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Microwave Theory and Techniques, IEEE Transactions on

Issue 9  Part 1 • Date Sept. 2004

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  • Table of contents

    Page(s): c1 - c4
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  • IEEE Transactions on Microwave Theory and Techniques publication information

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  • Guest Editorial

    Page(s): 2085 - 2086
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  • Recent system applications of short-pulse ultra-wideband (UWB) technology

    Page(s): 2087 - 2104
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    Developed in the early 1960s, time-domain electromagnetics, the study of electromagnetic-wave propagation from a time-domain perspective, has given birth to a fascinating new technology, which today is commonly referred to as ultra-wideband (UWB). It has now been slightly more than 25 years since the 1978 seminal paper of Bennett and Ross, which summarized UWB's early applications. It thus seems appropriate, given the tremendous increase in interest in the technology since the Federal Communications Commission modified its Part 15 rules to accommodate UWB transmissions, to take a look at more recent system applications of this unique technology. This paper provides a brief historical perspective of UWB, discusses recent techniques for the generation and reception of short-pulse electromagnetic waveforms, and examines a number of recently developed UWB systems in the communications, radar, and precision-positioning fields. Finally, a brief assessment of future trends for the technology is provided. View full abstract»

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  • Ultra-wideband radar sensors for short-range vehicular applications

    Page(s): 2105 - 2122
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    The recent approval granted by the Federal Communications Commission (FCC) for the use of ultra-wideband signals for vehicular radar applications has provided a gateway for the introduction of these sensors in the commercial arena as early as 2004. However, the rules governing the allowable spectral occupancy create significant constraints on the sensors' operation. This is further complicated by the variety of applications that these sensors are being required to fulfill. A review of the motivation for the development of these sensors is followed by a discussion of the consequent implications for waveform design and limitations on system architecture. Other practical considerations such as available semiconductor technology, packaging, and assembly techniques are reviewed, and results are presented for conventional surface-mount plastic packages illustrating their usefulness in the greater than 20-GHz frequency range. Suitable antenna technology for wide-band transmission is presented that is compliant with the specific restrictions stipulated in the FCC ruling. Finally, all of these considerations are combined with the presentation of a compatible integrated-circuit-based transceiver architecture. Measured results are presented for several critical circuit components including a +12-dBm driver amplifier for the transmitter, an RF pulse generator that can produce sub-1-ns pulses at a carrier frequency of 24 GHz, and a single-chip homodyne in-phase/quadrature down-conversion receiver that has a cascaded noise figure of less than 7 dB. All circuit components are fabricated in SiGe. View full abstract»

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  • Design of a multiband OFDM system for realistic UWB channel environments

    Page(s): 2123 - 2138
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    In February 2002, the Federal Communications Commission allocated 7500 MHz of spectrum for unlicensed use of commercial ultra-wideband (UWB) communication devices. This spectral allocation has initiated an extremely productive activity for industry and academia. Wireless communications experts now consider UWB as available spectrum to be utilized with a variety of techniques, and not specifically related to the generation and detection of short RF pulses as in the past. There are many differences between real-world behavior of narrow-band and UWB systems. All wireless systems must be able to deal with the challenges of operating over a multipath propagation channel, where objects in the environment can cause multiple reflections to arrive at the receiver (RX). For narrow-band systems, these reflections will not be resolvable by the RX when the narrow-band system bandwidth is less than the coherence bandwidth of the channel. The large bandwidth of UWB waveforms, instead, significantly increases the ability of the RX to resolve the different reflections in the channel. The UWB channel model developed by the IEEE 802.15.3a standard body is described in this paper. For highly dispersive channels, an orthogonal frequency-division multiplexing (OFDM) RX is more efficient at capturing multipath energy than an equivalent single-carrier system using the same total bandwidth. OFDM systems possess additional desirable properties, such as high spectral efficiency, inherent resilience to narrow-band RF interference, and spectral flexibility, which is important because the regulatory rules for UWB devices have not been finalized throughout the entire world. This paper describes the design of a UWB system optimized for very high bit-rate, low-cost, and low-power wireless networks for personal computing (PC), consumer electronics (CE), and mobile applications. The system combines OFDM modulation technique with a multibanding approach, which divides the spectrum into several sub-bands, whose bandwidth is approximately 500 MHz. The system described in this paper has been selected by several key industry organizations [Mulitband OFDM Alliance, WiMedia, Wireless Universal Serial Bus (USB)] because of its very good technical characteristics for the diverse set of high performance- short-range applications that are eagerly anticipated for CE, PC, and mobile applications. View full abstract»

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  • A new adaptive predistortion technique using software-defined radio and DSP technologies suitable for base station 3G power amplifiers

    Page(s): 2139 - 2147
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    We present in this paper an advanced adaptive baseband/RF predistorter that integrates the concept of the software-defined radio technology into the power-amplifier (PA) linearization area. The linearizer performs an instantaneous characterization of the PA, using two digital receivers, in order to supply its instantaneous AM-AM and AM-PM curves. It then determines an inverse function that represents the best fit to the reciprocal of the PA behavior. Code-division multiple-access and third-generation standard signals applying different stress level on the PA are used to evaluate the performance of the linearizer. The system is validated using digital signal processing/RF co-simulation for a typical 44-dBm class-AB PA. To estimate the performance of the linearizer under realistic condition, experimental results have been carried out in open-loop condition, supported by a software-instruments connectivity, for a 20-W class-AB PA operating at 1.96 GHz. Results for different cases of standards signals reveal a significant reduction, in the order of 5 dB, in effective output power backoff. View full abstract»

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  • Ultrawide-band transitions and new microwave components using double-sided parallel-strip lines

    Page(s): 2148 - 2152
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    Double-sided parallel-strip lines have been used as a balanced transmission line to feed double-sided printed antennas or to fabricate microwave components such as balanced mixers. In this paper, ultrawide-band transitions from microstrip line to double-sided parallel-strip line are developed with 1-30-GHz bandwidth. New microwave components using double-sided parallel-strip lines are designed with good measured results. The double-sided parallel-strip line has an advantage of easy realization of low-impedance lines, which are important for many component designs. View full abstract»

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  • The effect of geometry on the noise characterization of SiGe HBTs and optimized device sizes for the design of low-noise amplifiers

    Page(s): 2153 - 2162
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    The impacts of various layout configuration and device dimensions on device performance are examined. The geometrical scaling issues including emitter length and emitter stripe-number scaling are used to shift simultaneously the optimum noise and optimum source impedance to a point that is close to 50 Ω. Via this method, not only is the optimal transistor size for low-noise applications obtained, but the matching network is simplified to reduce the losses of passive networks and the chip area. Based on experimental results, optimum SiGe HBTs and bias suitable for low-noise amplifiers (LNAs) are determined. Via the comparison of the state-of-the-art SiGe LNAs, it is confirmed that this method is effective to obtain better performances. Using the same method, the optimum device size at any bias and any frequency for low-noise applications can also be achieved. View full abstract»

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  • Highly accurate and real-time determination of resonant characteristics: complex linear regression of the transmission coefficient

    Page(s): 2163 - 2168
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    For measuring high-frequency properties of materials by resonant techniques, one needs to obtain the resonant characteristics of the resonator, i.e., the resonant frequency fR and the bandwidth of the resonance fB. For precise measurements, accurate and real-time determination of the resonant characteristics is required. We present a complex linear regression method, which contains only the linear square-fit algorithm, and is applicable to the complex transmission coefficient data S21(f) with arbitrary phase error. Numerical simulations and experimental data show very high accuracy and stability of this technique, when compared with the standard 3-dB method and the Lorentzian-fit method. The optimum frequency span of the measurement is found to be approximately 1.5fB, where fB is the bandwidth of the resonance. View full abstract»

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  • Load-impedance and bias-network dependence of power amplifier with second harmonic injection

    Page(s): 2169 - 2176
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    For the power amplifier (PA) used in code-division multiple-access cellular phones, the supply voltage is switched from around 1.5 to 3.5 V at the boundary transmission power of several decibels higher than 10 dBm using a DC-DC converter to improve operation efficiency. Recently, however, this boundary transmission power is being raised. We applied the second harmonic injection to reduce distortion and maximize the boundary transmission power under low supply voltage. This paper presents the design concept of the PA's load impedance and bias network with second harmonic injection using Volterra-series analysis. We also present a design of the final stage of the PA under low supply voltage and show that the final stage has a drain efficiency of 53% at an output power of 21 dBm. View full abstract»

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  • Microwave impedance control over a ferroelectric boundary layer

    Page(s): 2177 - 2182
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    Microwave far-field radiation was simulated using a coax cable inside which a ferroelectric layer with a ground plane was loaded. The ferroelectric layer was electrically biased via a planar permeable electrode allowing an RF electromagnetic field to penetrate, thereby causing reflection. By interpolating the normal-mode frequencies of the cavity resonator formed by the coax cable, it was determined the coupling between the loaded ferroelectric sample and the resonator is second order. An effective electric-bias configuration for a ferroelectric layer is thus proposed. View full abstract»

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  • Design and measurement of a bandpass filter at 300 GHz based on a highly efficient binary grating

    Page(s): 2183 - 2189
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB) |  | HTML iconHTML  

    A bandpass filter for 300 GHz with a stopband at 450 GHz based on a highly efficient binary grating as a frequency-selective element was developed and optimized. The geometry of the grating was carefully designed for a maximum difference angle between reflected beams at 300 and 450 GHz and for maximum efficiency at 300 GHz. The grating efficiency was optimized using a rigorous theory of diffraction, yielding a maximum efficiency of over 99.5% neglecting conductor losses. Antennas and elliptical mirrors are used for optimum quasi-optical illumination of the grating and Gaussian beam shaping. After an optimization and a comprehensive examination of the grating in an experimental heterodyne measurement setup at 300 GHz, the filter was implemented fixed tuned into a small housing with waveguide flanges. The fixed tuned setup with corrugated feed horns results in an overall flange-to-flange insertion loss of only 2.8 dB. View full abstract»

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  • IEEE Transactions on Microwave Theory and Techniques information for authors

    Page(s): 2193
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  • IEEE Microwave Theory and Techniques Society Information

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Aims & Scope

The IEEE Transactions on Microwave Theory and Techniques focuses on that part of engineering and theory associated with microwave/millimeter-wave components, devices, circuits, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals. This includes scientific, technical, and industrial, activities. Microwave theory and techniques relates to electromagnetic waves usually in the frequency region between a few MHz and a THz; other spectral regions and wave types are included within the scope of the Society whenever basic microwave theory and techniques can yield useful results. Generally, this occurs in the theory of wave propagation in structures with dimensions comparable to a wavelength, and in the related techniques for analysis and design..

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Editor-in-Chief
Dominique Schreurs
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Editor-in-Chief
Jenshan Lin
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