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Microwave Theory and Techniques, IEEE Transactions on

Issue 3 • Date Mar. 1982

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Displaying Results 1 - 15 of 15
  • [Front cover - Mar. 1982 Transactions]

    Page(s): f1 - f2
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    Freely Available from IEEE
  • Analysis of the Symmetrical Modes for an Eccentrically Cladded Fiber

    Page(s): 217 - 220
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    This paper examines the core and the cladding modes of an eccentrically cladded three-layer dielectric waveguide. The solutions are specialized to small eccentricities, and exact closed-form expressions for the normalized deviations of the cutoff wavenumbers from those of the concentric case are determined. Numerical results for the symmetrical cladding modes of the fiber are given. View full abstract»

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  • Ridged Waveguides for Ultra-Broad-Band Light Modulators

    Page(s): 220 - 226
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    The electromagnetic field of the dominant mode propagating in the inhomogeneously dielectrically loaded double ridged waveguide is given in terms of a modal series expansion. The numerical evaluation of the propagation constant reveals a remarkably linear dispersion diagram in close agreement with measurements performed in the 8-40-GHz range. Based on this analysis, the bandwidth of a ridged waveguide CO 2 -laser modulator is calculated to exceed 40 GHz, when a 25-mm long CdTe crystal is used as electrooptic material. View full abstract»

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  • Integrated Balanced BPSK and QPSK Modulators for the Ka-Band

    Page(s): 227 - 234
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    Microwave integrated circuit (MIC) balanced biphase-shift-keying (BPSK) and quadri-phase-shift-keying (QPSK) modulators have been achieved in the 27-GHz band. The modulators are fabricated using a combination of microstrip lines and slot lines, viz., tow-sided MIC. The diodes used are beam-lean Schottky-barrier diodes. Balanced BPSK modulation is performed by path-switching and mode transformation from the slot line to microstrip lines. The insertion loss is 2.2 dB at a carrier frequency of 27 GHz. The phase error and the amplitude deviation are less than 1° and 0.5 dB, respectively. The QPSK modulator consists of two BPSK modulators, a power divider, and a branch-line hybrid coupler. The configuration of the modulator is the parallel-connected type. The insertion loss is 6.3 dB at a carrier frequency of 27 GHz. The phase error is less than 2°, and the rise time and fall time of the modulated earner are less than 300 ps. The isolation between the carrier input port and the QPSK modulated earner output port is greater than 25 dB. These modulators can be extended to the millimeter-wave band. View full abstract»

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  • A 26-GHz Miniaturized Mic Transmitter/Receiver

    Page(s): 235 - 242
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    A very compact 26-GHz transmitter/receiver for high-speed digital radio subscriber systems has been developed. The transmitter/receiver makes extensive use of MIC technology in the RF sections. Transmitting power of 18 dBm and a receiving noise figure of less than 12 dB is obtained. The freqnency of the local oscillator is stabilized to within +-100 ppm by means of a high-Q dielectric resonator. The bit error rate is measured in order to evaluate the overall system, and good performance of the equipment is obtained. A field test rising this equipment is now under way. The technique described in the text can be extended to transmitter/receiver for terrestrial radio relay systems and satellite communication systems. In addition, the various MIC components developed here can be scaled to the millimeter-wave region. View full abstract»

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  • Microwave Wide-Band Model of GaAs Dual Gate MESFET's

    Page(s): 243 - 251
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    A multioctave model of GaAs dual gate MESFET's is presented. It consists of 28 frequency independent elements and is valid between 2 and 11 GHz. Dual gate FET's with and without intergate ohmic contact have been considered. The modeling method utilized consists in separate dc and HF characterization and equivalent circuit determination of the active device parts in their actual bias conditions. Thereby, two goals are obtained : a) The topology of the overall model can be derived from well-known simpler, partial ones; and b) the starting values of optimization are precise enough to allow reliable physical solutions. View full abstract»

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  • Numerical Analysis of Nonlinear Solid-State Device Excitation in Microwave Circuits

    Page(s): 251 - 259
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    This paper presents an efficient technique for the numerical determination of voltage and current waveforms when a microwave circuit containing one or more nonlinear elements is excited by a single frequency source. The approach described here is readily applied to microwave networks represented by a large number of equivalent circuit elements, either lumped or distributed. A significant feature of this paper is the detailed investigation of the problem of convergence, using this new technique. The generality of the techniqne is illustrated through its application to studies of the excitation of varactor, Schottky-barrier, and IMPATT diodes in waveguide circuits. In addition, the relationship of this method to the multiple reflection approach is discussed and the convergence mechanism of this reflection technique is studied. View full abstract»

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  • Harmonic Power Combining Of Microwave Solid-State Active Devices

    Page(s): 260 - 268
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    A method for combining the power in a selected harmonic of the fundamental frequency for a symmetrical array of oscillating solid-state devices is described and demonstrated. These combiners convert fundamental power to harmonic power with filtering accomplished by symmetry. This technique appears useful for improving the performance of microwave and millimeter-wave power sources by effectively enhancing the frequency-power limitations of existing solid-state devices. An example of the method is provided by a simple three-phase frequency-tripling varactor-tuned transistor oscillator. View full abstract»

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  • Symmetrical Combiner Analysis Using S-Parameters

    Page(s): 268 - 277
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    A general theory is developed to predict the potential efficiency (eta) and input impedance ( Z ic) of symmetrical N-way combining networks in terms of scattering parameters. A simplified version of the theory, assuming perfect symmetry, is then implemented on a semiautomatic network analyzer (SANA) which is used to characterize 2-way and 16-way TM 010 combining networks. These simplified theoretical assumptions have also been used to predict the degradation effects of power combiners when one or more sources fail. Results indicate that there is room for improvement if proper design techniques are applied. View full abstract»

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  • TE /sub 11/ to HE /sub11/ Cylindrical Waveguide Mode Converters Using Ring-Loaded Slots

    Page(s): 278 - 285
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    A theoretical parameter study is given of a TE 11 to HE 11 mode converter consisting of a section of cylindrical corrugated waveguide with ring-loaded slots. The analysis, using modal field-matching techniques to determine the scatter matrix of the converter, allows the return loss to be computed accurately. For a wide range of waveguide sizes it is shown that a bandwidth ratio of 1.5 with a return loss better than 30 dB is possible. The low-frequency performance of the converter is limited by the deterioration in return loss, while at high frequencies the generation of a small amount of unwanted EH 12 mode is the restriction. If the effects of this mode can be neglected, operation over a wider bandwidth is possible, particularly for larger waveguide size. View full abstract»

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  • Measurement of the Dielectric Constant and Loss Tangent of Thallium Mixed Halide Crystals KRS-5 and KRS-6 at 95 GHz

    Page(s): 286 - 292
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    The dielectric constants and loss tangents of KRS-5 and KRS-6 thallium halide mixed crystals have been measured at 95 GHz using both the shorted waveguide (SWG) reflection method and the Fabry-Perot (F-P) transmission method on samples filling standard WR-10 waveguide. The results--KRS-5: epsilon' r = 31; tan delta = 1.8 x 10 -2; KRS-6: epsilon' r = 29, tan delta = 2 x 10/sup-2/-- agree reasonably well with a simple theoretical fit to the far-infrared Iattice absorption of TIBr and TICI centered at about 1400 GHz. The dielectric samples were hot-pressed into copper wafers with dimensions matching WR-10 waveguide, and then machined and polished to obtain flat, parallel air-dielectric interfaces. View full abstract»

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  • A More Accurate Model of the TE/sub10/ Type Waveguide Mode in Suspended Substrate

    Page(s): 293 - 294
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    An analytical model of the suspended substrate transmission Iine which includes the grooves used to support the substrate is presented. The model predicts a lower cutoff frequency of the TE 10 type waveguide mode than that without the grooves. The analysis is confirmed by experiments. View full abstract»

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  • Correction to "Asymptotic High-Frequency Modes of Homogeneous Waveguide Structures With Impedance Boundaries"

    Page(s): 296
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    The treatment of Section V in the above paper was incomplete and, as such, a bit misleading. In fact, the existence question for solutions of equation (53) for f/sub 2/ = (pi/sub 2/, m/sub 2/) did not properly take into account the degeneracy of the basic modes f/sub 1/ = (pi/sub 1/, m/sub 1/). It is known that for a solution to exist, the right-hand side of a deterministic equation like (53) must be orthogonal to all solutions of the homogeneous adjoint problem, which in this case is the basic problem with solutions f/sub 1/. Without degeneracy, equation (56) would be that condition. However, since there are at least two linearly independent solutions f/sub 1i/, there are at least two such conditions, which leads to a contradiction except if f/sub 1/ in (53) is chosen in a special way. Let us denote the admissible f/sub 1/ in (53) by f'/sub 1/ and it can be written as a linear combination of any complete set of degenerate basic modes corresponding to the same parameter beta/sub 1/:f'/sub 1/ = Sigma alpha/sub i/f/sub 1i/. View full abstract»

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  • Patent abstracts

    Page(s): 297 - 300
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    These patent abstracts of recently issued patents of interest to microwave engineers are intended to provide the minimum information necessary for readers to detennine if they are interested in examining the patent in more detail. Complete copies of patents are available for a small fee by writing: U.S. Patent and Trademark Office, Box 9, Washington, DC, USA. View full abstract»

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  • [Back cover - Mar. 1982 Transactions]

    Page(s): b1 - b2
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    Freely Available from IEEE

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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