bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radar Tracking
Authors: Bruder Joseph A. 
Published: April 2005

AbstractRadar tracking is the ability to determine the position and velocity vector of a target at any particular instant in time, to predict its position in the future, and to distinguish the desired target from other targets and clutter.Target tracking is necessary for a number of reasons. In order to direct a weapon such as a missile or a projectile to a target, the range, future range, and angles from the radar to the target must be determined by the radar. By knowing the position of the target relative to that of the missile, the guidance computer can direct the missile to the target.
Radiation Effects
Authors: Schwank James R. , Sexton Fred W. , Dodd Paul E. , Shaneyfelt Marty R. 
Published: April 2005

AbstractThe effects of the space radiation environment on semiconductor device response are reviewed. Semiconductor devices in space can be exposed to energetic particles that can cause device degradation and system failure. The space environment consists primarily of protons, electrons, and heavy ions. Ionizing radiation (electrons and protons) can induce significant charge buildup in oxides, causing large threshold voltage shifts, and decreases in carrier mobility and bipolar transistor gain. This can result in large increases in the static power current of an IC, degradation in timing, and potential loss of functionality. In the space environment, heavy ions and protons can cause single‐event effects. There are two general classes of single‐event effects: soft errors and hard errors. Soft errors cause no permanent damage and may be correctable. Single‐event upsets are one type of soft error. If the error rate caused by soft errors is too high, performance degradation and even system failure can result. Hard errors cause permanent damage to devices. As integrated circuit technologies advance, they are becoming more prone to soft errors caused by energetic ions. In fact, soft errors caused by energetic particles present in the terrestrial environment and emitted from metal impurities are rapidly making single‐event upset a major reliability concern for ground‐based commercial ICs.
Radio Reception
Authors: Zvonar Zoran 
Published: April 2005

Abstract
Several factors could influence the radio system performance, including radio propagation, radiolink design, radio receiver design, as well as radio network design. The focus of this section is on the most important elements of the radio‐access portion of the system.
Section 1 covers link budget and frequency planning. Sections 2–4 address path‐loss prediction models, outdoor and indoor prediction models, effects of environment and small‐scale variations resulting in multipath fading, with emphasis on channel characterization and statistical propagation models. Section 5 completes the list of external factors that influence radio performance. The aspects of radio design include radio parameters, diversity techniques, modulation and coding, and interference suppression techniques.
Radiowave Propagation Concepts
Authors: Levis Curt A. 
Published: April 2005

Abstract
Although radiowaves also propagate in waveguides, cables, and transmission lines, the term radiowave propagation is used generally, and specifically in this article, for signal travel between a source and a receiver without guidance by such artificial devices. Examples of such systems are radio and television broadcasting, radio point‐to‐point communication, radar, radio navigation, and remote sensing. Much has been learned about radiowave propagation since Hertz first demonstrated wireless transmission from one room to another. Now radiowave propagation is considered a moderately mature science, yet new understanding continues to emerge. This article presents an overview of radiowave propagation concepts.
Radiowave Propagation Ground Effects
Authors: Hill David A. 
Published: April 2005

AbstractRadiowave propagation plays an important role in modern communication, radar, and navigation systems. The mathematical theory of radiowave propagation is based on Maxwells equations [1], which were formulated by James Clerk Maxwell in the 1860s [2]. The first free‐space radiowave transmission experiments between a pair of antennas were performed by Heinrich Hertz in the 1880s [3]. In 1897 Marconi first patented a wireless telegraphy system based on long‐distance, radiowave propagation.
Radiometry
Authors: Glover Ian A. 
Published: April 2005

AbstractRadiometry is concerned with the measurement, analysis, and interpretation of radiant electromagnetic energy. The simplest and most common measurement, made using an instrument called aradiometer, is of received electromagnetic power in a given frequency band. Some instruments, however, analyze the received energys spectral distribution (spectroradiometers), its polarization (polarimeters), or its angular distribution in space (imaging radiometers). The usual objective of radiometric measurements is the inference from them of the physical and/or chemical state of the material from, or through which, the received electromagnetic energy has been emitted, reflected, or transmitted. Radiometry is therefore a branch of remote sensing and could be considered to include radar.
Rectifying Antennas (Rectennas)
Authors: Strassner Bernd H. , Chang Kai 
Published: April 2005

AbstractRectifying antennas, commonly referred to asrectennas, are integral parts of microwave power transmission or wireless power transmission (WPT ) systems. In WPT systems, RF power is transmitted from one location and captured at another location. The term rectenna consists of parts of the words “rectifier” and “antenna” since its function is to absorb incoming radiofrequency (RF ) energy and convert this energy to usable DC power. Advanced concepts for WPT , in which rectennas play a vital role, include the ground–space applications of powering aircraft and high‐altitude platforms remotely as well as space solar power where the sun's energy is transmitted from space in the form of microwaves to Earth's surface. WPT can also be useful in several ground–ground applications, including supplying power to remote locations such as islands where the infrastructure to generate power is either absent or not cost‐effective to build. However, the main future use for WPT is seen in a myriad of space–space applications. These include supplying power to space colonies and space shuttles from nuclear powered satellites. This will enable space explorers to obtain the necessary power needed, at locations far from Earth, to further explore the depths of space.
Reflector Antennas (Parobolic Antennas, Dish Antennas)
Authors: Terada Marco A. B. 
Published: April 2005

AbstractA primer on the reflector antenna art is presented in this article. The initial sections offer an overview of reflector antennas and their main applications at a level suitable for high school and lower‐division college students, as well as the basic principles necessary for the proper understanding of their functionality. The following sections present a more in‐depth treatment of the subject, including methodologies for analyzing and designing practical reflector systems. Finally, advanced topics covering the current state of the art within the field are discussed at a level targeting both graduate students and researchers, as well as the practicioning engineer. An effort is made to illustrate the theory and discussions with examples reflecting real‐world applications.
Resonant Tunneling Diodes
Authors: Maezawa Koichi 
Published: April 2005

AbstractResonant tunneling diodes (RTD s) exploit the quantum tunneling effect emerging in nanometer‐scale thin semiconductor heterostructures. The RTD s feature strong nonlinear current–voltage characteristics exhibiting negative differential resistance and also extremely high operation frequency. These features make the RTD s extremely useful for nonlinear microwave/millimeter‐wave circuits as well as high‐speed digital circuits. The features of RTD s and their applications to high‐frequency circuits are discussed.
Resonators
Authors: Ahn Hee-Ran 
Published: April 2005

AbstractResonators are important components in microwave communication circuits. They create filters and select frequencies in oscillators, amplifiers, tuners, and so on. Fields inside a resonator store energy at the resonance frequency where equal storage of electric and magnetic energies occurs. The input impedance at resonance is purely real because the reactance is proportional to the difference between electric and magnetic energy storage.In this article, series and parallel resonance circuits will be discussed and then the representative resonators that are commonly used in practical cases will be explained.
Silicon‐Germanium
Authors: Schumacher Hermann 
Published: April 2005

AbstractThe introduction of Silicon‐Germanium alloys into the base of bipolar transistors provided a quantum leap in the performance of microwave and millimeter‐wave integrated circuits based on mature Silicon processing. Silicon/Silicon‐Germanium heterostructures can be used in a variety of ways. In bipolar transistors, they may increase the allowable base doping concentration, or speed up charge carrier transport through the base layer. In field‐effect transistors, they may provide carrier confinement, reducing Coulomb scattering and thus increasing the low‐field mobility of electrons and holes. Or, they may be used to introduce an axial strain into Silicon channel layers, again with advantages in charge carrier mobility. The article reviews the principle of SiGe‐based electronic devices, their state‐of‐the‐art, and some microwave circuit applications.
Six‐Port Networks
Authors: Xu Xinyu , Wu Ke , Bosisio Renato G. 
Published: April 2005

AbstractSoftware‐defined radio (SDR) has been identified as a potential method to enhance flexible wireless communication systems. The operation speed of an analog/digital converter (ADC) and processing ability of digital signal processing (DSP) chips are key factors in the development of SDR for useful commercial applications. More recent advances in semiconductor processing technology and the development of reconfigurable devices such as digital signal processors and field‐programmable gate arrays (FPGAs) reduce the development time of commercial products. SDR in conjunction with six‐port receivers has promising applications for use in wireless LANs, audio and television broadcasting, and interoperability between different radio services, as seen by new studies on the use of six‐port technology in various design aspects of a new SDR receiver. The objective is to realize an application of SDR to provide a multichannel, multimode wireless direct digital receiver.The combination of SDR and six‐port technology provides great flexibility in system configuration; significant reduction in hardware cost, particularly at millimeter‐wave frequencies; and potential for software reuse. The six‐port receiver approach offers wideband accommodation to ever‐changing communication specifications required in a SDR as much of its functionality is defined in software. Different types of six‐port circuits have been designed, with center frequencies at 2.4, 5.8, 24, and 28 GHz, operating over wide frequency bands. Some six‐port circuits are based on microstrip structures and are fabricated with hybrid microwave integrated circuit (MHMIC) or monolithic microwave integrated circuit (MMIC) technology at both microwave and millimeter‐wave frequencies. Other circuits use a novel substrate‐integrated waveguide (SIW) structure allowing integration of planar integrated circuit structure with waveguide structure. The performances of these six‐port circuits in digital receivers are reported in relation to signal modulation schemes, noise performance analysis calibration, and coding. Bit error rate simulation and measurement results obtained with demodulation algorithms are given for QPSK and QAM‐16 signals under a variety of operating conditions. Initial results show promising applications of six‐port technology for direct digital conversion demodulation reception, needed in future low‐cost SDR communication systems. Measurement and simulated demodulation results obtained with coding algorithms are also given.
Skin Effect
Authors: Olyslager Frank , de Zutter Daniël 
Published: April 2005

AbstractThe skin effect is the property that electromagnetic waves penetrate only a small distance into a conductor. The fields and induced currents decay exponentially with the distance from the surface. The distance over which the fields and induced currents decrease by a factor ofeis the skin depth. The ratio of the voltage drop along the surface of the conductor to the current flowing in the conductor and causing this voltage drop is the surface impedance. Expressions for the skin depth and the surface impedance are in the first instance derived for a plane conductor interface. The results for a plane conductor are also applicable for a curved conductor as long as the radius of curvature is large compared to the wavelength. For a conductor with a finite thickness an expression for the surface impedance is derived that takes into account the finite thickness of the conductor. The roughness of the conductor surface increases the surface resistance. This increase is quantified by an empirical law. The concept of the surface impedance allows an efficient inclusion of conductors with finite conductivity in numerical electromagnetic simulation techniques such as integral equation techniques, finite‐element techniques, and finite‐difference time‐domain techniques.
Sky Wave Propagation at Medium and High Frequencies
Authors: Davies Kenneth 
Published: April 2005

Abstract
In this article, we shall discuss the following topics: 1. Basic physical properties of sky wave propagation (namely, refraction, reflection, penetration, and absorption) 2. relationships between vertical propagation and oblique propagation 3. ionospheric models 4. characteristics of medium frequencies 5. characteristics of high frequencies 6. prediction programs for ionospheric sky wave performance 7. real‐time channel evaluation
Slot Antennas
Authors: Nakano Hisamatsu 
Published: April 2005

AbstractThe radiation pattern and conductance of a thin straight half‐wavelength slot are derived using an assumed electric field distribution over the slot. Subsequently, Babinet's principle, which provides a relationship between the input impedances of a slot and a conducting plate, both having the same shape, is derived. In addition, an antenna evaluation method based on the finite‐difference time‐domain method is briefly described. Using the finite‐difference time‐domain method, straight, bowtie, loop, curl, and spiral slot antennas are analyzed. The analysis reveals (1) the effects of the finiteness of the conducting sheet, in which the straight slot is cut, on the radiation characteristics; (2) the effects of the bowtie angle on the radiation characteristics; (3) the input impedance of the loop as a function of the circumference; and (4) the frequency responses of the curl and spiral slots, acting as circularly polarized radiation elements.
Spaceborne Radar
Authors: Kwok Ronald , Yueh Simon H. , Fu Lee-Lueng 
Published: April 2005

AbstractHere, we review three different applications of active microwave remote sensing that have contributed geophysical measurements on a scale and accuracy that surpass what could be accomplished with airborne or in situ observations. These are synthetic aperture radar interferometry, scatterometry, and altimetry. For each of these areas, we describe the measurement principle, the current technology, the applications, and give a brief look into the future.
Spiral Antennas
Authors: Cencich Thomas P. , Filipovic Dejan S. 
Published: April 2005

AbstractSpiral antennas were introduced in the mid‐1950s. They were the first antennas to exhibit uniform impedance and pattern performance over multioctave bandwidths. Spirals were the cornerstone and mathematical quintessence of a new concept in antenna theory termedfrequency-independent antennas. In this article, various aspects related to the analysis and design of spiral antennas are discussed. The theory of spiral operation, often referred to asband theory, is discussed. Also included are characteristic geometries and shapes including equiangular and Archimedian planar and conical spirals. Theoretical and practical aspects needed for successful design and understanding of spiral antennas are reviewed. Special attention is given to understanding the modal performance of multiarm spiral antennas and its importance to overall antenna characteristics, analysis theory, mode‐forming networks, multimode excitations, and similar. Various feeding methods including infinite and tapered baluns, as well as coaxial bundles are described. Dual‐polarized spiral designs including inside/outside‐fed spirals and modulated armwidth (MAW ) spirals, and bandwidths of various spiral geometries are discussed. The article also includes some aspects of spiral miniaturization; discussions of challenges of nondissipative cavity backing, utilization of spirals as reflector feeds, the modal decomposition technique; and an overview of numerical methods utilized for successful design of spiral antennas. The article is organized in several sections, each devoted to a separate topic, with illustrations and tables utilized for further clarification and demonstration of discussed concepts.
Squid
s
Authors: Fagaly Robert L. 
Published: April 2005

Abstract
SQUID instruments consist of a SQUID amplifier or sensor and a detection circuit that transforms the signal of interest into a magnetic flux that is detected by the SQUID sensor. Associated control electronics transform this signal into a room temperature voltage that is available for additional signal processing if needed. The SQUID amplifier and the detection coils are superconducting devices. Thus some type of refrigerant (e.g., liquid helium or nitrogen) or refrigeration device is needed to maintain the SQUID (and detection coil) in the superconducting state. Additional signal‐conditioning electronics may be needed to improve the signal‐to‐noise ratio.
Stability of Nonlinear Systems
Authors: Chen Guanrong 
Published: April 2005

AbstractThis article outlines the notion of stability of nonlinear systems, for both continuous‐time and discrete‐time settings. Basic concepts and fundamental theorems of various system stabilities are introduced. These mainly include the important Lyapunov stability theory, along with some others such as the Zhukovskij stability theory and orbital as well as structural stabilities. Bounded‐input bounded‐output stability of maps is also discussed.
Stripline Components
Authors: Barrio-Garrido R. M. , Salazar-Palma M. , Sarkar T. K. , Adve R. S. 
Published: April 2005

AbstractThe fast spread of wireless and high‐speed communications brings the need for providing inexpensive and compact microwave circuits at very high frequencies. A promising approach is the development of the modern multilevel or three‐dimensional monolithic microwave integrated circuits (MMIC), printed circuit boards (PCB), and the new technologies for integration of millimeter‐wave systems like low‐temperature cofire ceramics (LTCC). In such environments, stripline‐like components play a key role and focus a great interest nowadays, because multilayer, embedded transmission line (ETL) based on stripline configurations originates from the three‐dimensional packages. Moreover, stripline is one of the preferred transmission lines in most of this environments because, among other advantages, radiation and dispersion are negligible and ground planes provide effective shielding. For example, in antenna feeding, stripline has probed to be a compact and effective solution. In filter applications, suspended striplines are extensively used by engineers because of their low unloaded Q‐factor. However, the multiconductor and multilayer structures present some complications derived from the shorting posts or via holes, spurious modes that result in crosstalk and losses, complex geometries, and so on. In many cases, it is necessary to find new design solutions to avoid parallel‐plate mode coupling, but full‐wave analysis becomes a complicated task. In this article, these issues are exposed, and both classic stripline components and new multilayer structures are presented. We discuss some design considerations, advantages and drawbacks, classic and new devices, and modern solutions recently reported for old and new necessities of the design and analysis of stripline configurations.
Superconducting Cavity Resonators
Authors: Padamsee Hasan 
Published: April 2005

Abstract
A key component of the modern particle accelerator is the device that imparts energy to the charged particles. This is an electromagnetic radio frequency (RF) cavity resonating at microwave frequencies typically between 50MHz and 3000 MHz. Superconducting cavities economically provide high CW operating fields. Another benefit is that superconducting cavities can be designed to have a large beam aperture that reduces the beam cavity interactions, allowing higher beam quality and higher beam current. There are two distinct types of superconducting cavities, depending on the velocity of the particles. The first category is for accelerating charged particles that move at nearly the speed of light, such as electrons in a high‐energy linear accelerator [e.g., at TJNAF at Jefferson Lab in Newport News, VA] or a storage ring [e.g., LEP at CERN in Switzerland]. The second type is for particles that move at a small fraction (e.g., 0.01 to 0.3) of the speed of light, such as the heavy ions emerging from a dc highvoltage Van de Graaff accelerator.
Superconducting Filters and Passive Components
Authors: O’Callaghan Juan M. , Collado Carlos , Talisa Salvador H. , Mateu Jordi 
Published: April 2005

AbstractThis article gives an overview of the applications of high‐temperature superconductors for passive microwave devices, with an emphasis on planar filters. It includes a description of the basic characteristics of these superconducting materials and relates these characteristics to device performance. In the case of filters, the low loss of superconducting films allows the development of small, planar filters with superior performance. One important application of these filters is preselector filters for receiver front‐ends, because they combine high‐frequency selectivity with low insertion loss and low noise figure because of the low temperatures of operation.The article also gives a short overview of applications of high‐temperature superconducting materials in planar delay lines, cryocoolers, and cryogenic packaging.
Superconducting Microwave Technology
Authors: Choudhury Durga P. , Sridhar S. 
Published: April 2005

AbstractSuperconductivity is a remarkable state of matter in which electric current can flow inside materials without any detectable resistance. In a superconductor, perfect electric conductivity or zero resistivity occurs only below a “critical temperature”TC. A direct current induced in a superconducting ring has been shown to persist for over 2 years without any measurable decay. Another important characteristic of superconductors was the discovery by W. Meissner and R. Ochsenfeld in 1933 that a superconductor expels all magnetic flux from its interior; that is, a superconductor is also a perfect diamagnet. A key area of technological applications of superconductors is in high‐frequency devices, particularly at frequencies in the radiowave, microwave, and millimeterwave spectral ranges.