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Microwave and Wireless Components Letters, IEEE

Issue 8 • Date Aug. 2006

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  • Table of contents

    Page(s): c1
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  • IEEE Microwave and Wireless Components Letters publication information

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  • Z -Transform Implementation of the CFS-PML for Arbitrary Media

    Page(s): 437 - 439
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (133 KB) |  | HTML iconHTML  

    An efficient implementation of the complex frequency-shifted perfectly matched layer (CFS-PML) based on stretched coordinate PML (SC-PML) formulations and the Z-transform method is presented for truncating the finite-difference time domain (FDTD). This method is completely independent of the material properties of the FDTD computational domain and hence can be applied to the modeling of arbitrary media without any modification. A numerical test has been carried out in three dimensions to validate these formulations. It is shown that the proposed formulations with a CFS scheme are efficient in attenuating evanescent waves and reducing late-time reflections View full abstract»

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  • Capacitive-Ended Interdigital Coupled Lines for UWB Bandpass Filters With Improved Out-of-Band Performances

    Page(s): 440 - 442
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (459 KB) |  | HTML iconHTML  

    This letter presents a novel ultra-wideband (UWB) microstrip bandpass filter on a microstrip line with improved out-of-band performances. A multiple-mode resonator (MMR) is first constituted to equally allocate its first three resonant frequencies in the 3.1-10.6-GHz UWB band. Two capacitive-ended interdigital coupled lines are then formed to assign their transmission zero towards the fourth-order resonant frequency of this MMR, thereby suppressing the first spurious passband. Moreover, two outer arms in the interdigital lines are properly tapered to compensate the phase imbalance or group delay near the UWB upper-end relying on extra capacitive-ended stubs. And finally, two UWB filters with one- and two-MMRs are designed and implemented to experimentally demonstrate the improved out-of-band performances, i.e., widened/deepened upper-stopband and sharpened rejection skirts outside the UWB passband View full abstract»

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  • A Bandpass Filter Design Using Half-Wavelength Stepped Impedance Resonators With Internal Couplings

    Page(s): 443 - 445
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB) |  | HTML iconHTML  

    We propose a new type of microstrip half-wavelength (lambda/2) stepped impedance resonator (SIR) for use in bandpass filter (BPF) designs. This lambda/2 SIR has an internal coupling section that can be used to generate a coupling coefficient in the filter design in addition to couplings between SIRs. It also contains additional stepped impedance lines that shift and suppress the lowest even-mode resonance frequencies to more than what can be achieved by conventional lambda/2 SIRs. Moreover, a transmission zero is generated close to its fundamental resonance frequency (f0) which can be used in definition of the filter response. A fourth-order microstrip BPF with 10% bandwidth was constructed using two of the proposed lambda/2 SIRs with a stepped impedance ratio (R) of 0.528. The experimental result shows that the filter can achieve low in-band loss and out-of-band attenuation of 52.6dB up to 3f0. The lowest spurious resonance frequency is shifted to 3f0 as opposed to 2.5f0 in conventional lambda/2 SIRs with the same R value View full abstract»

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  • Modified Vertically Installed Planar Couplers for Ultrabroadband Multisection Quadrature Hybrid

    Page(s): 446 - 448
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (529 KB) |  | HTML iconHTML  

    In this letter, we describe a five-section ultrabroadband 1-9GHz microstrip quadrature hybrid (90deg, -3dB coupler), which uses two types of modified vertically installed planar (VIP) couplers and is suitable for conventional printed circuit board realization. The modified VIP couplers provide not only a way to implement tight coupling value with reduced modal phase velocity difference but also a layout flexibility to minimize the discontinuity between sections. An experimental circuit is designed and fabricated with a passband ripple of plusmn0.5dB, a return loss of less than -20dB, and an isolation of better than 20dB over the frequency of 1-9GHz. Very good agreement between the simulated and measured results is obtained View full abstract»

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  • A Novel Planar Three-Way Power Divider

    Page(s): 449 - 451
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB) |  | HTML iconHTML  

    A novel planar three-way power divider is proposed. Based on the conventional planar microstrip coupled line technology, the proposed three-way power divider can modify a three-way Wilkinson power divider from a three-dimensional configuration into a two-dimensional one, meanwhile, to keep the length of the circuit to be lambda/4. The planar structure enables easy circuit design in printed circuit boards and monolithic microwave integrated circuits. The design concept and implementation are discussed. From the measured results, less than 4.8plusmn0.1dB of the three equivalent insertion losses, less than 19.5dB of the return loss, and better than 17.5dB of isolation at 2.4GHz can be achieved View full abstract»

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  • Tri-Band Wilkinson Power Divider Using a Three-Section Transmission-Line Transformer

    Page(s): 452 - 454
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (658 KB) |  | HTML iconHTML  

    The analysis and design of a triple-band equal-split Wilkinson power divider are described. The circuit proposed is well matched and isolated at three arbitrary frequencies. The design procedure for the three-section transmission-line transformer based equal-split Wilkinson power divider derived from the ideal transmission-line model is provided. Simulated and experimental results in microstrip technology are presented to verify the idea and the derived equations View full abstract»

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  • A Novel TM _01 –TE _11 Circularly Polarized (CP) Mode Converter

    Page(s): 455 - 457
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (334 KB) |  | HTML iconHTML  

    A novel mode converter that converts a TM01 mode to a CP TE11 mode was developed. In the converter, the TM01 mode is transformed into a coaxial transverse electric and magnetic (TEM) mode first, then the coaxial TEM mode is split in space into multiple TE11 sector waveguide modes by eight plates in the coaxial waveguide, which further subject the TE11 sector waveguide modes to different signal paths and hence effectively convert the TEM mode into a CP TE11 mode. A mode converter at 4GHz was designed. The conversion efficiency of TM01-to-TE11 is 99% at center frequency with an axial ratio of 0.7dB. Over the frequency range of 3.8-4.3GHz, the conversion efficiency exceeds 90%, and the axial ratio is less than 2.7dB. A good agreement between experiments and simulations was observed View full abstract»

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  • LC-Notch-Filters Less Sensitive to LTCC Process Tolerances

    Page(s): 458 - 460
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (804 KB) |  | HTML iconHTML  

    A new design procedure for low temperature cofired ceramics integrated single inductance-capacitance (LC)-notch filters is described that minimizes the shift in resonance frequency due to process variations such as layer thickness and line-width variations. 25-mum thin layers of dielectric constant 7.8 and 17.9 were used for the experimental verification and further miniaturization of the layout. A two to five-fold reduction of the resonance frequency uncertainty was achieved compared to conventional designs. Application of these new single LC-notch filters in Bluetooth radio frequency-front-end modules is discussed View full abstract»

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  • Offset Cross-Slot-Coupled Dielectric Resonator Antenna for Circular Polarization

    Page(s): 461 - 463
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB) |  | HTML iconHTML  

    A cross-slot-coupled cylindrical dielectric resonator antenna (DRA) is studied theoretically and experimentally. In previous papers, a cross-slot of unequal slot lengths was centered under the dielectric resonator (DR), resulting in circular polarized operation of the antenna. In the present study, the design is enhanced by setting the centers of the two slots at different positions and taking into consideration the partial independence of the slot modes from the DRA mode. Thus, circular polarization (CP) bandwidth of up to 4.7% is attained experimentally in the broadside direction. It is also shown that a largely asymmetrical structure results in a very high bandwidth, but with the tradeoff of distorted CP operation off-broadside View full abstract»

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  • An Ultra-Low Noise Superconducting Antenna-Coupled Microbolometer With a Room-Temperature Read-Out

    Page(s): 464 - 466
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (441 KB) |  | HTML iconHTML  

    In this letter, we report the electrical and optical characteristics of a superconducting vacuum-bridge microbolometer with an electrical noise equivalent power of 26fW radicHz and an effective time constant of 380 ns, when operated at a bath temperature of 4K. We employ a novel room temperature external negative feedback readout architecture, that allows for noise matching to the device without bulky stepup transformers or cooled electronics. Both the detector and the readout lend themselves to be scaled to imaging arrays. The directly measured noise equivalent temperature difference over a 100-1000-GHz bandwidth is 125 mK in a 30-ms integration time View full abstract»

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  • A Novel 94-GHz MHEMT Resistive Mixer Using a Micromachined Ring Coupler

    Page(s): 467 - 469
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    In this letter, we present a high performance 94-GHz millimeter-wave monolithic integrated circuit resistive mixer using a 70-nm metamorphic high electron mobility transistor (MHEMT) and micromachined ring coupler. A novel three-dimensional structure of a resistive mixer was proposed in this work, and the ring coupler with the surface micromachined dielectric-supported air-gap microstrip line structure was used for high local oscillator/radio frequency (LO-RF) isolation. Also, the LO-RF isolation was optimized through the simulation. The fabricated mixer has excellent LO-RF isolation, greater than 29 dB, in 2-GHz bandwidth of 93-95GHz. The good conversion loss of 8.9dB was measured at 94GHz. To our knowledge, compared to previously reported W-band mixers, the proposed MHEMT-based resistive mixer using a micromachined ring coupler has shown superior LO-RF isolation and conversion loss View full abstract»

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  • A Ring-Oscillator-Based Wide Locking Range Frequency Divider

    Page(s): 470 - 472
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB) |  | HTML iconHTML  

    This letter proposes a wide locking range injection locked frequency divider (ILFD) and describes the operation principle of the ILFD. The circuit is made of a dual band two-stage differential complementary metal-oxide-semiconductor (CMOS) ring oscillator and is based on MOS switches directly coupled to the differential outputs of the ring oscillator. The divide-by-two ILFD can provide wide locking range and the measurement results show that at the supply voltage of 1.8-V, the divider free-running frequencies are 1.36GHz and 2.3GHz, and at the incident power of 0dBm, the locking range is about 1.75GHz from the incident frequency 1.9GHz to 3.65GHz at low band and 2.55GHz from 2.95GHz to 5.5GHz at high band View full abstract»

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  • V-Band GaAs pHEMT Cross-Coupled Sub-Harmonic Oscillator

    Page(s): 473 - 475
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    A V-band cross-coupled sub-harmonic injection-locked oscillator has been designed and fabricated using 0.15-mum GaAs pHMET technology. Based on the known harmonic injecting circuit topology, this oscillator was designed by a differential output approach, a low-Q microstrip-line resonator, and a current mirror, which has a free-running oscillation frequency around 60GHz with a tuning range of 2.5GHz (from 57.8GHz to 60.3GHz). The maximum single-end output power is 3.8dBm with a dc dissipation of 225mW under a -3V supply voltage. Within the input matching network for second (30GHz) and fourth (15GHz) sub-harmonic signals injection, it demonstrates the maximum locking ranges close to 120MHz and 30MHz, respectively View full abstract»

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  • Envelope Following-Based RF Transmitters Using Switching-Mode Power Amplifiers

    Page(s): 476 - 478
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (201 KB) |  | HTML iconHTML  

    This research presents a high-efficiency linear radio frequency transmitter applying the envelope-following technique to a switching-mode power amplifier. The use of predistorted envelope and quadrature-modulated signals can linearize the nonlinear behavior with fairly high average efficiency. The experimental results show that the proposed transmitter can deliver a 1.9-GHz CDMA2000 1times signal with high adjacent channel power ratio, low error vector magnitude, and high power added efficiency over a wide range of modulated output power View full abstract»

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    Page(s): 480
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    Page(s): 479
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  • IEEE Microwave and Wireless Components Letters Information for authors

    Page(s): c3
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  • Blank page [back cover]

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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