisharody Greeshma , Mohan Anuraag 
Published: April 2005

Abstract
Galerkin's method and the Rayleigh–Ritz method form the mathematical underpinnings of many modern computational techniques for the solution of electromagnetics problems. In this work, the history of these two methods is reviewed, and each of the methods is described in detail. The relationship between the methods is explored, as is their relationship with the modern finite‐element method and method of moments. Numerical examples of the methods are provided to clarify the exposition.
Gallium Arsenide Technology and Applications
Authors: Manes G. F. 
Published: April 2005

AbstractStarting from the early 1970s, the increasing request for solid‐state devices operating at microwave frequencies lead to investigations of semiconductor structures as alternatives to silicon.Among various solutions, gallium arsenide generated interest and eventually emerged as the favorite material for high‐frequency applications due to the high carrier mobility compared with silicon devices.The advantages in speed and high‐frequency performance of GaAs are slightly offset by the manufacturing process limitations of GaAs, in terms of both complexity and reproducibility as opposed to Si.GaAs devices find application at RF and microwave frequencies for both linear and high‐speed logic applications.GaAs microwave devices find extensive use in consumer applications as well in sophisticated warfare electronics. GaAs devices are used in the form of discrete components or microwave monolithic integrated circuits (MMICs). GaAs also exhibits relevant optical properties and finds extensive applications in optoelectronics, including LEDs, laser diodes, and solar cells.
Uniform Geometrical Theory of Diffraction
Authors: Pathak Prabhakar H. 
Published: April 2005

Abstract
Keller's geometrical theory of diffraction (GTD) [1,2] constitutes a major breakthrough for solving problems of electromagnetic (EM) radiation and scattering at high frequencies. The GTD can also be applied to solving acoustic and elastic wave problems; however, only the EM case is discussed here.
Recently, the development of fast solvers for signifi‐cantly increasing the efficiency of numerical methods in solving large problems has met with some success. However, for truly large problems, asymptotic high‐frequency methods in general, and especially ray methods such as the GTD and its uniform version, still remain the most useful analysis tools.
Ge‐Si Alloys and Devices
Authors: Russer Peter , Luy Johann-Friedrich 
Published: April 2005

AbstractThe silicon–germanium heterojunction bipolar transistor enabled the breakthrough of siliconbased MMIC (monolithic millimeter‐wave integrated circuit) technology [1,6]. Amplifiers and tunable oscillators or with maximum operation frequencies beyond 80GHz become feasible.Silicon as a substrate for millimeter‐wave monolithically integrated circuits was suggested in 1981 by RCA [22]. Since 1986 in the field of silicon monolithic millimeter‐wave integrated circuits (SIMMWICs) there have been research activities at the former AEG‐Telefunken Research Institute (now DaimlerChrysler Research Center) and at the Technische Universitat¨ München [23–29].Monolithic integrated millimeterwave circuits based on silicon and SiGe will give new options for millimeter‐wave sensor and communication applications.
Gyrators
Authors: Frey Douglas R. 
Published: April 2005

AbstractAgyratoris a nonreciprocal electrical network. It is capable of transforming signals or energy represented in terms of one electrical quantity, such as voltage or magnetic field, to another electrical quantity that may be of similar type or of a complementary type, such as current or electric field. Such networks are quite useful in electronic systems, since one often wishes to design systems with a limited set of component types or with restrictions regarding certain physical parameters.
Gyrotrons
Authors: Ives R. Lawrence 
Published: April 2005

AbstractGyrotrons and gyroamplifiers produce high levels of RF power between 20 and 200 GHz. Power levels range from a few kilowatts to more than 1 MW of continuous or pulsed power. Because these devices use overmoded RF circuits, they are not subject to size limitation imposed by most linear beam, vacuum, or RF sources. Consequently, high levels of RF power can be produced while avoiding excessive thermal loading from RF losses on the device structures. Gyrotrons are most commonly used to heat plasmas in fusion devices, such as tokamaks and stellerators. Other applications, such as ceramic sintering, microwave chemistry, and RF sources for accelerators and colliders, are also being explored. Gyroamplifiers are being developed for high‐power radar at frequencies above 30 GHz. Research is continuing to increase the output power of both oscillators and amplifiers.
Hankel Transforms
Authors: Rahman M. 
Published: April 2005

AbstractThe object of this article is to introduce integral transform of a particular type, called theHankel transform, and to illustrate theuseof this method by means of examples. The treatment is that of a review article and as such is not meant to be exhaustive; its aim is to give a concatenated account of known results rather than present new ones. The emphasis throughout is on those results that are of frequent occurrence in boundary value problems of mathematical physics, but some indication is also given for possible theoretical investigations.
Harmonics Oscillators, Circuits
Authors: Linares‐Barranco Bernabé , Rodríguez‐Vázquez Ángel 
Published: April 2005

Abstract
In electronics a harmonic oscillator is an electronic circuit that generates a sinusoidal signal. This signal can either be a voltage, a current, or both. Harmonic oscillators are not restricted to electronics. They can be found in many other disciplines. However, they always can be described by similar mathematical equations. A very familiar harmonic oscillator is the harmonic pendulum, which is found in many high‐school physics textbooks.