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Microwave Theory and Techniques, IEEE Transactions on

Issue 4 • Date Apr 1986

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Displaying Results 1 - 23 of 23
  • [Front cover - Apr. 1986 [T-MTT]]

    Page(s): f1 - f2
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    Freely Available from IEEE
  • Editorial

    Page(s): 377 - 378
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    Freely Available from IEEE
  • Comparison of Quasi-Static and Exact Electromagnetic Fields from a Horizontal Electric Dipole Above a Lossy Dielectric Backed by an Imperfect Ground Plane

    Page(s): 379 - 387
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    In most microstrip transmission lines, analysis is made assuming that a quasi-TEM mode exists and propagates down the line. The primary objective of this paper is to obtain the region of validity of this assumption. The second objective of this paper is to derive the expressions for the fields for a horizontal electric dipole over a Iossy dielectric medium backed by an imperfect ground plane. It is shown that, to a first approximation, fields at the air-dielectric interface are independent of the ground plane conductivity. Since we are interested in coupfing between lines, our interest is in the computation of the fields primarily at the air-dielectric interface. Finally, numerical results are presented to show where the quasi-static approximations deviate from the exact solution for a given microstrip geometry as the frequency of operation or the observation point is changed. View full abstract»

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  • The Declining Drain Line Lengths Circuit - A Computer Derived Design Concept Applied to a 2 26.5-GHz Distributed Amplifier

    Page(s): 427 - 435
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    The principle of the "declining drain line lengths" has emerged as a successful concept in the pursuit of improved gain flatness and bandwidth. The optimized performance parameters of an "identical links" gain module are compared to those of a "declining drain line lengths" gain module, and the advantages of one design principle over the other are discussed. In addition, the paper studies the RF voltages and currents of the circuits' GaAs MESFETs and draws some qualitative conclusions as to the causes of gain limiting when approaching nonlinear operation. Finally, experimental results of a power module based on the "declining drain line lengths" principle are reported. The hybrid amplifier which incorporates five active devices with 0.25-µm gates achieves a small signal gain of G = 6.1+-0.6 dB from 2-27 GHz. Measurements of its output power, reflection coefficients and noise figure are afso discussed. View full abstract»

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  • Patent Abstracts (Apr. 1986 [T-MTT])

    Page(s): 476 - 479
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    Freely Available from IEEE
  • [Advertisement]

    Page(s): 480
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    Freely Available from IEEE
  • [Back cover - Apr. 1986 [T-MTT]]

    Page(s): b1 - b2
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    Freely Available from IEEE
  • A Completely Theoretical Design Method of Dielectric Image Guide Gratings in the Bragg Reflection Region

    Page(s): 420 - 426
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    This paper presents a new and completely theoretical accurate method for the design of dlelectic image guide gratings. Our method is based on a network approach that can easily analyze, with satisfactory approximations, the interaction of dielectric step discontinuities. These are the fundamental constituents of our gratings. Measurements on a filter modeled at X-band show excellent agreement with the design characteristics. View full abstract»

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  • New Concepts in Traveling-Wave Amplifiers (Short Paper)

    Page(s): 446 - 451
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    Two new networks with the potential for good port VSWR over very broad bandwidths are proposed for use in both low-power balanced amplifiers, and high-power combining systems. These new structures which are called Low-Sidelobe and Squintless Traveling-Wave Amplifiers (LSTWA and SQTWA, respectively) have been derived from conventional Traveling-Wave Amplifiers (TWA) by utilizing Phased Array Antenna concepts and design techniques. Using Monte-Carlo simulations the relative performance of the three structures is compared. Finite loss and mismatch effects are also considered. View full abstract»

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  • On the Noise Parameters of Isolator and Receiver with Isolator at the Input (Short Paper)

    Page(s): 451 - 453
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    Noise parameters of an isolator and those of a receiver with an isolator at the input are reviewed. Some comments on recently published results are offered. View full abstract»

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  • Theoretical Considerations on the Use of Circularly Symmetric TE Modes for Digital Ferrite Phase Shifters (Correction)

    Page(s): 475
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    Recently, we have become aware of increased publication activity by authors who refer to the above early paper. We felt that it is particularly timely, therefore, to inform those concerned that in the above paper a few formulas, unfortunately, are in error. View full abstract»

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  • General Analysis of a Parallel-Plate Waveguide Inhomogeneously Filled with Gyromagnetic Media

    Page(s): 388 - 395
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    The boundary value problem for a parallel-plate waveguide filled with inhomogeneous gyromagnetic medium is expressed and thoroughly examined in terms of a linear operator equation. A suitable vector definition of transverse mode functions is given and their completeness and orthogonality are proved. Applying a new set of continuity conditions for field components normal to the cross-sectional interface, the transfer matrix for the multilayered parallel-plate waveguiding structure is determined and used to formulate a characteristic equation. The analysis is illustrated by the numerical investigation of eigenfunctions and eigenvalues of a two layer ferrite-air guide. View full abstract»

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  • On the Measurement of Noise Parameters of Microwave Two-Ports (Short Paper)

    Page(s): 456 - 458
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    A novel procedure for determining the noise parameters of microwave two-ports is introduced. In this procedure, the computations necessary to find the noise parameters from the set of measurements of noise temperature (noise figure) are greatly simplified. The assessment of accuracy with which the noise parameters can he determined from a given set of measurement data is straightforward. View full abstract»

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  • Analysis of a Longitudinal Gyroelectric Discontinuity Inside a Fiber Waveguide

    Page(s): 396 - 404
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    The scattering of guided electromagnetic waves from a finite-length longitudinal gyroelectic discontinuity inside a fiber waveguide is treated analytically. An integral equation approach is employed to formulate the corresponding boundary-value problem. The induced field inside the gyroelectic discontinuity region is expanded into a Fourier-type series in terms of the well-known cylindrical waves M and N plus a purely longitudinal wave Q. Then the method of moments is applied to decouple the basic integral equation. The resulting infinite coupled system of equations is truncated and solved numerically. After determining the field inside the discontinuity, the scattered far field inside the dielectric-rod waveguide is computed by employing a steepest descent integration technique. Numerical results for the scattering coefficients of an incident HE11 dominant mode are obtained. Finally, design principles are discussed for practical components based on the treated longitudinal gyroelectric discontinuity. View full abstract»

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  • Ka-Band Front End with Monolithic, Hybrid, and Lumped-Element IC's

    Page(s): 412 - 419
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    A Ku-band front end has been developed which integrates a low-loss wide-band monolithic mixer, a two-stage hybrid IF amplifier, and a lumped-element Gunn local oscillator (LO). Small size (0.5 cubic in), high performance, and potentially low production cost have been demonstrated through the application of highly compatible IC construction techniques. View full abstract»

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  • Improved X-Band FM Discriminator (Short Paper)

    Page(s): 442 - 446
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    The technique of coherent carrier-addition, using injection synchronization of a narrow-band Gunn oscillator, for improving the performance of an X-band frequency discriminator has been examined in detail. The discriminator is implemented from a single magic tee, two adjustable AM detectors, two sliding shorts, a circulator, an isolator, and a difference amplifier of gain unity. Experimental results are presented in partial support of the conclusions of the analysis. Normal operation of the discriminator in absence of the coherent carrier is also described as a special case of the above analysis. View full abstract»

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  • Characteristic Impedance of Transmission Lines with Arbitrary Dielectrics Under the TEM Approximation (Short Paper)

    Page(s): 472 - 475
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    This paper gives a procedure for computing the characteristic impedances of TEM or quasi-TEM transmission lines with arbitrary cross sections and arbitrary dielectrics. Special consideration is given to conductors of finite cross-sectional extent. The solution is obtained by the method of moments using pulse functions for the expansion of charge density and point matching for testing. Numerical examples are given and compared with solutions obtained by other methods. View full abstract»

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  • Two Core Radii for Minimum Total Dispersion In Single-Mode Step-Index Optical Fibers (Short Paper)

    Page(s): 453 - 456
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    Starting from the operating wavelength and the chemical composition of the materials that integrate the core and cladding of an optical fiber, a method was developed for the calculation of the values of the core radii; it allows fiber operation in a monomode region with minimum total dispersion. The study is restricted to step-index fibers and the selected theoretical model is based on the weakly-guiding characteristic equation. From these considerations it is possible to obtain two different values of core radii for a given source operating wavelength. The theory described allows the characterization of an optical fiber for use with a given light source and extends a previously described theory. View full abstract»

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  • Novel Design Approach for X-Band GaAs Monolithic Analog 1/4 Frequency Divider

    Page(s): 436 - 441
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    A novel analog frequency divider which can generate a 1/4 frequency component is proposed. The frequency divider consists of a dual-gate FET and a two-stage capacitor-resistor coupled amplifier. This circuit configuration also enables achieving a small-size GaAs MMIC analog frequency divider. In this analog frequency divider, the input signal f0 is mixed with signal component f0/x caused by noise or transients in a feedback loop. Then, a (1 -- 1/x)f0 IF component is induced and is again mixed with the input signal. This process delivers the f0/x component regeneratively. Resultant continuous signal components f0/x and (1-1/x)f0 have a harmonic relation when the system reaches a steady state. The f0/x component can be mainly obtained at an output port of the frequency divider. The operation band was simulated using a SPICE II computer program. The designed bandwidth and conversion gain for the 1/4 frequency divider are 8.5-10.6 GHz and -3 dB, respectively. Based on the simulation, a GaAs monolithic analog 1/4 frequency divider was made and tested. The developed 1/4 frequency divider provides a 8.5-10.2-GHz operation bandwidth and --5+-1-dB conversion gain. The designed and experimental values are in good agreement. The frequency division band can be shifted to higher frequency (10.65-11.2 GHz) by adopting the external matching circuit at the GaAs chip output port. The proposed analog frequency divider circuit can be applied not only for 1/4 frequency division, but also for 1/n frequency division (interger n > 2). View full abstract»

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  • Analysis of Square-Spiral Inductors for Use in MMIC's (Short Paper)

    Page(s): 467 - 472
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    A method analysis of square spiral inductors for use in monolithic microwave integrated circuits (MMIC's) is presented. The method is based on the coupled microstrip-line theory and incorporates a novel solution to the multicoupled-line problem. The analysis includes the effect of the discontinuities at the right-angled bends in the lines, and also the feedback effect where the lead-out bridge crosses the lines. The method can be used to analyze components with an arbitrary number of spiral turns. Theoretical results are compared with the measured S-parameters of a 3 1/2-turn component over the range 2-12 GHz, and reasonable agreement between the two is found. View full abstract»

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  • Bragg Reflection Characteristics of Millimeter Waves in a Periodically Plasma-Induced Semiconductor Waveguide

    Page(s): 406 - 411
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    Theoretical analysis on the Bragg reflection characteristics of millimeter waves in a periodically plasma-induced semiconductor waveguide is presented. The plasma is assumed to be generated by light illumination. Numerical examples are given which show the dependence of the Bragg reflection characteristics on the length of the plasma-induced section and on the plasma density. Since the period can be changed by altering the illumination pattern, this type of periodic structure may be developed to tunable filters or tunable DBR oscillators for millimeter-wave region. View full abstract»

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  • Measurement Techniques for Planar High-Frequency Circuits (Short Paper)

    Page(s): 463 - 467
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    Planar bismuth bolometers can be used as measuring elements in planar millimeter-wave circuits. These devices are easy to fabricate and calibrate; moreover, their responsivity is thought to be nearly independent of frequency throughout the millimeter-wave regime. Furthermore, they are inherently linear detectors over as much as seven orders of magnitude. Noise-equivalent powers of 2x 10/sup-10/ W/Hz12/ can be attained. The high sensitivity of these devices makes them suitable for use in probes. Techniques for measurement of current and reflection coefficient are proposed. Trial measurements, using simulation at 1 GHz, are described. View full abstract»

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  • The Near Field of an Insulated Dipole in a Dissipative Dielectric Medium (Short Paper)

    Page(s): 459 - 463
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    The near field of uninsulated dipole antenna in a dissipative dielectric medium is important in microwave hyperthermia and geophysical applications. In this paper, the electric field near an insulated dipole has been calculated by the direct numerical evaluation of a surface integral over the insulation. The computed results are compared with those previously obtained by an approximate numerical calculation. View full abstract»

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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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