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Microwave and Guided Wave Letters, IEEE

Issue 5 • Date May 1998

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Displaying Results 1 - 13 of 13
  • Mtt-S Transactions and Letters On-Line

    Page(s): 177 - 178
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    Freely Available from IEEE
  • Membrane-supported coplanar waveguides for MMIC and sensor application

    Page(s): 185 - 187
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    Membrane-supported coplanar waveguides (CPWs) are needed for low-dispersive and low-loss millimeter- and submillimeter waves as well as for power sensor applications. The authors demonstrate CPWs on polyimid membranes micromachined on gallium arsenide (GaAs) that meet the requirements of a typical microwave monolithic integrated circuit (MMIC) process. The influence of the design parameters is simulated by finite difference in frequency domain (FDFD), in excellent agreement with the experiment. For a membrane CPW with ground to ground spacing of only 50 μm and characteristic impedance of 115 /spl Omega/, relative effective dielectric constants near 1.02 and attenuation of 0.14 dB/mm at 25 GHz have been achieved. View full abstract»

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  • Comments on "A super absorbing boundary condition for the analysis of waveguide discontinuities with the finite-difference method" [and reply]

    Page(s): 208 - 209
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    For the original paper see ibid., vol. 7, p. 147-149 (June 1997). In the aforementioned work, it is pointed out that the authors may have overlooked the paper by Ramahi et al. (see IEEE Trans. Antennas and Propag., vol. 39, p. 350-353, Mar. 1991), which introduced a numerically derived Absorbing Boundary Condition (ABC) for the solution of open region scattering problems. In this paper, the idea was to present the unknown field or its derivative at a terminal node in terms of a weighted summation of neighboring nodes that lie in the interior. The weighting coefficients are solved for by representing the field at the terminal node in terms of a finite number of its spatial harmonics (three or five dominant harmonics). The concept was demonstrated by applying it to cylindrical harmonics in the context of the finite-element method, whereas the authors of the above paper considered planar waveguide harmonics in the context of the finite-difference method. The authors reply to this comment. View full abstract»

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  • A low phase-error 44-GHz HEMT attenuator

    Page(s): 194 - 195
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    Radio frequency (RF) subsystems for emerging millimeter-wave applications require monolithic microwave integrated circuit (MMIC) attenuators with constant phase over the attenuation range. In this work, we present the results for a 44 GHz stepped attenuator implemented in high electron mobility transistor (HEMT) MMIC technology. Use of a switched-path topology provides a high attenuation range (>30 dB) with good phase flatness (<7° p-p) and return loss (>14.5 dB) over the attenuation range. The same design topology should be well suited for other frequencies throughout the upper microwave and lower millimeter-wave range View full abstract»

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  • A dual CP slot antenna using a modified Wilkinson power divider configuration

    Page(s): 205 - 207
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    A dual circularly polarized (CP) slot antenna based on a proposed equal-split Wilkinson power divider is presented. An offset-fed slot antenna, which was analyzed using the method of moments together with a mixed potential integral equation, was used to replace the lumped resistor in the divider. A dual CP slot antenna operating at S-band was designed and demonstrated experimentally. The antenna possessed a return loss bandwidth of 39.3%, an isolation bandwidth of 10% for VSWR <2, and 3-dB axial ratio bandwidth of 28% View full abstract»

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  • A hybrid nonlinear delay line-based broad-band phased antenna array system

    Page(s): 182 - 184
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    Nonlinear delay line (NDL) technology has been utilized to implement a proof-of-principle, broadband, 8-channel, linear, hybrid NDL-based phased antenna array (PAA) system. The hybrid NDLs provide up to 267 ps analog, variable true time delay (TTD) with <5-dB measured insertion loss. A PAA system incorporating wide-band feed, transition, and antenna elements has been developed for broad-band (4-18 GHz), electronically controlled beam steering. The current system has demonstrated up to ±180 beam steering from 4 to 5 GHz, and ±6° at 6 GHz in good agreement with theoretical predictions; monolithic implementations have been designed to provide ±19° beam steering at frequencies up to 18 GHz and are currently being fabricated. This system provides a wide-band, low-cost, high-precision alternative to conventional PAA technologies View full abstract»

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  • LSE-mode balun for hybrid integration of NRD-guide and microstrip line

    Page(s): 199 - 201
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    A recently proposed hybrid integration technology of NRD-guide and planar circuits provides an alternative for exploiting advantageous features of the two complementary structures in view of three-dimensional circuit design at millimeter-wave frequencies. Such an integration scheme has been developed for use of the second fundamental mode (LSM) having the lowest transmission loss. In this work, a new balun structure (transition) integrating NRD-guide and microstrip line is reported for the first fundamental mode (LSE). A TLM algorithm is used to model and optimize the proposed LSE-mode related NRD-guide/microstrip line transition. Electrical characteristics of the new balun are studied theoretically and experimentally. Calculated and measured results are found to be in good agreement for designed experimental prototypes at 18-22 GHz View full abstract»

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  • An effective PML for the absorption of evanescent waves in waveguides

    Page(s): 188 - 190
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    As emphasized by several authors in literature, the evanescent modes are not absorbed by usual perfectly matched layers (PMLs) terminating waveguiding structures. The purpose of this work is to present a new version of the PML that allows a substantial absorption of such waves to be achieved View full abstract»

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  • Frequency detector with power combiner dividers

    Page(s): 179 - 181
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    The author describes a microwave frequency detector made in microstrip technique. The system consists of two power dividers and three transmission lines. Ratio of amplitudes of output signals determines frequency of input signal. Despite simple structure, the frequency detector has very attractive parameters. Practically made the detectors worked in S in Ku frequency band View full abstract»

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  • A new beam-scanning technique by controlling the coupling angle in a coupled oscillator array

    Page(s): 191 - 193
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    The authors present a new technique for electronic beam scanning of a coupled oscillator array. A constant phase progression in a coupled oscillator array is achieved by controlling the coupling phase of the outermost coupling circuits only, while that of the innermost coupling circuits is zero and all free-running frequencies of the oscillators are the same. Analytical solution of nonlinear phase dynamic equations changes periodically as a piecewise-linear function of coupling phase only. The theory developed here is verified using a four-element oscillator array operating at 6.16 GHz. The full scan range is measured to be -17° to 18° off broadside. This scan range is very close to the theoretically achievable scan range of -19.2° to 19.2° for this array View full abstract»

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  • Design of a beam-switching active microstrip antenna array

    Page(s): 202 - 204
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    An active microstrip antenna array with dual switching beams were developed and demonstrated. The array contained several active antennas and an extra amplifier-embedded coupling (microstrip) line. Two injection-locking signals were used in the design, that is, the free-space mutual coupling between antennas and the injection signal on the coupling line tapped from the first oscillator in the array. By turning on and off the amplifier on the line, these two signals dominated in turn, producing two radiation modes with different main beams. A three-element H-plane array and a two-element E-plane array were designed and measured. Both of the arrays had an out-of-phase radiation mode when the amplifier was turned off, and had an in-phase mode when the amplifier was on. Also, clean frequency spectra and good radiation patterns were measured, which demonstrated the validity of the present design View full abstract»

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  • Efficient transient compression using an all-silicon nonlinear transmission line

    Page(s): 196 - 198
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    Nonlinear transmission lines (NLTLs) have so far only been fabricated on GaAs. Here, an NLTL was monolithically integrated on a 2000-Ω·cm silicon substrate, demonstrating the applicability of the NLTL concept to silicon millimeter-wave integrated circuits (SIMMWICs). The fall time of 74 ps of a 4-GHz sinewave was compressed to 32 ps at the output of the NLTL, in accordance with theory. This is the first working NLTL on silicon to our knowledge View full abstract»

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Aims & Scope

This Periodical ceased production in 2000. The current retitled publication is IEEE Microwaves and Wireless Component Letters.

Full Aims & Scope