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Microwave and Wireless Components Letters, IEEE

Issue 8 • Date Aug. 2001

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Displaying Results 1 - 11 of 11
  • 80 GHz MMIC HEMT VCO

    Page(s): 325 - 327
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (52 KB) |  | HTML iconHTML  

    In this letter a monolithic voltage-controlled oscillator (VCO) operating in the 77.5-83.5 GHz range is presented. InP HEMTs are used for both the active device and varactor. The VCO demonstrated a tuning range of 6 GHz and an output power better than 12.5 dBm in the entire tuning range. View full abstract»

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  • Compact low-loss monolithic CPW filters using air-gap overlay structures

    Page(s): 328 - 330
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (82 KB) |  | HTML iconHTML  

    In this letter, two types of compact low-loss monolithic coplanar waveguide (CPW) filters using air-gap overlay structures are presented. Vertical stacking in overlay structures offers size reduction. Furthermore, air-gap overlay structures do not require additional dielectric process and are free from dielectric losses. An X-band bandpass filter using air-gap overlaid artificial transmission lines showed 67% size reduction. A stepped-impedance low-pass filter using highly separated metal-air-metal (MAM) capacitors as low-impedance lines achieved not only size but also loss reduction. Small size, low loss, and simple process steps make the air-gap overlay structures very promising for monolithic CPW passive devices such as filters. View full abstract»

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  • Active antennas incorporating tunnel diodes-large signal model approach

    Page(s): 331 - 333
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (99 KB)  

    In this letter, a comprehensive dc and RF model of heterostructure interband tunnel diodes (HITDs) is extracted. Active antennas incorporating tunnel diodes are analyzed in the time domain using this tunnel diode model. The simulated and measured results are in good agreement in terms of oscillation frequencies of the active antennas. Phase noise of -114.67 dBc/Hz @1.0 MHz offset is achieved for injection-locked active antennas. The simulated injection locking range of a Ka band active antenna array is investigated. View full abstract»

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  • Inline capacitive and DC-contact MEMS shunt switches

    Page(s): 334 - 336
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (76 KB) |  | HTML iconHTML  

    This paper presents inline capacitive MEMS shunt switches suitable for X/K-band and Ka/V-band applications. The inline switch allows for a low- or high-inductance connection to the ground plane without changing the mechanical characteristics of the MEMS bridge. Excellent isolation and loss are achieved with this design, and the performance is very similar to the standard capacitive MEMS shunt switch. Also, a new metal-to-metal contact MEMS shunt switch is presented. A novel pull-down electrode is used which applies the electrostatic force at the same location as the metal-to-metal contact area. A contact resistance of 0.15-0.35 /spl Omega/ is repeatable, and results in an isolation of -40 dB at 0.1-3 GHz. The measured isolation is still better than -20 dB at 40 GHz. The application areas are in high-isolation/low-loss switches for telecommunication and radar systems. View full abstract»

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  • New nonlinear design tools for self-oscillating mixers

    Page(s): 337 - 339
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (81 KB) |  | HTML iconHTML  

    New nonlinear design tools for self-oscillating mixers are presented here, with the aim to increase the designer's control over their behavior. The new tools enable fixing the self-oscillation frequency and selecting the optimum self-oscillation amplitude for maximum conversion gain. They can also be applied for the optimized design of harmonic self-oscillating mixers. Using bifurcation-theory concepts, it has been possible to increase the input-power range with self-oscillating-mixer operation. A self-oscillating mixer with 5.5 GHz input frequency has been designed and simulated obtaining very good agreement with the experimental results. View full abstract»

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  • A millimeter-wave six-port reflectometer based on the sampled-transmission line architecture

    Page(s): 340 - 342
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (73 KB) |  | HTML iconHTML  

    This letter presents a proof-of-concept implementation of a millimeter-wave reflectometer for measuring complex reflection coefficients. The reflectometer is based on the six-port architecture and consists of a single section of WR-10 rectangular waveguide and a set of three Schottky power detectors. Design considerations as well as measurements in the 75 to 110 GHz range are described and discussed. Because of its simple architecture, the reflectometer is amenable to scaling for measurements well into the submillimeter-wave region of the spectrum. View full abstract»

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  • Difference pattern beam steering of coupled, nonlinear oscillator arrays

    Page(s): 343 - 345
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (65 KB)  

    In this letter, it is shown how to extend York's phase-shifterless beam steering technique to difference pattern scanning for monopulse applications. By making a simple modification to the coupling between the central elements of a one-dimensional array, the effective equivalence of the steered sum and difference problems is established. View full abstract»

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  • Leaky coaxial cable with adjustable coupling loss for mobile communications in complex environments

    Page(s): 346 - 348
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (75 KB) |  | HTML iconHTML  

    A new kind of leaky coaxial cable composed of an axially-slotted line covered with periodic metallic patches is proposed. The basic cable sets up a surface wave and does not radiate itself, but excites the patch apertures into radiation. The direction of the radiation field can be changed by adjusting the size and period of the patches according to the environmental application. A combined method that involves FDTD iteration and integration of the equivalent surface magnetic current is introduced in order to determine the radiation field accurately. View full abstract»

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  • An unconditionally stable 3-D ADI-MRTD method free of the CFL stability condition

    Page(s): 349 - 351
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (79 KB) |  | HTML iconHTML  

    In this paper, an alternating direction implicit (ADI) technique is applied to the recently developed multiresolution time-domain (MRTD) method, resulting in an unconditionally stable ADI-MRTD scheme free of the Courant-Friedich-Lecy (CFL) stability condition. The unconditional stability is theoretically proved, and preliminary numerical results are presented to validate the scheme. Because the scheme is now free of the stability condition, its time step is determined only by modeling accuracy. The price for having the unconditional stability is, however, that the required computation memory becomes almost twice of that for the original MRTD. View full abstract»

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  • Modal MRTD approaches for the efficient analysis of waveguide discontinuities

    Page(s): 352 - 354
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (57 KB)  

    This paper, the multi-resolution time-domain (MRTD) technique is applied to the waveguide discontinuity problem for fast-scattering parameter computation. To improve the computational efficiency, both three-dimensional (3-D) waveguide regions, including discontinuities, and one dimensional (1-D) homogeneous waveguide region, terminated with the modal absorbing boundary condition (ABC), are simulated in the wavelet domain with the mode composition/expansion algorithm from the modal analysis. A WG-90 rectangular waveguide with a thick asymmetric iris is analyzed and the numerical results are compared with conventional finite-difference time-domain (FDTD) results and mode-matching results. View full abstract»

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  • Patent abstracts

    Page(s): 355 - 360
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    Freely Available from IEEE

Aims & Scope

The IEEE Microwave and Wireless Components Letters (MWCL) publishes three page papers that focus on microwave theory, techniques and applications as they relate to components, devices, circuits, biological effects, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals.

Full Aims & Scope