bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photonic Bandgap (PBG)
Authors: Martínez Alejandro , Griol Amadeu , Sanchis Pablo , Martí Javier 
Published: November 2024

AbstractPhotonic 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.
Television and FM Broadcasting Antennas
Authors: Bendov O. 
Published: November 2024

Abstract
Antennas for television and FM broadcasting are usually installed on tall towers to maximize the service area. A high‐power transmitter feeds the broadcast antenna to provide “passable” picture and sound at distances approaching 70 m. In the UHF range (TV channels 14 to 69), the transmitter's peak power could be as high as 280kW. In the VHF range (TV channels 2 to 13 and FM), a transmitter's peak power of 70kW is not unusual. In addition to high power‐handling capability, broadcast antennas must continue to perform under severe weather conditions, such as ice storms and hurricane winds. Antennas, especially for television broadcasting, must be designed to accept and radiate all of the power delivered by the transmitter. Antennas for digital television must be designed to meet more stringent specifications than those for antennas for analog television.
Oscillator Design
Authors: Mathis Wolfgang , Russer Peter 
Published: November 2024

AbstractThe behavior of electronic oscillators can be studied completely only if nonlinear circuit models are utilized. In this article the main fundamental aspects of analytical as well as numerical methods for analyzing oscillatory circuits are reviewed. First, electronic oscillators are modeled as nonlinear dynamical systems and analytical perturbation methods and bifurcation theory (e.g., Andronov–Hopf bifurcation) are used to analyze sinusoidal as well as relaxation oscillators. Then the theory of noise in oscillatory circuits is discussed. In the second part of the article state‐of‐the‐art methods for the numerical analysis of deterministic and noisy oscillators are presented. In almost all sections original results of the authors are included. The methods are illustrated by means of a few examples.
Frequency Modulation
Authors: Fertig L. B. , Mc Clellan J. H. 
Published: November 2024

AbstractIn this article, concepts relating to instantaneous frequency, along with algorithms for its computation, are reviewed. First, several means by which instantaneous frequency is commonly defined are discussed, and the relationships between instantaneous frequency and time–frequency distributions are explored. Next, several measures of performance commonly used to evaluate instantaneous frequency algorithms, such as the Cramer–Rao lower bound, are examined. Finally, a number of algorithms that have been suggested for IFE are summarized. Despite the relative maturity of frequency modulation in the field of radiocommunications, the field of IFE is a growing one, and one in which research is still quite active.
Local Area Networks (LAN)
Authors: Evans Joseph B. 
Published: November 2024

Abstract
Local Area Networks (LANs) are data communications networks within offices, homes, or areas as large as campuses. LANs are based on physical technologies ranging from copper wiring and optical fiber to radio systems. There are a number of commonly used and emerging LAN technologies that offer the opportunity to connect computers and all manner of devices such as sensors and instruments to increasingly pervasive networks.
Volterra Modeling in Analog, RF and Microwave Engineering
Authors: Steer Michael B. , Gharaibeh Khaled M. 
Published: November 2024

AbstractVolterra 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.
Ge‐Si Alloys and Devices
Authors: Russer Peter , Luy Johann-Friedrich 
Published: November 2024

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.
III–V Semiconductors
Authors: Snowden Christopher M. 
Published: November 2024

AbstractThis 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.
Radar Remote Sensing
Authors: van Zyl Jakob J. , Kim Yunjin 
Published: November 2024

AbstractIn this article, we present the basic principles of how remote sensing radars work. These include SARs (synthetic aperture radar), scatterometers, altimeters, sounders, cloud radars, and rain radars. Radars are active sensors; they provide their own illumination and therefore can be operated during day or night. An additional advantage of particularly lower‐frequency radars is their ability to penetrate clouds, rain, tree canopies, and even dry soil surfaces. We start the discussion by defining the basic concepts of resolution, the radar equation, signal fading, and the geometric distortions associated with the radar imaging geometry. We also include a description of advanced SAR techniques (polarimetry, interferometry, and polarimetric interferometry) and their applications. We complete the chapter by briefly examining nonimaging radars such as scatterometers, altimeters, radar sounders, and meteorological radars. An extensive list of references is provided for each radar for readers who need an in‐depth description of a particular radar.
Buried Object Detection
Authors: Türk Ahmet Serdar , Hocaoglu Ali Köksal 
Published: November 2024

AbstractThe subsurface detection and identification of the buried geologic and synthetic (human‐produced) structures is currently an important research area. The scope of the problem is very complex and covers a wide range in applications. One area of the research includes the detection of a large metallic gas pipe buried in a deep or small plastic mine laid just beneath the ground. The size, geometry, constitution and depth of the target object and the characteristics of the medium (wet soil, sand, etc.) can be considered as the principal parameters for the detector designs. In this article, different sensor technologies based mainly on electromagnetic, acoustics, infrared, or chemical theories are discussed.
Multiple‐Access Schemes
Authors: Sidi Moshe 
Published: November 2024

AbstractMultiple 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.
Radio‐Frequency Identification Systems (RFID)
Authors: Hayashi Hitoshi 
Published: November 2024

AbstractRadiofrequency 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.
Measurement of Near Fields Using a Modulated Scatterer
Authors: Gardiol Fred 
Published: November 2024

AbstractIn the close vicinity of an electronic device or of an antenna, the electric and magnetic fields often exhibit a complex behavior, and a good knowledge of the resulting field pattern would be a most valuable asset for many practical applications. But when one inserts a probe antenna connected to a receiver, close to the the device, one modifies the filed, because metal locally short‐circuits the tangential electric field components.The modulated scatterer technique provides an indirect approach to determine field components, by introducing a small “scatterer” that does not perturb as much as a receiving probe would. The signal returned by the scatterer is very small, and to detect it one “modulates” the scatterer and then uses coherent detection. The amplitude and the phase of the field components are then determined.
Wavelength Meter
Authors: Guy Martin , Latrasse Christine , Villeneuve Bernard , Têtu Michel , Tremblay Pierre 
Published: November 2024

AbstractWavelength meters are instruments designed to measure the wavelength of an electromagnetic wave. Electromagnetic waves are the classic way to represent modifications of the space surrounding a moving electrically charged body. Time‐varying electric and magnetic fields are produced and can be sensed.Wavelength is a well‐established parameter when considering a monochromatic (single‐frequency) plane wave propagating in vacuum. It is the distance between two planes, measured along the direction of propagation of energy, where the phase and its derivatives have the same values.
Active Filters: Overview of Active Filter Structures
Authors: Billonnet Laurent , Jarry Bernard 
Published: November 2024

AbstractThis article is dedicated to an overview of existing active‐filter structures. We first talk about the different families of filters. We evaluate different ways of classifying microwave active filters (MAFs) and show that two main categories can be finally considered. For the first category, we describe, from a general point of view, various compensation techniques and detail more specifically filters based on the use of gyrators and negative‐impedance converters (NICs). In this step, we emphasize different problems that must be faced by RF and microwave designers in comparison to low‐frequency classical designs. The second category is based on filters resulting from the application, in the microwave domain, of methods and concepts used primarily at low frequency. As an example, this section sums up the different ways of considering and implementing recursive and transversal (R&T) filters for the microwave purpose.
Active Filters: Tools and Techniques for Active Filter Design
Authors: Billonnet Laurent , Jarry Bernard , Barelaud Bruno 
Published: November 2024

AbstractIn this article, we first discuss the use of CAD tools for microwave and RF filter design. We emphasize that, without any strong microwave design background and experience, optimization tools unavoidably lead to nonreproducible solutions. We then show the necessary implementation of analytical procedures to set and verify some essential characteristics of low‐noise active devices, with the examples of electrical stability criteria and noise performance calculation, prediction, and optimization. Section 2 deals with the description of tools and techniques for filter improvements. We begin with an extended consideration of compensation techniques based on response selectivity and circuit dimensions improvement. The technique is illustrated with the design of a one‐pole interdigital filter and a two‐pole coplanar filter whose response and size have been improved using this approach. We then generalise the principle to the active‐impedance profile (AIP ) technique, which is illustrated with the application to multistandard and pseudomultipole filters. Finally, novel approaches and new technologies for new microwave and RF communications needs are detailed. We confront GaAs processes to silicon‐based technologies in terms of processes themselves, and in terms of CAD tools, component implementation, compactness, relative size, and cost with two basic circuit examples. Migration to silicon‐based processes also involves novel implementation approaches, including differential circuits. This last approach is illustrated with experimental results.
Analytical and Adaptive Modeling of Nonlinear High Power Amplifiers
Authors: Ibnkahla Mohamed 
Published: November 2024

AbstractHigh‐power amplifiers are used in modern communication systems for their high‐power efficiency. However, these amplifiers have generally nonlinear characteristics, leading to signal distortion and adjacent channel interference. We review the most popular analytical models for these nonlinear characteristics. A special focus is given to adaptive models—mainly neural network approaches—which have emerged as efficient tools for the modeling, identification, and characterization of nonlinear amplifiers.
Coplanar Stripline Transitions
Authors: Simons Rainee N. 
Published: November 2024

AbstractRF and microwave circuit components can be realized with input/output ports using either balanced or unbalanced planar transmission lines. Interconnections between these components will require a balun or a transition to transform an unbalanced port to a balanced port. This article presents several baluns or transitions, that are of either the Marchand or double‐Y type.
Ferrite Circulators
Authors: Yung E. K. N. , Wang D. X. , Chen R. S. 
Published: November 2024

AbstractThe circulator is one of the elementary building blocks in radiofrequency and microwave circuits. It is used extensively in making basic devices for communications and radar systems. The latter are often used in broadband and high‐power rating systems at microwave and millimeter‐wave frequencies. It is, however, seldom found in consumer products because some of its functions can be performed by simpler and cheaper alternatives. However, interest in circulators has been revitalized with the emergence of mobile communications in recent years. As more and more users are accustomed to the freedom provided by cellular phones, communication without the constraint of an attached wire is considered as natural as breathing air. In addressing the ever‐increasing public demands, numerous wireless systems have been launched and more are coming. The most notable ones are wireless local‐area network, wireless local subscriber loops, and other high‐bit‐rate yet low‐error‐rate systems of data transmission. For these systems, the overlooked circulator enjoys a competitive edge as most active switches could not deliver the needed power rating and bandwidth at a reasonable price, especially those in the ultra high frequency band and beyond.
Low Noise Amplifiers
Authors: Nair Vijay 
Published: November 2024

AbstractThis 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 Ferroelectric Devices
Authors: Patel D. P. , Pond J. M. , Rao J. B. L. 
Published: November 2024

AbstractControl of reactance in microwave circuits, devices, and systems is a common method by which the response of a microwave circuit such as a filter, resonator, or phase shifter can be tuned. Devices based on a class of voltagedependent non‐linear dielectrics known as ferroelectrics provide an alternative to semiconductor varactor diodes and ferrimagnetic components, which are the most common devices of this type.This article describes microwave devices that exploit the variation of the ferroelectric's permittivity with applied DC electric field. The main feature of these “tunable” microwave devices is the change of their capacitance, impedance, or phase velocity. We will describe varactors, oscillators, tunable filters, and phase shifting devices.
Microwave Limiters
Authors: Kaul Roger 
Published: November 2024

AbstractA 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.
Slow Wave Structures
Authors: Wu Ke 
Published: November 2024

AbstractThe slow wave is a particular type of wave propagation, usually of the guided‐wave type, and it is described mostly in the frequency‐domain. Slow‐wave structures are wave‐guides or transmission lines in which the wave travels with a phase velocity equal to or less than a certain predesignated velocity of wave propagation. In other words, the slow wave should be interpreted relative to its fast‐wave counterpart compared with a velocity of reference, such as the speed of light in a hollow metallic waveguide. In this description, the slow‐ and fast‐wave‐guiding properties are simply characterized by a popular technical term called the effective permittivity, which may involve the effect of permeability if the relative permeability is not equal to one, even though the concept of a separate effective permeability is valid.
Stripline Components
Authors: Barrio-Garrido R. M. , Salazar-Palma M. , Sarkar T. K. , Adve R. S. 
Published: November 2024

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.
Waveguides
Authors: Vorst André Vander 
Published: November 2024

AbstractIn the electromagnetic spectrum, microwaves are the waves whose wavelengths are comparable to ordinary laboratory dimensions. Furthermore, smooth surfaces of good conductors form very perfect reflectors for them. As a consequence, an electromagnetic wave in a reflecting pipe is reflected back and forth from wall to wall, so that it can travel to large distances with small attenuation. Hence we have “waveguides” as transmission lines, dealing with electromagnetic fields in the inside of hollow regions, rather than outside wires for more conventional electric applications, or waves in free space as in optics, and the propagating electromagnetic field is confined to the finite region of the guide by reflecting walls. The present article reviews the basic theory and the different geometries used in the various applications of such hollow waveguides. It also reviews specific recent (as of 2003) developments, such as theoretical advances, waveguides with arbitrary cross section, and ridged and grooved waveguides.