Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 2002"

Planar negative refractive index media using periodically L-C loaded transmission lines

Abstract: Recent demonstrations of negative refraction utilize three-dimensional collections of discrete periodic scatterers to synthesize artificial dielectrics with simultaneously negative permittivity and permeability. In this paper, we propose an alternate perspective on the design and function of such materials that exploits the well-known L-C distributed network representation of homogeneous dielectrics. In the conventional low-pass topology, the quantities L and C represent a positive equivalent permeability and permittivity, respectively. However, in the dual configuration, in which the positions of L and C are simply interchanged, these equivalent material parameters assume simultaneously negative values. Two-dimensional periodic versions of these dual networks are used to demonstrate negative refraction and focusing; phenomena that are manifestations of the fact that such media support a propagating fundamental backward harmonic. We hereby present the characteristics of these artificial transmission-line media and propose a suitable means of implementing them in planar form. We then present circuit and full-wave field simulations illustrating negative refraction and focusing, and the first experimental verification of focusing using such an implementation.

Power amplifiers and transmitters for RF and microwave

Abstract: The generation of RF/microwave power is required not only in wireless communications, but also in applications such as jamming, imaging, RF heating, and miniature dc/dc converters. Each application has its own unique requirements for frequency, bandwidth, load, power, efficiency, linearity, and cost. RF power is generated by a wide variety of techniques, implementations, and active devices. Power amplifiers are incorporated into transmitters in a similarly wide variety of architectures, including linear, Kalm, envelope tracking, outphasing, and Doherty. Linearity can be improved through techniques such as feedback, feedforward, and predistortion.

Ferrite devices and materials

Abstract: The development and current status of microwave ferrite technology is reviewed in this paper. An introduction to the physics and fundamentals of key ferrite devices is provided, followed by a historical account of the development of ferrimagnetic spinel and garnet (YIG) materials. Key ferrite components, i.e., circulators and isolators, phase shifters, tunable filters, and nonlinear devices are also discussed separately.

Propagation prediction models for wireless communication systems

Abstract: A comprehensive review of the propagation prediction models for terrestrial wireless communication systems is presented in this paper. The classic empirical models are briefly described and the focus is placed on the application of ray-tracing techniques to the development of deterministic propagation models. Schemes to increase the computational efficiency and accuracy are discussed. Traditional statistical models are also briefly reviewed for completeness. New challenges to the propagation prediction are described and some new approaches for meeting these challenges are presented.

The global positioning system

Abstract: The paper provides a top-level perspective on how the global positioning system works, how its services are used, and delves into the most important technical and geo-political factors affecting its long-term availability in an international setting.

Concurrent multiband low-noise amplifiers-theory, design, and applications

Abstract: The concept of concurrent multiband low-noise-amplifiers (LNAs) is introduced. A systematic way to design concurrent multiband integrated LNAs in general is developed. Applications of concurrent multiband LNAs in concurrent multiband receivers together with receiver architecture are discussed. Experimental results of a dual-band LNA implemented in a 0.35-/spl mu/m CMOS technology as a demonstration of the concept and theory is presented.

Distributed active transformer-a new power-combining and impedance-transformation technique

Abstract: In this paper, we compare the performance of the newly introduced distributed active transformer (DAT) structure to that of conventional on-chip impedance-transformations methods. Their fundamental power-efficiency limitations in the design of high-power fully integrated amplifiers in standard silicon process technologies are analyzed. The DAT is demonstrated to be an efficient impedance-transformation and power-combining method, which combines several low-voltage push-pull amplifiers in series by magnetic coupling. To demonstrate the validity of the new concept, a 2.4-GHz 1.9-W 2-V fully integrated power-amplifier achieving a power-added efficiency of 41% with 50-/spl Omega/ input and output matching has been fabricated using 0.35-/spl mu/m CMOS transistors.

A high-efficiency dual-frequency rectenna for 2.45- and 5.8-GHz wireless power transmission

Abstract: A dual-frequency printed dipole rectenna has been developed for the wireless power transmission at 2.45- and 5.8-GHz (industrial-scientific-medical bands). For operating at dual band, a new uniplanar printed dipole antenna is developed using a coupling method. A GaAs Schottky barrier diode analysis is performed, and a proper device requirement is discussed to have high RF-to-dc conversion efficiencies at both frequencies. A novel coplanar stripline (CPS) low-pass filter integrated with two additional open-ended T-strip CPS bandstop filters effectively block higher order harmonics generated from the diode. The measured conversion efficiencies achieved at free space are 84.4 and 82.7% at 2.45 and 5.8 GHz, respectively.

Phased arrays - part 1: theory and architectures

Abstract: An overview of electronically scanned array technology with a brief introduction of the basic theory and array architectures are presented. Implementations, current state-of-the-art, and future trends are briefly reviewed in Part II of this paper.

Imaging of biomedical data using a multiplicative regularized contrast source inversion method

Abstract: In this paper, the recently developed multiplicative regularized contrast source inversion method is applied to microwave biomedical applications. The inversion method is fully iterative and avoids solving any forward problem in each iterative step. In this way, the inverse scattering problem can efficiently be solved. Moreover, the recently developed multiplicative regularizer allows us to apply the method blindly to experimental data. We demonstrate inversion from experimental data collected by a 2.33-GHz circular microwave scanner using a two-dimensional (2-D) TM polarization measurement setup. Further some results of a feasibility study of the present inversion method to the 2-D TE polarization and the full-vectorial three-dimensional measurement will be presented as well.

HF, VHF, and UHF systems and technology

Abstract: A wide variety of unique systems and components inhabits the HF, VHF, and UHF bands. Many communication systems (ionospheric, meteor-burst, and troposcatter) provide beyond-line-of-sight coverage and operate independently of external infrastructure. Broadcasting and over-the-horizon radar also operate in these bands. Magnetic-resonance imaging uses HF/VHF signals to see the interior of a human body, and RF heating is used in a variety of medical and industrial applications. Receivers typically employ a mix of analog and digital-signal-processing techniques. Systems for these frequencies make use of RF-power MOSFETs, p-i-n diodes, and ferrite-loaded transmission-line transformers.

Microwave photonics

Abstract: The low-loss wide-bandwidth capability of optoelectronic systems makes them attractive for the transmission and processing of microwave signals, while the development of high-capacity optical communication systems has required the use of microwave techniques in optical transmitters and receivers. These two strands have led to the development of the research area of microwave photonics. This paper describes the development of microwave photonic devices, describes their systems applications, and suggests likely areas for future development.

Adaptive synthesis and design of resonator filters with source/load-multiresonator coupling

Abstract: The paper presents a universal and comprehensive synthesis technique of coupled resonator filters with source/load-multiresonator coupling. The approach is based on repeated analyses of a circuit with the desired topology; no similarity transformation is needed. Restrictions imposed by the implementation on the coupling coefficients such as signs and orders of magnitudes are straightforwardly handled within this technique. The technique is then used to synthesize and design filters with full or almost full coupling matrices by selecting, among the infinite number of solutions, the matrix that corresponds to the actual implementation. In such cases, analytical techniques and those based on similarity transformations cannot be used since they provide no mechanism to constrain individual coupling coefficients in order to discriminate between two full coupling matrices, which are both solutions to the synthesis problem. Using the technique described in this paper, a filter designer can extract the coupling matrix of a filter of arbitrary order and topology while enforcing relevant constraints. There is no need to master all the different existing similarity-transformation-based techniques and the topologies to which they are applicable. For the first time, detailed investigations of parasitic coupling effects, for either compensation or utilization, are made possible. The method is applied to the synthesis of a variety of filters, some of which are then designed and built and their response measured.

Dielectric materials, devices, and circuits

Abstract: Dielectric materials are continuing to play a very important role in the microwave communication systems. These materials are key in realization of low-loss temperature-stable resonators and filters for satellite and broadcasting equipment, and in many other microwave devices. High dielectric-constant materials are critical to the miniaturization of wireless systems, both for the terminals and base-stations, as well as for handsets. In this paper, a sequential evolution of the dielectric materials applications in microwave devices will be reviewed. This includes dielectric waveguides, low-loss temperature-stable ceramic materials, dielectric resonators, and filters. The recent advances in the multilayer circuit modules, dielectric antennas, and ferroelectrics are also described.

A design of the novel coupled-line bandpass filter using defected ground structure with wide stopband performance

Abstract: In this paper, a novel three-pole coupled-line bandpass filter with a microstrip configuration is presented. Presented bandpass filters use defected ground structure (DGS) sections to simultaneously realize a resonator and an inverter. The proposed coupled-line bandpass filter provides compact size with low insertion-loss characteristic. Furthermore, a DGS shape for a microstrip line is newly proposed. The proposed DGS unit structure has a resonance characteristic in some frequency band. The proposed coupled-line filter can provide attenuation poles for wide stopband characteristic due to resonance characteristic of DGS. The equivalent circuit for the proposed DGS unit section is described. The equivalent-circuit parameters for DGS are extracted by using a three-dimensional finite-element-method calculation and simple circuit analysis method. A design method for the proposed coupled-line filter is derived based on coupled-line filter theory and the equivalent circuit of the DGS. The experimental results show excellent agreements with theoretical simulation results.

Design of microwave filters

Abstract: A survey of the major techniques used in the design of microwave filters is presented in this paper. It is shown that the basis for much fundamental microwave filter theory lies in the realm of lumped-element filters, which indeed are actually used directly for many applications at microwave frequencies as high as 18 GHz. Many types of microwave filters are discussed with the object of pointing out the most useful references, especially for a newcomer to the field.

Differentially driven symmetric microstrip inductors

Abstract: A differentially excited symmetric inductor that enhances inductor quality (Q) factor on silicon RFICs is presented. Compared with an equivalent single-ended configuration, experimental data demonstrate that the differential inductor offers a 50% greater Q factor and a broader range of operating frequencies. Predictions from full-wave simulations and a physics-based SPICE-compatible model are validated by experimental measurements on an inductor fabricated in a triple-level metal silicon technology. Application of the symmetric inductor to a cross-coupled oscillator improves output voltage swing and phase noise by 75% and 1.8 dB, respectively (for a given power consumption), while chip area is reduced by 35% compared to conventional inductor equivalents.

Microwave filters-applications and technology

Abstract: This paper describes the development of microwave filter technology from an applications perspective. Military applications required wide-band and tunable devices for electronic support measures receivers, which led to the development of highly selective wide-band waveguide filters, coaxial resonator and suspended-substrate multiplexers, and electronically tunable filters. The satellite communications industry created demand for low-mass narrow-band low-loss filters with severe specifications on amplitude selectivity and phase linearity. These requirements resulted in the development of dual-mode waveguide and dielectric-resonator filters, and advances in the design of contiguous multiplexers. Cellular communications base-stations demanded low-loss high power-handling selective filters with small physical size, capable of being manufactured in tens of thousands at a reasonable cost. These demands led to advances in coaxial resonator, dielectric resonator, and superconducting filters, and also to methods of cost-reduction, including computer-aided alignment. Cellular radio handsets have required the manufacture of hundreds of millions of extremely small very low-cost filters, still with reasonably low loss and high selectivity. This has driven significant advances in integrated ceramic, surface, and bulk acoustic-wave active filters and filters using micromachined electromechanical systems.

Applications of RF/microwaves in medicine

Abstract: Medical applications of RF/microwaves are highlighted in this paper. The emphasis is placed on newer emerging diagnostic and therapeutic applications, such as microwave breast cancer detection, and treatment with localized high power used in ablation of the heart, and liver, benign prostate hypertrophy, angioplasty, and others. A very brief outline of biological effects of RF/microwaves and associated issues is given as background to the applications.

A comprehensive explanation of distortion sideband asymmetries

Abstract: This paper presents a comprehensive study of intermodulation-distortion response asymmetries often observed in microwave nonlinear systems subject to a two-tone or multitone test. The reasons for the different amplitudes of the two adjacent tones are first investigated under small- and large-signal regimes, using a general circuit with frequency-dependent embedding impedances and resistive and reactive nonlinearities. It is shown that this intriguing phenomenon can be mainly attributed to the terminating impedances at the baseband or difference frequencies. Multitone behavior is also addressed and its main differences from the two-tone case explained. Those theoretical conclusions are then extrapolated for real circuits and validated by measured results obtained from microwave power amplifiers of two different technologies, i.e., a GaAs MESFET and an Si bipolar junction transistor.

Wide-scan spherical-lens antennas for automotive radars

Abstract: A new approach to wide scan-angle antennas at millimeter-wave frequencies is introduced with special focus on ease of manufacturing and reliability. The system is composed of planar feed antennas (tapered-slot antennas), which are positioned around a homogeneous spherical Teflon lens. Beam scanning can be achieved by switching between the antenna elements. The spherical-lens system is analyzed through a combined ray-optics/diffraction method. It is found that a maximum efficiency of 50%-55% can be achieved using Teflon, Rexolite, or quartz lenses. The efficiency includes taper, spillover, and reflection loss. Calculations also indicate that the maximum lens diameter is 30-40 /spl lambda//sub 0/, which results in a maximum directivity of 39.5-42 dB. Measurements done on a single-element feed and a 5-cm Teflon lens agree very well with theory and result in a 3-dB beamwidth of 5.5/spl deg/ and better than -20-dB sidelobe levels at 77 GHz. Absolute gain measurements show a system efficiency of 46%-48% (including dielectric loss). A 23- and 33-element antenna array with a scan angle of /spl plusmn/90/spl deg/ and a -3.5- and -6-dB crossover, respectively, in the far-field patterns was also demonstrated. The 23-element array resulted in virtually no gain loss over the entire 90/spl deg/ scan angle. This represents, to our knowledge, the first wide scan-angle antenna at millimeter-wave frequencies.

5-GHz CMOS wireless LANs

Abstract: This paper first provides an overview of some recently ratified wireless local-area network (WLAN) standards before describing an illustrative 5-GHz WLAN receiver implementation. The receiver, built in a standard 0.25-/spl mu/m CMOS logic technology, exploits several recent developments, including lateral-flux capacitors, accumulation-mode varactors, injection-locked frequency dividers, and an image-reject low-noise amplifier. The receiver readily complies with the performance requirements of both IEEE 802.11a and ETSI HiperLAN. It exhibits a 7.2-dB noise figure, as well as an input-referred third-order intercept and 1-dB compression point of -7 and -18 dBm, respectively. Image rejection for this double conversion receiver exceeds 50 dB throughout the frequency band without using external filters. Leakage out of the RF port from the local oscillators is under -87 dBm, and all synthesizer spurs are below the -70-dBm noise floor of the instrumentation used to measure them. The receiver consumes 59 mW from a 1.8-V supply and occupies only 4 mm/sup 2/ of die area, in no small measure due to the use of fractal capacitors for ac coupling.

Quantifying memory effects in RF power amplifiers

Abstract: This paper proposes a system-level behavioral model for RF power amplifiers (PAs), which exhibit memory effects, that is based on the parallel Wiener system. The model extraction is performed using two-tone intermodulation distortion (IMD) measurements with different tone frequency spacings and power levels. It is found that by using such a model, more accurate adjacent-channel power-ratio levels may be predicted for high PAS close to the carrier frequency. This is validated using IS-95B CDMA signals on a low-power (0.5 W) class-AB PA, and on a high-power (45 W) class-B PA. The model also provides a means to quantify memory effects in terms of a figure-of-merit that calculates the relative contribution to the IMD of the memoryless and memory portion of the PA nonlinearity. This figure-of-merit is useful in providing an estimate of the amount of correction that a memoryless predistortion system may have on PAS that exhibit memory effects.

Quasi-optical and spatial power combining

Abstract: Quasi-optical power-combining techniques have been developed to address fundamental limitations in solid-state devices and circuits. These techniques have been applied to oscillators, amplifiers, frequency-conversion components, and control circuits. This paper surveys progress in the development of quasi-optical array systems operating in the microwave and millimeter-wave regime, focusing primarily on the progress in power amplifiers.

Phased arrays-part II: implementations, applications, and future trends

Abstract: In part I of this paper, we presented the basic architectures and theory for passive and active phased arrays. Here, we review array implementation, state-of-the-art applications, and identify future trends in phased-array technology.

Microwave acoustic materials, devices, and applications

Abstract: This paper surveys applications of acoustic waves in microwave devices. After a general and historical introduction to bulk acoustic waves (BAWs), surface acoustic waves (SAWs), practical wave types, and acoustoelectric transducers, a review is given of technologically important materials for microwave acoustic applications. Following this, we discuss BAW and SAW microwave devices and their technologies. Specifically reviewed are thin-film resonators and filters, transversal filters, and filters for correlative analog signal processing. Finally, an overview of the most important microwave applications is given, along with manufacturing and packaging issues.

An MOS transistor model for RF IC design valid in all regions of operation

Abstract: This paper presents an overview of MOS transistor modeling for RF integrated circuit design. It starts with the description of a physical equivalent circuit that can easily be implemented as a SPICE subcircuit. The MOS transistor is divided into an intrinsic part, representing mainly the active part of the device, and an extrinsic part responsible for most of the parasitic elements. A complete charge-based model of the intrinsic part is presented. The main advantage of this new charge-based model is to provide a simple and coherent description of the DC, AC, nonquasi-static (NQS), and noise behavior of the intrinsic MOS that is valid in all regions of operation. It is based on the forward and reverse charges q/sub f/ and q/sub r/ defined as the mobile charge densities, evaluated at the source and at the drain. This intrinsic model also includes a new simplified NQS model that uses a bias and frequency normalization allowing one to describe the high-order frequency behavior with only two simple functions. The extrinsic model includes all the terminal access series resistances, and particularly the gate resistance, the overlap, and junction capacitances as well as a substrate network. The latter is required to account for the signal coupling occurring at RF from the drain to the source and the bulk, through the junction capacitances. The noise model is then presented, including the effect of the substrate resistances on the RF noise parameters. All the aspects of the model are validated for a 0.25-/spl mu/m CMOS process.

Performance of a planar filter using a 0/spl deg/ feed structure

Abstract: The advantage of using a 0/spl deg/ feed structure in filter design is that two extra transmission zeros are created in the stopband while the passband response remains unchanged. This feed structure is analyzed by using transmission matrices. A new lumped-circuit model for a coupled resonator filter is then proposed to take into account the effects of this feed structure. Finally, the feed structure is applied to the design of a cross-coupled filter. All the theoretical analysis and design procedures have been successfully verified by experiment results.

Technology-based electromagnetic education

Abstract: In this paper, we briefly review the various roles of technology in stimulating interest and deepening understanding of abstract and highly mathematical subjects such as electromagnetics (EM). The general advantages of using technology in offering Web-based courses and professional training are described and examples of the ongoing activities in this area are summarized. Focus, however, is placed on the development and effective use of multimedia assets in the modern teaching of fundamental EM and more advanced microwave courses. Development and use of interactive components such as virtual laboratories, virtual instruments, simulation software, animation, and virtual participation in practical applications are described. The new "Conceptual Learning of Engineering" project is also described, and examples demonstrating the various ongoing activities are presented.

Low-loss compact Butler matrix for a microstrip antenna

Abstract: This paper presents the design and realization of a double four-port Butler matrix to feed a four-column array antenna with two orthogonally polarized signals (to obtain polarization diversity). The main goals of this study are the reduction of the size and the losses of the network. In order to meet those requirements, a bi-layer structure, the suspended stripline, has been adopted to support the circuit. Moreover, the complete network has been integrated in a single unit. The double four-port Butler matrix has been etched on both sides of the suspended substrate to solve the problem of the cross between the lines. The broadside suspended 3-dB directional coupler has been chosen for the design of the 3-dB hybrid coupler. In order to change the side of the suspended substrate, contactless transitions have been used. The network is designed to work within the range of frequencies of the GSM-900-MHz standard: band 880 MHz-960 MHz, center frequency f/sub 0/=920 MHz. Measured losses for a 4/spl times/4 Butler matrix are 0.3 dB.