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Microwave Theory and Techniques, IEEE Transactions on

Issue 11 • Date Nov. 2001

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Displaying Results 1 - 18 of 18
  • Guest editorial

    Page(s): 2065
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    Freely Available from IEEE
  • Packaging using microelectromechanical technologies and planar components

    Page(s): 2099 - 2104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (225 KB) |  | HTML iconHTML  

    A novel millimeter-wave packaging structure was developed in which a micromachined low-loss planar component and flip-chip devices were integrated on a silicon substrate. A low-loss planar filter was achieved on a 7-mm-square silicon substrate employing an inverted microstrip line and a unique resonator. High attenuation in the stopband was also obtained by introducing a pole control technique. Fabrication of a compact K-band receiver front-end incorporating a built-in filter was realized using multilayered benzocyclobutene (BCB) and flip-chip bonding techniques. Furthermore, we propose an alternative BCB suspended structure and demonstrate a planar antenna for Ka-band applications. These technologies bring to reality high-performance compact packaged systems in millimeter-wave region applications View full abstract»

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  • Ultra-low-noise indium-phosphide MMIC amplifiers for 85-115 GHz

    Page(s): 2080 - 2085
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (217 KB) |  | HTML iconHTML  

    This paper describes a high-performance indium-phosphide monolithic microwave integrated circuit (MMIC) amplifier, which has been developed for cooled application in ultra-low-noise imaging-array receivers. At 300 K, the four-stage amplifier exhibits more than 15-dB gain and better than 10-dB input and output return loss from 80 to 110 GHz. The room-temperature noise figure is typically 3.2 dB, measured between 90-98 GHz. When cooled to 15 K, the gain increases to more than 18 dB and the noise figure decreases to 0.5 dB. Only one design pass was required to obtain very good agreement between the predicted and measured characteristics of the circuit. The overall amplifier performance is comparable to the best ever reported for MMIC amplifiers in this frequency band View full abstract»

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  • MMIC development for millimeter-wave space application

    Page(s): 2073 - 2079
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB) |  | HTML iconHTML  

    The latest millimeter-wave monolithic-microwave integrated-circuit (MMIC) developments and technologies at the Mitsubishi Electric Corporation, Kanagawa, Japan, concerning high power amplifiers, low-noise amplifiers and phase shifters have been summarized. It has been shown that high-efficiency, low-noise, and low-loss performance for millimeter-wave space applications can be achieved by employing pseudomorphic high electron-mobility transistor (p-HEMT) MMIC technology. The investigation for gamma-ray irradiation hardness has cleared that millimeter wave p-HEMT MMICs have over a 100 years of life against gamma-ray irradiation in the space environment View full abstract»

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  • Measurement and characterization of HEMT dynamics

    Page(s): 2105 - 2111
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (191 KB) |  | HTML iconHTML  

    The variation of high electron-mobility transistor (HEMT) large-signal behavior with a change in operating condition is examined with a view to understanding the dynamics involved and developing a modeling strategy. The observed variation exhibits the dynamics of thermal, impact ionization, and trapping effects. A novel measurement of drain characteristic transients gives time-evolution information that clearly shows these as separate quantifiable phenomena with significant dependence on initial operating conditions. A drain-current model that describes high-frequency characteristics with pinchoff, gain, and drain feedback parameters is adapted to describe the variation of the characteristics with changing operating conditions. The results reported give insight and grounding for simulation of HEMT circuits View full abstract»

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  • Self-assembling MEMS variable and fixed RF inductors

    Page(s): 2093 - 2098
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (142 KB) |  | HTML iconHTML  

    Inductors play a key role in wireless front-end circuitry, yet are not generally well suited for conventional RF integrated-circuit (RFIC) fabrication processes. We have developed inductors that can be fabricated on a conventional RFIC silicon substrate, which use warping members to assemble themselves away from the substrate to improve quality factor (Q) and self-resonance frequency (SRF), and to provide a degree of variation in inductance value. These self-assembling variable inductors are realized through foundry provided microelectromechanical systems (MEMS) processing and have demonstrated temperature stable Q values greater than 13, SRF values well above 15 GHz, and inductance variations greater than 18%. Simulations suggest the potential for Q values above 20 and inductance variations greater than 30%, with optimized processing View full abstract»

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  • Modal analysis of waveguide antennas with arbitrary cross sections

    Page(s): 2152 - 2156
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (142 KB) |  | HTML iconHTML  

    An approach is given to analyze the modal coupling of open-ended waveguides with arbitrary cross sections located in a conducting screen. The presented theory enables the determination of reflection characteristics of a single waveguide, as well as the analysis of mutual coupling between elements in waveguide antenna arrays. The field inside each waveguide is expressed as a sum of the transverse-electric and transverse-magnetic modes and expressions for the mutual admittances of modes excited at the aperture are obtained using a direct integration method. From these expressions, the mode reflection and conversion coefficients are determined. Computed and measured results are presented. Furthermore, this approach has been used to design a new type of horn antenna with high return loss and equal radiation patterns in the two principle planes View full abstract»

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  • Size-reduction techniques for CPW and ACPS structures

    Page(s): 2112 - 2116
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    In coplanar-waveguide technology, there is a possibility of locating shunt and series matching stubs inside the center conductor of the transmission line. This principle can be used to reduce of the dimensions of microwave components such as monolithic microwave integrated circuits. This paper discusses the concept and presents the design of a reduced-size Wilkinson divider based on the realization of short-circuit series stubs in the signal conductor of an asymmetric coplanar stripline View full abstract»

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  • Maximizing signal strength for OFDM inside buildings

    Page(s): 2131 - 2136
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB) |  | HTML iconHTML  

    Propagation inside buildings suffer from large shadowing and high multipath effects. This is a serious problem for wireless local area network (WLAN) systems. This paper shows that shadowing and path loss can be minimized by exploiting the multipath tolerance of orthogonal frequency-division multiplexing (OFDM). This can be achieved by using multiple transmission antennas spread over the area of a WLAN cell. These antennas act as repeaters, transmitting and receiving the same signal at the same time. This decreases the average path loss, but increases the multipath delay spread. Using OFDM allows the advantage of reduced path loss to be utilized without detrimental effects of inter-symbol interference caused by the increased delay spread. The reduced path loss allows an increased system capacity, quality of service, or a decrease in intercellular interference in a cellular WLAN View full abstract»

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  • Automated computer-controlled tuning of waveguide filters using adaptive network models

    Page(s): 2125 - 2130
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    This paper describes a method for computer-controlled tuning of waveguide filters. The tuning algorithm is based on approximate filter network models, which take into account the effects of input/output coupling. Based on measurements of an initial filter design, the approximate network model is then corrected by optimizing the element values such that they minimize the mean square error between the measured and simulated response. The sensitivities of the tuning screws are determined directly from the sensitivities of the element values. Filter tuning is accomplished by gradient optimization of the corrected computer model rather than its physical realization. Only as a final step are the tuning screws of the physical model turned to the position determined by the optimization process View full abstract»

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  • Synergistic design of DSP and power amplifiers for wireless communications

    Page(s): 2163 - 2169
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (126 KB) |  | HTML iconHTML  

    Co-design of digital signal-processing (DSP) algorithms and power-amplifier characteristics can lead to improved efficiency and linearity through a variety of strategies including: predistortion, DSP control over bias conditions, particularly the power supply voltage, and DSP generation of digital input signals for switching amplifiers. This paper discusses several amplifier architectures that exemplify these approaches, including: bias-controlled amplifiers, linear amplification with nonlinear component amplifiers, and class-S amplifiers. We envision for the future a generation of “smart power amplifiers,” in which DSP optimization of amplifier parameters is carried out for changing environments View full abstract»

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  • Do we really need ferroelectrics in paraelectric phase only in electrically controlled microwave devices?

    Page(s): 2117 - 2124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (166 KB) |  | HTML iconHTML  

    Typical paraelectric materials (e.g., SrTiO3, KTaO3, BaxSr1-xTiO3, x<0.5) and electrically tunable microwave devices based on these materials are briefly reviewed. The analysis shows that in spite of the recent year's extensive efforts, no considerable improvement in the microwave losses in thin paraelectric films has been achieved. Thin films, regardless of fabrication method and substrate type, have much lower dielectric permittivity than bulk single crystals, and the loss tangent at microwave frequencies (f>10 GHz) is of the order of 0.01 (at zero dc-bias field) at room temperature. Nevertheless, quite promising component and subsystem level devices are successfully demonstrated. Use of ceramic (bulk and thick film) ferroelectrics in tunable microwave devices, currently considered for industrial applications, offer cost reduction. In this paper, explicitly for the first time, we consider possibilities and benefits of using ferroelectrics in polar phase in electrically controllable microwave devices. Examples of using ferroelectrics in polar state (e.g., Na0.5K0.5NbO3, SrTiO3 in antiferroelectric phase) in electrically tunable devices are reported View full abstract»

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  • An iterative FEM for scattering by a 3-D cavity-backed aperture

    Page(s): 2147 - 2151
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (141 KB) |  | HTML iconHTML  

    A finite-element method (FEM)-based hybrid method (or iterative FEM) is successfully applied to a three-dimensional (3-D) scattering problem without the effect of internal resonance. With only a small number of meshes around a 3-D scatterer, this FEM is shown to give an accurate result through several iterative updates of the boundary conditions. To confirm the efficiency of this method, scattering from a 3-D cavity-backed aperture is analyzed and the results obtained are compared with the same obtained by another conventional method View full abstract»

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  • Design and characterization of a 120-GHz millimeter-wave antenna for integrated photonic transmitters

    Page(s): 2157 - 2162
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (243 KB) |  | HTML iconHTML  

    We developed a planar slot antenna on an Si substrate for a photonic >100-GHz millimeter-wave (MMW) transmitter. We designed the antenna by using three-dimensional electromagnetic-field simulators and characterized its performance by using an optoelectronic network analyzer. The transmitter uses a very fast photodiode with high output power. Using these photonic techniques, we succeeded in building this compact photonic transmitter that emits MMWs with a power of >0.2 mW at a frequency of 120 GHz View full abstract»

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  • Performance analysis of smart antenna test-bed operating in a wide-band CDMA channel

    Page(s): 2142 - 2146
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (134 KB) |  | HTML iconHTML  

    In this paper, we present a performance analysis of a smart antenna system operating in a wide-band CDMA wireless-local-loop channel using a beam-forming module (BFM) that has been implemented on a digital signal processor (TMS320C6701) board. We first show the results of computer simulations obtained from the modeled received (RX) signals through a test-bed system consisting solely of baseband signal processing parts, i.e., modeled RX data-generating PC, BFM for computing the optimal weight vector and interfacing module. A test-bed system of the entire base station is then implemented to evaluate the adaptive beam-forming function with the actual wireless signals. This test-bed system includes several subscribers, as well as the array antenna, RF modules, and other receiving parts required at the cell site View full abstract»

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  • Analog MMICs for millimeter-wave applications based on a commercial 0.14-μm pHEMT technology

    Page(s): 2086 - 2092
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    This paper describes recent results obtained from the monolithic-microwave integrated-circuit design activity at Chalmers University, Goteborg, Sweden. The goal is to design all circuits needed for the front end of a 60-GHz wireless local area network and to build various system demonstrators. Some recent experimental results from this activity like different 60-GHz amplifiers, a general-purpose IF amplifier, a 60-GHz resistive mixer, and frequency multipliers are reported in this paper. Parameters such as the gain, conversion loss, noise figure, dc-power dissipation, as well as the model used in the simulations are reported and discussed View full abstract»

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  • K-band and millimeter-wave MMICs for emerging commercial wireless applications

    Page(s): 2066 - 2072
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (412 KB) |  | HTML iconHTML  

    The recent K-band monolithic-microwave integrated-circuit (MMIC) technologies for the local multipoint distribution service systems and novel MMIC technologies for potential low-cost millimeter-wave MMICs are presented in this paper via a review of Fujitsu Quantum Devices Limited technology. The devices being demonstrated are a 23-26-GHz 2-W power amplifier module with a broad-band driver amplifier, a 19-33-GHz miniature low-noise amplifier, a frequency multiplier by four for K-band local oscillators, a flip-chip MMIC module for radar application, and three-dimensional MMIC image-rejection harmonic mixers. Through these devices, the recent trend of design and fabrication methodologies for the K-band and millimeter-wave devices will be described View full abstract»

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  • Constant flux illumination of square cells for millimeter-wave wireless communications

    Page(s): 2137 - 2141
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (154 KB) |  | HTML iconHTML  

    The use of highly shaped-beam base-station antennas in millimeter-wave wireless communication systems may contribute to significantly enhance system performance. Previously proposed axial symmetric dielectric lenses provide a most useful constant-flux circular footprint, but they may fail to cover the regions near the vertices of square or rectangular cells, unless excessive wall illumination is allowed. This paper presents a simplified procedure to design shaped three-dimensional dielectric lenses that produce constant-flux illumination with square or rectangular footprints, suitable for indoor cells. The procedure is based on circular symmetric dielectric-lens design formulation, yet very sharp rectangular-cell boundary is obtained. Calculated and measured antenna performance is presented, not only in terms of radiation pattern, but also in terms of coverage and time-dispersion characteristic. The procedure is demonstrated for a square-cell lens and is extended for the rectangular-cell case View full abstract»

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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
Dominique.Schreurs@ieee.org

Editor-in-Chief
Jenshan Lin
jenshan@ieee.org