bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low‐Pass Filters
Authors: Choi Chiu H. 
Published: April 2005

Abstract
A lowpass filter suppresses the high‐frequency components of a signal, leaving intact the low‐frequency ones.
An approach to design a circuit (a lowpass filter) whose frequency response satisfies the lowpass requirements consists of two steps: approximation of the requirements by a transfer function and synthesis of the transfer function.
There are several approximation methods, for instance, Butterworth, Chebyshev, inverse Chebyshev, and Cauer approximations. A transfer function obtained by one method is different from those obtained by the others, and has different properties. However, the frequency response of each of the transfer functions satisfies the lowpass requirements.
Magnetic Field Measurement
Authors: Stecher Manfred 
Published: April 2005

AbstractThe measurement of electromagnetic (EM) fields is relevant for various purposes: for scientific and technical applications, for radio propagation, for electromagnetic compatibility (EMC) tests (i.e., testing of the immunity of electronic equipment to electromagnetic emissions aiming at the protection of radio reception from radio interference), and for safety reasons (i.e., the protection of persons from excessive field strengths). For radio propagation and EMC measurements, below about 30MHz a distinction is made between electric and magnetic components of the EM field to be measured. In the area of human safety, this distinction is continued to even higher frequencies.
Magnetic Materials
Authors: van Dover Robert B. 
Published: April 2005

Abstract
Since the early part of the twentieth century, magnetic materials have been the subject of deep and broad research and development because of their economic and scientific importance, and much of our knowledge is mature. Nevertheless, startling discoveries continue to be made, such as the discovery of Nd–Fe–B permanent magnets and the “giant magneto‐resistance” effect in thin‐film multilayers.
Magnetic Microwave Devices
Authors: How Hoton 
Published: April 2005

AbstractMagnetic microwave devices discussed in this article include ferrite junction devices, lumped‐element circulators, nonreciprocal resonators, YIG film and MSW devices, magnetooptic devices, absorbing/antireflection layers, and nonlinear magnetic devices. A general theoretical background underlying the physics for the operation of a ferrite microwave device is first reviewed. Discussions include the derivation of the Polder permeability tensor, the effective fields associated with electron spin motion, the general dispersion spectrum and plane‐wave solutions for electromagnetic wave propagation in a bulk magnetic medium, MSW (magnetostatic waves) admitted by the geometry of a yttrium iron garnet (YIG) film, and the nonlinear instabilities for spin waves occurring at high power, including their routes to chaos. Ferrite junction devices including circulators and isolators are discussed in terms of their bandwidth operation, size reduction, power handling, and other novel issues such as intermodulation noise. The operation of lumped‐element circulators is introduced and the interport impedances outlined. The effective field associated with a magnetic easy plane is defined from an operation point of view. A ferrite nonreciprocal resonator can be used as a phase shifter whose operation is independent of the derived phase shift angles. YIG film devices incorporating magnetostatic waves are introduced, including delay lines, filters, directional couplers, and resonators. Nonlinear magnetic devices are discussed, including frequency‐selective power limiters, signal‐to‐noise enhancers, amplitude correctors, and ferrimagnetic echoing devices. Magnetic solitons include Bloch domain wall solitions and microwave magnetic envelope solitons. Finally, magnetooptic Kerr and Faraday effects and the operation of magnetooptic Bragg diffraction devices are discussed, and the design of microwave absorbing layers and antireflection layers is briefly introduced.
Microstrip Antenna Arrays
Authors: Hall Peter S. 
Published: April 2005

AbstractMicrostrip antenna arrays offer low‐profile solutions to many antenna applications with potentially low cost. Their low profile comes about from the use of microstrip patch radiators fed by microstrip circuit‐based feed networks, or by using the naturally occurring radiation from the feed networks to form a beam. Both patches and microstrip feeds consist of metallic strips or shapes photoetched on one side of a grounded substrate and can be made using conventional photolithographic processes. The use of the microstrip transmission‐line medium, widely used in both hybrid and monolithic radiofrequency circuits, also gives rise to a unique potential for integration with active devices and radio front ends.This article gives an overview of microstrip array architectures. These include parallel‐ and series‐fed arrays and also arrays formed by discontinuities in a microstrip line, such as the serpent and rampart lines. Other forms such as ultrawideband arrays, leaky‐wave arrays, multilayer arrays, sequentially rotated arrays, multibeam arrays, reflect arrays, and active integrated arrays are also described. The article concludes by describing the impact on array design of important factors such as accuracy in pattern synthesis, feed loss and radiation, and mutual coupling.
Microwave Filters
Authors: Zhu Lei 
Published: April 2005

AbstractThis article summarizes the fundamentals of microwave filters with varied frequency‐selective characteristics such as lowpass, bandpass, highpass, and bandstop. On the basis of the ladder network of a lowpass prototype filter, a well‐known synthesis design approach is described to realize the lowpass frequency response in terms of the preselected insertion loss functions and then determine the element values of this network under the Butterworth and Chebyshev function responses. By executing the frequency transformation from the normalized to actual microwave frequency ranges, various lumped‐element microwave filters are first constructed with both series and shunt elements. Next, the immittance inverters are introduced and utilized to eliminate either series or shunt elements, thus alleviating the complexity in filter implementation. In addition to a series of useful design formulas and tables provided with brief explanations, a variety of practical microwave filters are made up using transmission‐line and waveguide elements and their principles are discussed with regard to their equivalent cascaded networks.
Microwave Power Transmission
Authors: Strassner Berndie H. , Chang Kai 
Published: April 2005

AbstractMicrowave power transmission (MPT ) is the wireless transfer of large amounts of power at microwave frequencies from one location to another. MPT is often referred to in the literature as wireless power transmission (WPT ) at microwave frequencies. MPT research has been driven primarily by the desire to remotely power unmanned aerial vehicles (UAV s) and by the concept of space solar power (SSP ) first conceived by Dr. Peter Glaser of the Arthur D. Little Company in 1968. SSP is an MPT system with the addition of solar cells and magnetrons for microwave power generation. The SSP idea calls for a constellation of solar power satellites (SPS s) to capture the energy from the sun using arrays of solar cells. The solar cell panels output large DC voltages to awaiting cavity magnetrons positioned on various subarrays within each SPS phased‐array aperture. These magnetrons convert the high‐voltage DC outputs of the solar panel arrays to microwave power. The microwave energy is then beamed to Earth to farms of rectifying antenna (rectenna) arrays that convert the incoming microwave energy back to DC power. Since its inception, SSP has gained considerable attention since it has the potential of providing clean, renewable, and continuous power for generations to come. MPT has been shown experimentally as a way for people on Earth to remotely power unmanned high‐altitude platforms such as UAV s. Additional uses for MPT include powering space probes from future space stations into deep space and powering robots to enter dangerous environments such as nuclear‐contaminated areas.
Mixed‐Signal CMOS RF Integrated Circuits
Authors: Steyaert Michiel , Reynaert Patrick 
Published: April 2005

AbstractThe world of wireless communication and its applications have begun to grow rapidly. The driving force behind this lies in the introduction of digital coding and digital signal processing in wireless communications. This digital revolution is driven by the development of high‐performance, low‐costCMOStechnologies that allow for the integration of an enormous amount of digital functions on a single die. AsCMOSis mainly a digital technology, placing all digital functions on a single die is merely a matter of handing the system complexity. To achieve a truly single‐chip solution, the analog part also has to be integrated inCMOS.The telecommunication market is generally considered to be a business where a single‐chip solution in a cheap (CMOS) technology results in a huge cost benefit; the main reason is the high volume of user equipment. Furthermore, in these systems, small size, low board area, low power consumption, and high talktime are crucial, and therefore it is of utmost importance to achieve a high level of integration. This trend toward single‐chip, fully integrated systems can clearly be seen in the development of RF systems such asGSM,EDGE, Bluetooth, and wirelessLAN. In all these sytems, the analog part mainly consists of anRFfront end. Deep submicrometer technologies allow for the operation frequency ofCMOScircuits above 1 GHz, which opens the way to fully integratedRFsystems. Several research groups have developed high‐performance downconverters, low‐phase‐noise voltage‐controlled oscillators, and dual‐modulus prescalers in standardCMOStechnologies. The research has already demonstrated fully integrated receivers and synthesizers with no external components, nor tuning or trimming. Further research on low‐noise amplifiers, power amplifiers, and synthesizers has resulted in fully integratedCMOSRFtransceivers for DCS1800, Bluetooth, and wirelessLAN.In this article, we focus on the evolution from the well‐known heterodyne receiver topology to the zero‐ and low‐IF topology used in modern receivers. We also discuss the interaction between the analog part and the digital part regarding substrate noise and decoupling.
Mobile Satellite Communications
Authors: Lodge John 
Published: April 2005

AbstractMobile satellite (MSAT) AU:1 systems provide communications services to mobile and portable terminals using a radiotransmission path between the terminal and the satellite.A wide variety of services and applications are supported by mobile satellite systems, with many more proposed.Third‐generation systems are expected to be capable of transmission at rates up to several hundred kilobits per second and will be capable of delivering moderate‐quality video and high‐quality audio services.A wide variety of mobile satellite terminals is commercially available.
Monte Carlo Analysis
Authors: Lugli Paolo 
Published: April 2005

AbstractAs the name suggests, the Monte Carlo (MC) method is based on the selection of random numbers [1–4]. In its present form, the method is attributed to Fermi, Von Neumann, and Ulam, who developed it for the solution of problems related to neutron transport.Although it will not be possible to exhaust the complexity of the MC methods in such a short review, the present contribution is intended to give a critical overview of the MC algorithms used for device and process modeling and for circuit yield analysis.
Multiconductor Transmission Lines
Authors: Brandão Faria J. A. 
Published: April 2005

AbstractThis article is devoted to the analysis of multiconductor transmission lines (MTLs), a type of structure that is encountered in many applications concerning RF and microwave engineering. Our aim is to provide the reader with a self‐contained presentation of the subject; we start by establishing the time‐domain equations of multiconductor transmission‐line systems and then progress step by step to the final objective of determining the frequency‐domain solution to those equations. Matrix techniques are made intense‐use in order to permit a compact analysis of the problem. Solutions to MTL equations are presented in two different useful formats. At first we consider a solution in the form of a superposition of natural modes of propagation; later, a relationship between voltages and currents at the MTL structure ports is established by employing a transmission matrix. The analysis presented in this article is not limited to the simple case of uniform line structures, as it also encompasses the important problem of nonuniform MTLs.
Dual‐ and Multi‐Frequency Microstrip Antennas
Authors: Lee K.F. , Luk K.M. , Shum Y.H. 
Published: April 2005

AbstractA number of techniques for dual‐band or multiband operation of microstrip antennas are available in the literature. This article introduces the operation principles and design guidelines of several popular methods, including the multimode‐operated patch, stub‐loaded patch, slot‐loaded patch, stacked patch, and coplanar patch antenna. Their relative performances are compared both theoretically and experimentally. One important purpose of the article is to provide physical insight to readers for further development of multiband microstrip antennas, which are attractive for modern wireless applications.
Multiplexers
Authors: Mansour Raafat R. 
Published: April 2005

AbstractMultiplexers are used in communication system applications where there is a need to divide a wideband signal into a number of narrowband signals (channels). They are also employed to provide the opposite function, by combining several narrowband channels into a single wideband channel. Multiplexers are therefore known aschannelizersorcombiners. They find widespread use in many applications such as satellite payloads, wireless systems, and electronic warfare (EW) systems.
Negative Resistance
Authors: King Clifford A. , Ng Kwok K. 
Published: April 2005

Abstract

It is understood that the term negative resistance refers to the dynamic characteristic, that is, the slope of the
I–V
curve (
dV/dI
) is negative.

The negative resistance devices originating from
dV/dI
being negative are discussed, followed by their applications. Finally, similar discussions on the transit‐time devices are presented.
Noise, High‐Frequency
Authors: Agethen M. , Reuter R. , Bertenburg R. M. , Brockerhoff W. , Tegude F. J. 
Published: April 2005

AbstractThe high‐frequency behavior of electronic devices is of major interest in the field of research and development. Beside the typical RF device parameters, like the cutoff frequenciesfTandfmax, the high‐frequency noise behavior should be considered for circuit design, especially if noise has a significant influence on the system performance, for instance, the sensitivity of receivers. Thus, there is a demand for simple, but exact RF noise models that must consider the physically relevant noise phenomena with a significant contribution to the total noise behavior of the device.After an introduction to various physical noise sources, a general description of noisy two‐ports will be presented. Then, a short presentation of a special measurement setup for RF noise in the range of 2–18 GHz with dependence on temperature (15–400 K) is given. In Section 4 RF noise phenomena in certain devices are examined and high‐frequency noise models for heterostructure field‐effect transistors (HFETs) and heterojunction bipolar transistors (HBTs) based on the material system InP are presented. For both devices the capabilities of the model presented will be proved by comparing measured and modeled RF noise parameters. In Section 5 modifications of the HFET noise model and applications of this RF noise model are presented.
Microwave Parametric Amplifiers
Authors: Faber Marek T. 
Published: April 2005

AbstractAn outline of the development of microwave parametric amplifiers (paramps) is presented as an introduction. The principle of their operation is explained leading to the classification of parametric amplifiers and frequency converters. (Photoparametric amplification is also referenced.) Varactor diodes are briefly presented in order to discuss in greater detail the operation of the most significant type of paramp—the nondegenerate parametric amplifier—including gain, noise, bandwidth, and stability. Degenerate, multiple‐idler and traveling‐wave parametric amplifiers are also discussed. Then the construction of a 3.25‐GHz nondegenerate parametric amplifier is presented as a representative example.
Passivation
Authors: Pearton S. J. 
Published: April 2005

AbstractPassivation layers are deposited over the entire top surface of Si or compound semiconductor wafers to form an insulating protective coating for the semiconductor. This procedure guards against environmental contamination that might lead to increased surface leakage currents, and also against mechanical damage during assembly and packaging. Some of the desirable properties of passivation‐layer materials include good scratch protection of the underlying interconnect metallurgy, impermeability to moisture and alkali (Na+, K+) ions, low stress (<5×108 dyn/cm2, preferably compressive), conformal step coverage, and etchability with excellent uniformity and adhesion. While thicker passivation layers would normally be desirable because of the improved mechanical protection they afford, there is generally an upper limit to the thickness in order to avoid cracking. The primary inorganic dielectric passivation films are SiO2and SiNx, while polyimides and epoxy resins are used for low‐cost polymer encapsulation. The thermal stability requirements are obviously lower for final passivation coatings than for interlevel dielectrics.Patterns are formed in the passivation‐layer material by either wet (for phosphosilicate glasses) or dry (for SiNxor polymers) etching to enable electrical contact to the completed circuit. The area of these contact pads is sufficiently large (100×100 μm2) that wet etching is acceptable.
Perturbation Theory
Authors: Mathew K. T. 
Published: April 2005

AbstractPerturbation methods, otherwise known as cavity perturbation methods based on perturbation theory, are simple and accurate methods to solve many of the electromagnetic field problems. This article envisages the basic concepts to evolve the perturbation theory from Maxwell's fundamental equations. Different approaches to this problem are also tackled. The merits, drawbacks, and possible errors of this technique and few of important applications are discussed.
Phase‐Locked Oscillators and Frequency Synthesizers
Authors: Rohde Ulrich L. 
Published: April 2005

AbstractSynthesizers are used to generate frequencies with arbitrary resolution covering the frequency range from audio to millimeter‐wave. Today, simple frequency synthesizers consist of a variety of synthesizer chips, an external voltage‐controlled oscillator (VCO), and a frequency standard. There are also combinations of techniques that I would like to refer to as “hybrid synthesizers.” They will be covered here.
PIN Diodes
Authors: Fathy Aly E. , Rosen Arye 
Published: April 2005

AbstractA PIN diode is a semiconductor device that operates at RF and microwave frequencies as a variable resistor in the forward direction.The PIN diode is useful for leveling, limiting, and amplitude modulating an RF signal, when the control current is varied continuously. However, the device can be used for pulse modulating, attenuating, and phase shifting of an RF signal if the control current is turned ON or OFF, or in discrete steps. In addition, the PINs small size, weight, high switching speed, and minimized parasitic elements make it ideally suited for miniature, broadband RF signal applications.
Q‐Factor Measurements
Authors: Luiten Andre 
Published: April 2005

AbstractThis article presents a review of both traditional and modern methods ofQfactor measurement. Many of the techniques to be described were first developed in order to determine theQfactors of resonances falling in the microwave frequency domain.The article commences with a definition of theQfactor and a description of the experimental parameters that need to be measured so as to determine theQfactor of resonance. The various methods for measuring these parameters will then be outlined, including the particular advantages and disadvantages of a technique, the equipment required for the measurement, and its potential for accuracy. Finally, some of the latest developments in the field ofQmeasurement will be presented.
Radar Altimetry
Authors: Raney R. Keith 
Published: April 2005

AbstractThe article reviews ocean‐observing radar altimeters hosted on spacecraft in low‐Earth orbit. These instruments measure sea surface topography on global and mesoscales to a height accuracy of a few centimeters. Flight missions since 1973 to the present are summarized. The conventional pulse‐limited full‐deramp modulation technique is illustrated by the design of the TOPEX altimeter. The advanced delay–Doppler technique is explained, whose benefits extend to ice‐sheet altimetry (Cryosat), and to improved measurement of oceanic gravity anomalies, hence bathymetry. The article concludes with comments on future directions.
Radar Cross‐Section
Authors: Jenn David C. 
Published: April 2005

AbstractRadar cross section (RCS) is a measure of the magnitude of the scattered electromagnetic wave from a body relative to the magnitude of the wave incident on the body. To many people RCS is synonymous with stealth. Stealth technology has become an integral part of all military systems since it was first employed in the 1970s. However, RCS is just one aspect of stealth, the design philosophy that seeks to make a platform (such as an aircraft, ship, or ground vehicle) undetectable to a wide range of sensors.
Radar Remote Sensing of Irregular Stratified Layers
Authors: Bahar Ezekiel 
Published: April 2005

AbstractA variational full‐wave approach to electromagnetic scattering from irregular stratified media with multiple scale features is presented. Since the scales of the irregular features, such as surface roughness, are often a continuum from very large to very small compared to the wavelength, a two‐scale unified full‐wave approach is applied. The method used to smoothly decompose the random medium fluctuations into larger‐scale and smaller‐scale fluctuations is illustrated for random media characterized by Gaussian and Pearson–Moskowitz‐type spectral density functions. The variational parameter is related to the two‐scale subdivision of the random features of media. It is shown that the total scatter cross section of the irregular stratified media is stationary over a very broad range of the variational parameter. Thus the full‐wave solutions, which are expressed as weighted sums of two cross sections, are practically insensitive to the precise decomposition into two‐scale features.
Radar Signal Detection
Authors: Wang Minsheng , Chan Andrew K. 
Published: April 2005

AbstractOwing to the existence of noise and interference, radar signal detection has to be treated as a statistical problem, regardless of whether the signal under detection is deterministic. This statistical formalism of radar signal detection theory can be applied to all types of radar signals without restriction. To understand radar signal detection, noise has to be described quantitatively. A time‐limited deterministic signal can be described as a time series, and a periodic deterministic signal can be represented as a Fourier series. In contrast, noise cannot be represented as a deterministic function in the time or frequency domains. In other words, we cannot predict a noise‐contaminated radar signal with absolute certainty. However, with available noise information such as the expectation, the power, or even the probability distribution of noise, we can select a criterion on which to base our decision.