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Microwave Theory and Techniques, IEEE Transactions on

Issue 11  Part 2 • Date Nov 1998

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Displaying Results 1 - 18 of 18
  • Thin frequency-selective lattices integrated in novel compact MIC, MMIC, and PCA architectures

    Page(s): 1936 - 1948
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    We analyze and optimize the design of novel composite materials for ICs and printed circuit antenna (PCA) applications. We are using a variety of finite artificial lattices (FALs) carrying passive metalo-dielectric unit cells. We first examine and optimize these lattices as freestanding structures, regarding them as FSSs and space filters. We obtain several designs for appropriate metalo-dielectric unit cells, as well as stacking geometries for constructing thin laterally infinite artificial lattices. Further, we examine the action of the corresponding FAL within integrated architectures, emphasizing crosstalk suppression, circuit-coupling tailoring, and gain enhancement. We find very significant directive gain enhancements for compact packaged PCA applications. Finally, anomalous scaling of the resulting circuits and tunable designs are also presented View full abstract»

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  • A terahertz grid frequency doubler

    Page(s): 1976 - 1981
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    We present a 144-element terahertz quasi-optical grid frequency doubler. The grid is a planar structure with bow-tie antennas as a unit cell, each loaded with a planar Schottky diode. The maximum output power measured for this grid is 24 mW at 1 THz for 3.1-μs 500-GHz input pulses with a peak input power of 47 W. An efficiency of 0.17% for an input power of 6.3 W and output power of 10.8 mW is measured. To date, this is the largest recorded output power for a multiplier at terahertz frequencies. Input and output tuning curves are presented and an output pattern is measured and compared to theory View full abstract»

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  • Progress in active integrated antennas and their applications

    Page(s): 1891 - 1900
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    Active integrated antennas (AIAs) provide a new paradigm for designing modern microwave and millimeter-wave architecture with desirable features such as compactness, light weight, low cost, low profile, minimum power consumption, and multiple functionality. This paper reviews recent research and development related to this emerging technology with emphasis on its applications in high-efficiency radio-frequency (RF) front-end, millimeter-wave power combining, beam steering, and retrodirective arrays, as well as wireless sensors. Optical controlling techniques for AIA's are also described View full abstract»

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  • Distributed MEMS true-time delay phase shifters and wide-band switches

    Page(s): 1881 - 1890
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    Wide-band switches and true-time delay (TTD) phase shifters have been developed using distributed microelectromechanical system (MEMS) transmission lines for applications in phased-array and communication systems. The design consists of a coplanar waveguide (CPW) transmission line (W=G=100 μm) fabricated on a 500 μm quartz substrate with fixed-fixed beam MEMS bridge capacitors placed periodically over the transmission line, thus creating a slow-wave structure. A single analog control voltage applied to the center conductor of the CPW line can vary the phase velocity of the loaded line by pulling down on the MEMS bridges to increase the distributed capacitive loading. The resulting change in the phase velocity yields a TTD phase shift. Alternatively, the control voltage can be increased beyond the pull-down voltage of the MEMS bridges such that the capacitive loading greatly increases and shorts the line to ground. The measured results demonstrate 0-60 GHz TTD phase shifters with 2 dB loss/118° phase shift at 60 GHz (~4.5-ps TTD) and 1.8 dB loss/84° phase shift at 40 GHz. Also, switches have been demonstrated with an isolation of better than 40 dB from 21 to 40 and 40 to 60 GHz. In addition, a transmission-line model has been developed, which results in very close agreement with the measured data for both the phase shifters and switches. The pull-down voltage is 10-23 V, depending on the residual stress in the MEMS bridge. To our knowledge, this paper presents the first wide-band TTD MEMS phase shifters and wide-band switches to date View full abstract»

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  • Micromachining for terahertz applications

    Page(s): 1821 - 1831
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    An overview of recent progress in the research and development of micromachined antennas, transmission lines, waveguides structures, and planar movable components for terahertz frequencies is presented. Micromachining is shown to provide a low-cost alternative to conventional (and very expensive) machined-waveguide technology, resulting in antennas with excellent radiation patterns, low-loss tuners, and three-dimensional (3-D) micromachined structures suitable for terahertz applications. Fabrication procedures for a variety of micromachined waveguide and planar structures are described here, along with measured terahertz performance. Applications of micromachining techniques for terahertz systems include focal-plane imaging arrays requiring a large number of elements and low-cost receivers for commercial and industrial applications such as pollution monitoring View full abstract»

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  • Microtechnology in the development of three-dimensional circuits

    Page(s): 1832 - 1844
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    With today's cost-conscience industry, low cost, high-performance, and high-profit microwave-circuit technologies are essential. To increase density and reduce size and cost, the integration of analog and digital circuits on one single chip is considered the most viable solution. In reducing the size of the overall system, high-density integration (HDI) and packaging have become critical components in circuit design. This paper reviews and evaluates state-of-the-art planar transmission lines and vertical interconnects for use in high-density multilayer circuits for silicon- and SiGe-based monolithic high-frequency circuits. Packaging issues associated with parasitics are discussed and examples of multilayer three-dimensional systems utilizing micromachining are presented View full abstract»

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  • A 10-60-GHz micromachined directional coupler

    Page(s): 1845 - 1849
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    A 20-dB directional coupler has been designed and fabricated on a thin dielectric membrane using micromachining techniques. The fabrication process is compatible with monolithic microwave integrated-circuit (MMIC) techniques, and the coupler can be integrated into a planar-circuit layout. Design of the asymmetric tapered coupled-line coupler relies on simple quasi-static models and ideal transmission-line theory. The use of membrane technology results in less than 0.5-dB insertion loss in the coupler from 10 to 60 GHz. In addition, a micromachined packaging technique creates a shielded circuit, which is extremely compact and lightweight View full abstract»

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  • Microwave phase conjugation using antenna arrays

    Page(s): 1910 - 1919
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    A technique has been developed and tested for achieving phase conjugation in the microwave and millimeter-wave regime. The effective nonlinearity required for this phase-conjugation process is provided by electronic mixing elements feeding an array of antennas. Using these balanced mixing circuits in conjunction with a one-dimensional array antenna, we have demonstrated two-dimensional free-space phase conjugation at 10.24 GHz. A critical factor of this technique is the delivery of a 2ω pump signal to each array element with the same phase. Two types of interconnects, electrical and a more versatile optical technique, have been implemented to distribute the pump signal in our demonstrations. In both systems, two-dimensional free-space phase conjugation was observed and verified by directly measuring the electric-field amplitude and phase distribution under various conditions. The electric-field wave-fronts exhibited retro-directivity and the auto-correction characteristics of phase conjugation. Furthermore, these experiments have shown amplified conjugate-wave power up to ten times of that of the incoming wave. This amplifying ability demonstrates the potential of such arrays to be used in novel communications applications View full abstract»

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  • Integration of air-gap transmission lines on doped silicon substrates using glass microbump bonding techniques

    Page(s): 1850 - 1855
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    Air-gap transmission-line structures have been fabricated and integrated on doped silicon substrates using glass microbump bonding (GMBB) techniques. The air-gap transmission lines have the advantages of low losses and low dispersion compared to conventional uniplanar transmission lines on semiconductor substrate. This bonding technique provides an alternative approach for both monolithic microwave integrated circuits (MMICs) and optoelectronic integrated circuits (OEICs) on silicon substrates. To demonstrate the potential of air-gap structures, several transmission-line configurations are fabricated and tested. The measured data are compared with simulation results. The results confirm the air-gap structures low-loss capabilities. To further explore the advantage of this bonding technique, several spiral inductors are fabricated in air-gap configurations. Their measured characteristics demonstrate the low dispersion potential of this technology. Finally, the integration of air-gap interconnects for OEICs on silicon CMOS circuitry is also proposed View full abstract»

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  • Properties of periodic arrays of symmetric complementary structures and their application to grid amplifiers

    Page(s): 1956 - 1963
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    Deschamps' theorem for n-terminal complementary structures is reviewed. An extension to Deschamps' theorem for a class of three-terminal bounded structures with one axis of symmetry is presented. It is shown that, for these structures, a simple relationship between the impedances of the odd mode of the original structure and the admittances of the even mode of the complementary structure exists, and that these modes are orthogonal. Using this, a self-complementary grid amplifier is designed and the measured results are presented View full abstract»

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  • Optimized irregular structures for spatial- and temporal-field transformation

    Page(s): 1856 - 1867
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    In a bounded region such as a waveguide, a mode is an eigensolution of the electromagnetic-wave equation with particular boundary conditions imposed. Conversion from one mode to another through a mode converter could be accomplished by using a scatterer located within the waveguide. Generalizing to an arbitrary domain, either within a waveguide or in unbounded media, a field transformer converts one spatial field to another as a function of frequency. Mode-control elements usually employ periodic structures and a special case of this mode conversion is filtering (amplitude and phase control) with the same input and output mode. We have developed a new kind of field transformer which uses aperiodic structures. Specific designs are arrived at through numerical optimization of a cost function representing the mode transformation. Rather than effecting field transformations using a series of small geometry perturbations, our concept forcefully changes the field using an optimized structure. The optimization process allows consideration of a number of electrical and mechanical issues, such as efficiency, bandwidth, size, and amenability to manufacture. We present designs for microwave mode converters using our optimized irregular structure concept and compare them with those achieved using a periodic coupled-mode concept. These designs show dramatic improvements in performance and physical size, while incorporating a dimensional constraint and sensitivity analysis that provides for ease in fabrication View full abstract»

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  • Voltage-controlled biphase attenuator and vector synthesizer for monolithic microwave signal processors

    Page(s): 1982 - 1985
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    A GaAs monolithic voltage-controlled biphase attenuator and a vector synthesizer, which utilize remote-pinchoff cold field-effect transistors (RePOFETs), are newly developed for microwave signal-processor applications. Their features are very small circuit size, which permits dense integration, and high control linearity. Lumped-constant topologies and internal impedance optimization successfully reduce the sizes of the attenuator and vector synthesizer to just 0.5 and 2.1 mm2 respectively. The control sensitivity deviation exhibited is within ±5% for over 50% of the full control range. The uniformity of the measured vector constellation is also improved by the RePOFETs View full abstract»

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  • Novel beam-control techniques using dielectric-image-line-fed microstrip patch-antenna arrays for millimeter-wave applications

    Page(s): 1930 - 1935
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    This paper reports novel beam-control methods which have the potential of low cost and simplicity. The beam direction of the antenna array is controlled by changing the distance between the perturbed dielectric image line (DIL) and a movable reflector plate. A rigorous hybrid-mode theoretical analysis is developed for calculating the dispersion of propagation constants in DILs without or with the movable reflector plate and, then, for designing beam-control patch-antenna arrays. Experimental results of scanning angles agree well with theoretical predictions at Ka-band frequencies View full abstract»

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  • Novel architectures for high-efficiency amplifiers for wireless applications

    Page(s): 1901 - 1909
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    This paper presents three novel architectures for high-efficiency amplifiers relying on new harmonic-tuning techniques. These methods yield high-efficiency power amplifiers and reduce unwanted harmonic radiation from the transmitter front end. The first method uses the active integrated-antenna approach to perform harmonic tuning. The second method uses a nontraditional periodic microstrip filter, which allows broadband harmonic tuning. Finally, the third method combines the previous two approaches. Each technique is illustrated by a design example of a power amplifier integrated with an antenna. Guidelines for choosing the appropriate antenna structure and for designing the periodic structures are also presented. Another design issue is inclusion of the antenna and/or periodic structures into the amplifier simulation. To do this, a hybrid approach combining the finite-difference time-domain (FDTD) analysis and harmonic-balance simulation is employed View full abstract»

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  • Injection- and phase-locking techniques for beam control [antenna arrays]

    Page(s): 1920 - 1929
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    Applications of millimeter-wave radar, imaging, and communication technology requires cost-effective implementation of intelligent scanning antenna systems. Injection-locking and phase-locked-loop (PLL) techniques can be used to achieve synchronous operation of a number of antenna array elements, and allow for the manipulation of the phase distribution without additional phase-shifting circuitry, suggesting a potential for low-cost beam-scanning systems. This paper describes a number of techniques, with an assessment of some remaining technical challenges for practical implementation View full abstract»

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  • Quasi-optical transmit/receive front ends

    Page(s): 1964 - 1975
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    Quasi-optical (QO) active circuits have originally received interest for power generation by large-scale power combining of solid-state devices at microwave and millimeter-wave frequencies. Here, we present an overview of QO components developed with functionality in mind, with an emphasis on bidirectional amplifier arrays for transmit/receive (T/R) front ends. We discuss possible advantages of the QO architecture for communications and radar. The following three QO bidirectional arrays are presented: 1) a nine-element X-band patch antenna array with different polarizations in T/R modes; 2) a 24-element X-band slot lens array with switches for the T/R paths; and 3) a 22-element Kα-band patch lens array using monolithic microwave integrated circuits (MMICs) View full abstract»

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  • RF-MEMS switches for reconfigurable integrated circuits

    Page(s): 1868 - 1880
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    This paper deals with a relatively new area of radio-frequency (RF) technology based on microelectro-mechanical systems (MEMS). RF MEMS provides a class of new devices and components which display superior high-frequency performance relative to conventional (usually semiconductor) devices, and which enable new system capabilities. In addition, MEMS devices are designed and fabricated by techniques similar to those of very large-scale integration, and can be manufactured by traditional batch-processing methods. In this paper, the only device addressed is the electrostatic microswitch - perhaps the paradigm RF-MEMS device. Through its superior performance characteristics, the microswitch is being developed in a number of existing circuits and systems, including radio front-ends, capacitor banks, and time-delay networks. The superior performance combined with ultra-low-power dissipation and large-scale integration should enable new system functionality as well. Two possibilities addressed here are quasi-optical beam steering and electrically reconfigurable antennas View full abstract»

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  • Element efficiency and noise in grid arrays

    Page(s): 1949 - 1955
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    The element efficiency of a phased array is the ratio of the radiated-to-available power of a single element, when only that element is excited. We relate this element efficiency to the output noise power generated by a quasi-optical grid amplifier array. Both electromagnetic and thermodynamic derivations are presented. These ideas are used to predict the total noise power and noise radiation pattern of grid arrays. The results are also extended to show that the output noise temperature of the entire array will be the same as the output noise temperature of a single element View full abstract»

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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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