Showing papers in "IEEE Microwave Magazine in 2012"
TL;DR: With the availability of more channels combined with the powerful digital signal processing (DSP) capabilities of modern computers, the performance of mm-wave imaging systems is advancing rapidly.
Abstract: Due to the enormous advances made in semiconductor technology over the last few years, high integration densities with moderate costs are achievable even in the millimeter-wave (mm-wave) range and beyond, which encourage the development of imaging systems with a high number of channels. The mm-wave range lies between 30 and 300 GHz, with corresponding wavelengths between 10 and 1 mm. While imaging objects with signals of a few millimeters in wavelength, many optically opaque objects appear transparent, making mm-wave imaging attractive for a wide variety of commercial and scientific applications like nondestructive testing (NDT), material characterization, security scanning, and medical screening. The spatial resolution in lateral and range directions as well as the image dynamic range offered by an imaging system are considered the main measures of performance. With the availability of more channels combined with the powerful digital signal processing (DSP) capabilities of modern computers, the performance of mm-wave imaging systems is advancing rapidly.
258 citations
TL;DR: There is an emerging class of small high-performance electronic devices such as mobile phones, electronic toys, home appliances, monitoring and control systems in industrial facilities, and medical diagnosis systems, which are or will be equipped with pill box sized microprocessors or computers as well as sensors.
Abstract: Cheap and ubiquitous sensor systems will shape the coming decades. There is an emerging class of small high-performance electronic devices such as mobile phones, electronic toys, home appliances, monitoring and control systems in industrial facilities, and medical diagnosis systems, which are or will be equipped with pill box sized microprocessors or computers as well as sensors. These “smart sensors” with limited power and processing capabilities are often wirelessly interconnected. An assembly of many of them spread throughout the physical world will form sensor networks able to identify, localize, and monitor physical, environmental, and industrial processes, biological and health conditions, goods, vehicles, factories, stores, or even people.
230 citations
TL;DR: An electronic pill system for a medical monitoring system that travels through the digestive system to collect image data and transfers the data to a nearby computer for display with a distance of one meter or more.
Abstract: Many countries will experience the effects of an aging population, resulting in a high demand of healthcare facilities. Development of novel biomedical technologies is an urgent necessity to improve diagnostic services for this demographic. Electrocar diogram (ECG) and temperature recording have been used for more than 50 years in medical diagnosis to understand various biological activities [1], [2]. A more recent development, electronic pill technology, requires the integration of more complex systems on the same platform when compared to conventional implantable systems. A small miniaturized electronic pill can reach areas such as the small intestine and can deliver real time video images wirelessly to an external console. Figure 1 shows an electronic pill system (i.e., wireless endoscopy) for a medical monitoring system. The device travels through the digestive system to collect image data and transfers the data to a nearby computer for display with a distance of one meter or more. A high resolution videobased capsule endoscope produces a large amount of data, which can then be delivered over a high-capacity wireless link.
122 citations
TL;DR: In this article, the authors focus on the advanced nonlinear device modeling techniques that are the focus of this article, and present a detailed review of the most recent advances in this area.
Abstract: Good transistor models are essential for efficient computer-aided-design (CAD) of nonlinear microwave and RF circuits, monolithic microwave integrated circuits (MMICs), power amplifiers (PAs), and nonlinear RF systems. Increasingly complicated demands of the various semiconductor technologies (e.g., GaAs pHEMTs, InP double heterojunction bipolar transistors (DHBTs), silicon on insulator (SOI), LDMOS, GaN HFETs, etc.), and their applications in terms of power and frequency of operation and complexity of applied signals (e.g., modern communication signals with high peak-toaverage ratios) have placed commensurate requirements on the accuracy and generality of the device models used for design. New semiconductor material systems (e.g., GaN) have been developing at such a fast rate that conventional compact modeling approaches may not be able to keep up. These and other challenges have spawned much research into the advanced nonlinear device modeling techniques that are the focus of this article.
84 citations
TL;DR: High-resolution distance measurements with short- and long-range positioning are important for a large number of sensing applications and can also be used as a precondition for vibrometer applications.
Abstract: Industrial automation today is an essential technology underlying our modern society. Advanced positioning and sensor feedback tasks in automation processes often require distance displacement detection, e.g., to measure and track the movement of robots. Furthermore, the detection of mechanical stress in complex industrial machinery through an accurate vibration analysis is often a task of major interest. Therefore, high-resolution distance measurements with short- and long-range positioning are important for a large number of sensing applications and can also be used as a precondition for vibrometer applications. Several automation technologies rely on high precision positioning sensors to track linear as well as rotational movements of various machinery.
68 citations
TL;DR: These applications demonstrate that the combination of waveguide structure and metamaterials offers an excellent alternative approach to the design of miniaturized and high-performance microwave components.
Abstract: This article summarized and reviewed the realization and applications of the waveguide-based metamaterial structures. In particular, an overview of the existing metamaterial elements was presented. We discussed the possible solutions to enable wave propagation below the waveguide cutoff frequency by loading these elements. Then a detailed analysis on those waveguide unit-cells loaded with different metamaterial elements was provided based on HFSS simulation. Various guided and radiated microwave applications based on these novel metamaterial-based waveguide structures were presented. Those obtained simulation and experimental results were found to be in good agreement with the theoretical prediction. These applications also demonstrate that the combination of waveguide structure and metamaterials offers an excellent alternative approach to the design of miniaturized and high-performance microwave components. Waveguide has high-power handling capability and high Q-factor. It also provides a uniform and lossless e-negative (μ-negative) environment when operated based on the TE modes (TM modes) below the cutoff frequency. This is a promising and potentially rewarding research topic. We are looking forward to achieving more truly high-performance metamaterial devices by taking advantages of these features in the near future.
63 citations
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TL;DR: The market for GaN RF MMICs spans commercial and military applications, including base station, cable television infrastructure, communications, radar and electronic warfare (EW), among others as mentioned in this paper.
Abstract: Gallium nitride (GaN) technology is transforming RF monolithic microwave integrated circuits (MMICs) for power amplifiers (PAs), switches, low noise amplifiers, and more. Vendors are now producing GaN MMICs in volume and achieving outstanding performance. GaNs characteristics enable PA MMICs with 35 times the output power of GaAs alternatives or much smaller die sizes from L-band through Ka-band. High-power switches with low insertion loss up through 18 GHz have been developed. Low-noise amplifiers have been demonstrated with noise figures equivalent to gallium arsenide (GaAs) but with much higher input power survivability. The market for GaN RF MMICs spans commercial and military applications, including base station, cable television infrastructure, communications, radar and electronic warfare (EW), among others.
55 citations
Journal Article•
TL;DR: The concept of SR was introduced in the late 1990s as a successor to digital radio (DR), and referred to a radio transceiver where the antenna signal is sampled directly by an analog-to-digital converter (ADC) in the receive path and coupled directly to a digital-toanalog converter (DAC) inThe transmit path.
Abstract: Over several decades, advances in electronics miniaturization have been the engine for cost and performance gains in both military and commercial systems. More recently, breakthroughs in silicon-based technologies have accelerated the shift towards CMOS system-on-chip (SoC) solutions, combining complex radio-frequency (RF), analog and digital functionality. These advances, along with the introduction of newer generations of communication systems and the unprecedented surge in demand for high data rates, motivated the search for a purely digital solution for all radio standards. This, in turn, with the coexistence of the software revolution has called for the programmability of the communication systems through software to implement a software radio (SR). The concept of SR was introduced in the late 1990s as a successor to digital radio (DR). It referred to a radio transceiver where the antenna signal is sampled directly by an analog-to-digital converter (ADC) in the receive path and coupled directly to a digital-toanalog converter (DAC) in the transmit path.
52 citations
TL;DR: In this article, the authors provide an historical context behind the development of the Doherty and Kahn amplifiers and the history behind their discoveries, as well as the history of the amplifiers themselves.
Abstract: Chireix. Doherty. Kahn. These names are widely heard throughout the power amplifier (PA) industry today when the discussion turns to high-power, high-efficiency amplifiers. When one hears “the Doherty PA is operating at 6 dB output power backoff (OBO) with a 6.5 dB peak to average power ratio,” most PA design engineers are interested in these and other important performance specifications, but what about the names behind the amplifiers themselves. Who were these engineers who have widely used communications amplifiers named after them? This article will attempt to shed a little light on the history behind these engineers and to provide an historical context behind their discoveries.
44 citations
TL;DR: The growth and technology of graphene transistors with an ƒT.LG product of 24 GHz will be discussed and its feasibility for a new generation of applications in RF communications and circuits are discussed.
Abstract: The outstanding properties of graphene have attracted intense research activities to take advantage of this new material for improving existing electronic applications and inventing new ones Some of the target applications include digital and RF electronics, advanced sensors, semitransparent electronics, low power switches, solar cells, and battery energy storage While the lack of bandgap in graphene imposes serious limitations on its application for digital electronics, many RF circuits do not require the existence of a bandgap and can be realized in devices with a low on-off current ratio In this article, we review the recent progress in using graphene for applications in RF and mixed-signal circuits, arguably one of the most promising fields for future graphene electronics
43 citations
TL;DR: The most feared and devastating terrorist weapon is the suicide bomb or person-borne improvised explosive device (PBIED), which is relatively simple to conceal on the body, and successful detection is required at considerable distance or stand-off range before the bomber reaches the target area as mentioned in this paper.
Abstract: There is now, more than ever before, a need for technologies that enable the screening of people from a distance. A wide variety of weapons can be easily concealed under clothing and carried into crowded public sites to target national infrastructure, spread fear, and inflict mass murder and casualties. The most feared and devastating terrorist weapon is the suicide bomb or person borne improvised explosive device (PBIED). Such devices are relatively simple to conceal on the body, and successful detection is required at considerable distance or stand-off range before the bomber reaches the target area.
TL;DR: In this paper, accurate S-parameter characterization techniques above 100 GHz are required for active and passive devices such that compact models may be developed and verified on representative circuits, but at present, most, if not all semiconductor foundries extract their transistor and passive device models from measurements conducted below 110 GHz and often below 65 GHz.
Abstract: Due to the aggressive scaling of metal-oxide-semiconductor field-effect transistors (MOSFETs) and silicon germanium SiGe heterojunction bipolar transistors (HBTs), silicon-based circuits operating above 100 GHz are becoming a reality. However, at present, most, if not all semiconductor foundries extract their transistor and passive device models from measurements conducted below 110 GHz and often below 65 GHz. In order to reduce the number of design iterations, accurate S-parameter characterization techniques above 100 GHz are required for active and passive devices such that compact models may be developed and verified on representative circuits.
TL;DR: In this paper, the differences between envelope tracking, elimination and restoration (EER) and polarizing power supply (PPS) circuits are discussed, and simple and clear definitions as to which is which helps us clearly understand the differences.
Abstract: The terms “envelope tracking” (ET), “evelope elimination and restoration” (EER), and “polar” are generally used interchangeably in the literature for any transmitter circuit built using a dynamic power supply (DPS) architecture on the RF power amplifier (PA). Indeed, these are sometimes combined together into the same category and called EER/ET or ET/EER [1]. It is my experience from more than 15 years working with these technologies that there are very distinct and major differences between these techniques. Establishing simple and clear definitions as to which is which helps us clearly understand the differences between them. More importantly, this allows much less ambiguity as the literature expands regarding these important transmitter techniques.
TL;DR: In this article, a high-efficiency saturated amplifier is presented, which takes advantage of the nonlinear output capacitance to shape the voltage waveform and achieves a PAE of 80.1% at 3.475 GHz.
Abstract: In this article, a high-efficiency saturated amplifier has been presented. This amplifier takes advantage of the nonlinear output capacitor to shape the voltage waveform. The nonlinear capacitor generates substantial second harmonic voltage with small higher order harmonics. Thus, using √2 times larger fundamental load and the proper second harmonic termination, the resultant voltage waveform can be half-sinusoidal. For high efficiency, the PA should be driven by the large input power. Therefore, the current of the PA is bifurcated, resulting in the quasirectangular current shape. The resultant output waveforms are similar to those of class-F1 amplifiers, whose waveforms are optimal for high efficiencies. Based on harmonic source/ load-pull simulation, the saturated amplifier has been designed using Cree's GaN HEMT CGH40006P packaged model. The matching networks for the input and output were optimized using the Momentum simulator. The implemented amplifier delivered a PAE of 80.1% at 3.475 GHz. The simulation and measurement results verify that the saturated amplifier is suitable for a high-efficiency PA over a relatively high frequency band.
TL;DR: In this paper, two main optimization strategies are applied: using dual-band phase offset as an all-pass filter and unequal-power division at the input with distinct power division ratio at two frequencies of operation.
Abstract: This article focuses on the design methodologies and performance optimization strategies of dual-band DPA. The state of art in dual-band DPA has been demonstrated with further considerations for optimizing overall performance. Two main optimization strategies are applied: using dual-band phase offset as an all-pass filter and unequal-power division at the input with distinct power division ratio at two frequencies of operation. The performance improvement with these optimization strategies is demonstrated with a case study of a dual-band DPA operating at 1.96 GHz and 3.5 GHz. The use of stub-loaded dispersive structures has been elaborated on in the design of various dual-band components employed in the dual-band DPA architecture. The dual-band DPA architecture, in theory, can be achieved from direct replacement of each single-band component with conventional dual-band components. In practice, however, several optimization strategies are needed to enhance the performance of the designed dual-band DPA. This article elaborated on some of the optimization strategies with appropriate design examples to demonstrate the use fulness of these optimization strategies.
TL;DR: In this paper, the authors introduce the notion of macroscopic constitutive parameters, such as permittivity and permeability, for electromagnetic metamaterials, which can be obtained from the radio-frequency (RF) and microwave range all the way up to optical frequencies.
Abstract: Electromagnetic metamaterials are artificially structured media with unusual electromagnetic properties that can be engineered from the radio-frequency (RF) and microwave range all the way up to optical frequencies. In its present form, the field of metamaterials is just over ten years old but has already attracted intense interest from many research groups around the globe. Suddenly, classical electromagnetism took on a fresh and exciting perspective, revealing that there are fascinating phenomena still waiting to be discovered and corresponding applications to be invented. In particular, all this excitement is associated with the notion of the macroscopic constitutive parameters, such as the permittivity and permeability. What would be possible if we were able to synthesize electromagnetic materials with arbitrarily valued constitutive parameters? The richness of this possibility becomes more evident when we recall that material parameters can be anisotropic (varying with direction) or spatially inhomogeneous (varying from point to point). Moreover, they can attain values previously not considered (i.e., negative or close to zero), and they can even mix together the electric and magnetic response of a material (chirality).
Journal Article•
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TL;DR: The scope of this article is to provide a comprehensive understanding of design principles for frequency agile and reconfigurable microwave circuits such as power dividers and couplers and how they can be used in radio-frequency (RF)-transceiver subsystems to pave the way toward reconfiguring radio front-end architectures.
Abstract: Over the last decade, mobile communication and its associated mass volume market has become one of the driving forces in the technology evolution of semiconductor and microwave circuits. For handheld communication devices, it is now mainstream to support increasing numbers of communication standards and localization services that occupy ever-expanding wide frequency ranges and bandwidths. At the same time, the physical dimensions of handheld user devices are shrinking, leading to even tighter specifications for the highly integrated front-end architectures of mobile radios. Todays radio front-end architectures use dedicated receive and transmit paths for each covered communication standard, thus the overall complexity and occupied area is increasing as well. The wide frequency allocation of the regulated communication bands along with the variety of standards, which have to be covered by these radios, calls for reconfigurable and frequency agile microwave subsystems. The scope of this article is to provide a comprehensive understanding of design principles for frequency agile and reconfigurable microwave circuits such as power dividers and couplers and how they can be used in radio-frequency (RF)-transceiver subsystems to pave the way toward reconfigurable radio front-end architectures. Introducing reconfigurability in microwave circuits is achieved by tunable passive components. Tunable passives can be implemented in a variety of technologies such as ferroelectric varactors, semiconductor diodes, and microelectromechanical systems (MEMS) components. Attractive applications for tunable circuits in the RF front end are tunable matching networks, filters, reconfigurable power amplifiers, tunable voltage controlled oscillator (VCO) circuits, and finally, couplers and dividers.
TL;DR: In this paper, the authors focus on electrostatically actuated RF MEMS devices, such as RF switches, switched capacitors and varactors, and vibrating RF MEMs resonators.
Abstract: The term radio frequency (RF) microelectromechanical systems (MEMS) refers to electronic devices with a moving submillimeter-sized part (beam, comb, disc, or ring), which provide RF functionality. Alternative definitions include bulk or surface micromachined devices, such as thin film bulk acoustic resonators (FBARs), which rely on energy transduction from the electrical energy domain to the acoustic energy domain and vice versa to provide RF functionality. Many introductory articles and textbooks have been written on MEMS and RF MEMS. This article focuses on electrostatically actuated RF MEMS devices, such as RF MEMS switches, switched capacitors and varactors, and vibrating RF MEMS resonators.
TL;DR: The ambition of achieving road traffic without serious injuries, since 1997 referred to as “Vision Zero,” has influenced the development of new car generations during the last decades and an increasing list of applications already covers comfort and safety functions for various traffic conditions.
Abstract: The ambition of achieving road traffic without serious injuries, since 1997 referred to as “Vision Zero,” has influenced the development of new car generations during the last decades. Since the early beginnings, radar sensors have taken responsibility for receiving this goal and played a major role for achieving the subsequent vision of accident-free driving. An increasing list of applications already covers comfort and safety functions for various traffic conditions. Besides already established applications like adaptive cruise control (ACC) as illustrated in Figure 1, other examples are the lane change assistant (LCA), watching for traffic when starting an overtaking maneuver (see Figure 2) and cross traffic alert (CTA), warning of approaching vehicles at a junction. However, those examples are just a few of the constantly increasing list of functions [1][2].
TL;DR: In this article, the status of millimeter wave CMOS PAs and various circuit design techniques are summarized and discussed for next-generation millimeter-wave high-speed wireless communication systems.
Abstract: This article summarizes the status of millimeterwave CMOS PAs and presents various circuit design techniques. The article shows that millimeter wave CMOS PAs are still a bottleneck for millimeter wave system integration and more circuit design effort has to be devoted for millimeter wave PAs implementation along with the development of the nanometer CMOS technologies. The article also shows that fully integrated millimeter wave CMOS PAs using combining structures will be very important for next-generation millimeter-wave high-speed wireless communication systems.
TL;DR: Radar- based distance control mostly interacts with cruise control systems and it adapts the speed of the driver's car to the distance to the car or obstacle in front of the vehicle.
Abstract: The market for driver-assistance systems for modern automobiles is rapidly growing. Formerly only provided for the luxury automotive market, these systems are nowadays more and more available for mid- and compact-class vehicles as well. This development is not only limited to the passenger car segment but is also more and more important for commercial vehicles and trucks. Some driving assistance systems have already become mandatory, e.g., the antilock breaking system (ABS). Some governments are currently thinking about requiring automatic distance control by law for heavy trucks. Automatic distance control in combination with an automatic emergency breaking system is one of the rising stars for enhancing traffic safety. Radar- based distance control mostly interacts with cruise control systems and it adapts the speed of the driver's car to the distance to the car or obstacle in front of the vehicle. Furthermore, unavoidable accidents are detected and actions for reducing the effects of the crash are automatically initiated for some systems.
TL;DR: In this article, a 120 GHz-band 10-Gb/s wireless link using an InP-HEMT-based MMIC was introduced for last-mile access of 10GbE, live-relay transmission for 4K cinema, and multiplexed HD videos.
Abstract: A 120-GHz-band 10-Gb/s wireless link using an InP-HEMT-based MMIC was introduced. This link is suitable for last-mile access of 10GbE, live-relay transmission for 4K cinema, and multiplexed HD videos. The transmitter and receiver MMICs were developed to extend the link distance while maintaining the capacity of 10 Gb/s. The 120-GHz wireless link using the MMICs successfully demonstrated wireless transmission of 10GbE over the link distance of over 5 km. We also designed QPSK modulator and demodulator MMICs to improve the spectral efficiency of the wireless link. Fabricated QPSK MMICs and modules performed 10-Gb/s transmission with the BER of 10-10 at the received power of -38.5 dBm. In the future, we hope to implement QPSK modules in the 120-GHz-band wireless link equipment. We would also like to advance the QPSK modulator and demodulator MMICs and modules to handle bit rates of up to 20 Gb/s.
NEC1
TL;DR: An overview of CR systems is presented and design challenges for implementing RF integrated circuits (RFICs) are described, including a design example of a wideband CMOS receiver for such systems.
Abstract: Demand for efficient operation of radio frequency (RF) devices with limited resources, such as energy and frequency spectrum, is increasing as a variety of wireless applications quickly become more popular. Cognitive radio (CR), which can sense a radio environment and use an unoccupied spectrum, is thought to be a drastic solution for problems such as battery life shortage and/ or spectrum scarcity. This article presents a brief overview of CR systems and describes design challenges for implementing RF integrated circuits (RFICs). A design example of a wideband CMOS receiver for such systems is also discussed.
TL;DR: This article presents a brief review of the concept of optical metatronics, i.e., the metamaterial-inspired optical nanocircuitry that my group has introduced and developed in recent years, which has the potential to provide a new platform for optical information processing at the nanoscale, with ultrafast, low-power, high-bandwidth, and deeply miniaturized operation.
Abstract: This article presents a brief review of the concept of optical metatronics, i.e., the metamaterial-inspired optical nanocircuitry that my group has introduced and developed in recent years. In this paradigm, deeply subwavelength nanostructures, when judiciously designed and properly arranged, may act as optical lumped nanocircuit elements, thus extending the concept of circuit elements from the RF and microwave into the optical frequencies. Collections of such optical lumped elements provide functionalities that resemble their RF circuit counterparts while operating with light. Such metatronic circuitry has the potential to provide a new platform for optical information processing at the nanoscale, with ultrafast, low-power, high-bandwidth, and deeply miniaturized operation.
Abstract: Software design programs often assist RF/ microwave engineers in creating high-frequency printed circuit boards (PCBs). A multitude of commercial software tools are available, from electromagnetic (EM) simulation programs to circuit layout and complete system simulators. Both engineers and software tools try to forecast the effects of various circuit- and material-based parameters, but some factors may be overlooked or simply not well enough understood to be properly accounted for in a software simulation of a PCB design. This article intends to help RF/microwave PCB designers better understand the different influences affecting high-frequency PCB loss performance, such as copper roughness, solder mask, plated finishes, and circuit configurations, and how to more accurately predict their effects on final PCB insertion-loss (IL) performance.
TL;DR: The U.S. Department of Defense (DoDDoD) began its microwave and millimeter-wave monolithic integrated circuits (MIMIC) program in 1989 as discussed by the authors.
Abstract: It has now been more than a quarter of a century since the U.S. Department of Defense (DoD) began its microwave and millimeter-wave monolithic integrated circuits (MIMIC) program. During that time, the Cold War ended and, as a result, there was a dramatic consolidation of defense companies. Many engineers, scientists, and others who participated in the program have changed companies, changed jobs, retired and, in some cases, died. The legacy of the program, however, remains: the establishment of the capabilities, infrastructure, and knowledge necessary to design and produce GaAs MMICs for nearly any application with high yield, at low cost, and possessing the specific performance and reliability characteristics required for their use in a huge number of system applications, both military and commercial [1][3]. This, in turn, has resulted in the United States' becoming the world leader in GaAs MMIC technology, a position that it still holds. The program played a major role in disproving the once popular statement that “GaAs is the material of the future and always will be.” This article describes the beginnings of the program and the strategy it used to achieve its goals. It also summarizes what has been accomplished and offers some advice based on the experience gained over the course of the program.
TL;DR: The second and third generation of MEMS oscillators will target a larger market for compact oscillators in order to meet TCXO and OCXO performance requirements, which will produce further synergies for the industry as mass production becomes cheaper and easier as mentioned in this paper.
Abstract: The second and third generation of MEMS oscillators will target a larger market for compact oscillators in order to meet TCXO and OCXO performance requirements. While silicon-based timing devices are still not as capable as crystal oscillators of undertaking sophisticated tasks , they are getting better, and will eventually replace crystals in many contexts. That will produce further synergies for the industry as mass production becomes cheaper and easier. These days, designers require higher frequencies and low jitter in oscillators, while buyers demand low cost and quick delivery. Timely oscillator options that can deliver the highest desired performance, while minimally compensating design steps are the key to cost-effective solutions. Fortunately, in the ongoing battle to push the limits of technology and lower component costs, oscillator manufacturers continue to close the gap between highlevel performance and cost-effective purchasing, with conventional crystal technology paired with configurable oscillator technology. Like every exciting new technology targeting mass markets and driven by start-ups, confusion or exaggeration are present, but all in all, we believe that MEMS oscillators will follow the successful bulk acoustic wave devices as the second RF MEMS mass product.
TL;DR: Software defined radio technology addresses these formats with the idea that a single platform can be reprogrammed to process a variety of waveforms.
Abstract: Modern communication systems comprise a variety of formats, protocols, and frequency ranges. Software defined radio (SDR) technology addresses these formats with the idea that a single platform can be reprogrammed to process a variety of waveforms. The SDR Forum and the IEEE have defined SDR as a radio in which some or all of the physical layer functions are defined in software [1].
TL;DR: In this paper, the authors present a new theory to explain the negative refraction in bulk metamaterials, which does not rely on the existence of a single mode of propagation in materials with negative constitutive parameters.
Abstract: In this article, we present a new theory to explain the phenomenon of negative refraction in bulk metamaterials. Unlike earlier theories, it does not rely on the existence of a single mode of propagation in materials with negative constitutive parameters. It is based on the interaction and phase reversal effects caused by the existence of two simultaneous electromagnetic (EM) modes in uniform inhomogeneous metamaterial structures. The theory is general in the sense that it may be applied with equal validity to quasilumped circuit-based microwave metamaterials and to optical negative refraction in bulk nanowire metamaterials. Validity of the theory is demonstrated with EM simulations of microwave and optical metamaterials.
TL;DR: Behavioral models, which are often used to characterize the time- or frequency- dependent behavior of an electronic component while taking all electromagnetic phenomena into account, are used for design space exploration, design optimization, and sensitivity analysis.
Abstract: Behavioral models such as macromodels, surrogate models, metamodels, and response surface models have many applications in diverse research domains such as aerodynamics [1], hydrology [2], mechanical engineering [3], and many more. When considering the design flow of electronic devices, these models are often used to characterize the time- or frequency- dependent behavior of an electronic component while taking all electromagnetic (EM) phenomena into account: crosstalk, attenuation, dispersion, and coupling effects for example [4]. Such models are of crucial importance for efficient design space exploration, design optimization, and sensitivity analysis [5], [6]. A key advantage is that they are calculated independently of the device's physics and that they are valid for over a wide range of design variables, taking into account multiple geometrical layout or substrate features. Additionally, the models can easily be linked together in a model cascade.