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Microwave Theory and Techniques, IEEE Transactions on

Issue 3 • Date Mar 1987

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Displaying Results 1 - 21 of 21
  • [Front cover - Mar. 1987 [T-MTT]]

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

    Page(s): 354 - 357
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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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  • Call for papers - focused section on electromagnetic devices for precision engineering

    Page(s): 358
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    Freely Available from IEEE
  • [Advertisement]

    Page(s): 359
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    Freely Available from IEEE
  • [Back cover - Mar. 1987 [T-MTT]]

    Page(s): b1 - b2
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    Freely Available from IEEE
  • A Penetrable Dielectric Waveguide with Periodically Varying Circular Cross Section

    Page(s): 282 - 287
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    For a penetrable dielectric waveguide with a periodically varying circular cross section, the modes that are exponentially decreasing in the cladding are considered. Their axial wavenumbers are determined by the null field approach and some plots are given showing their frequency dependence. From the numerical results, it is observed that two modes propagating in opposite directions interact destructively when the real parts of their axial wavenumbers differ by a multiple of the wavenumber of the corrugations. Both an upper and a lower cutoff frequency exists above (below) which only leaky modes exist. View full abstract»

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  • On the Numerical Solution of Fields in Cavities Using the Magnetic Hertz Vector

    Page(s): 288 - 295
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    The possibility of using a representation of the electromagnetic fields in terms of a two-component magnetic Hertz vector to calculate fields and frequencies in cavities is examined. The governing equation is the vector Helmholtz equation, and the model is tested by calculating fields in axially symmetric cavities. View full abstract»

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  • A Generalized Spectral-Domain Green's Function for Multilayer Dielectric Substrates with Application to Multilayer Transmission Lines

    Page(s): 326 - 335
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    A generalized full-wave Green's function completely defining the field inside a multilayer dielectric structure due to a current element arbitrarily placed between any two layers is derived in two-dimensional spectral-domain form. It is derived by solving a "standard" form containing the current element with two substrates on either side of it, and using an iterative algorithm to take care of additional layers. Another iterative algorithm is then used to find the field in any layer in terms of the field expressions in the two layers of the "standard" form. The locations of the poles of the Green's function are predicted, and an asymptotic form is derived along with the asymptotic limit, by use of which the multilayer Green's function can be used in numerical methods as efficiently as the single-layer grounded-dielectric-substrate Green's function. This Green's function is then applied to a few multilayer transmission lines for which data are not found in the literature to date. View full abstract»

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  • High-Speed Digital IC Performance Outlook

    Page(s): 245 - 259
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1816 KB)  

    This paper, which is a tutorial on high-speed GaAs digital IC's, was given as one of the 1984-1985 MTT-S Distinguished Microwave Lectures. It reviews GaAs FET technology and issues related to device/ circuit design and fabrication of digital circnits of MSI/LSI complexity operating at gigahertz clock frequencies; discusses limitations of the technology; compares GaAs technology with competing Si bipolar transistors, GaAIAs HEMT, and GaAIAs HBT technologies and projects performance of GaAs digital IC technology in applications where it will have a significant impact on microwave systems. View full abstract»

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  • Two-Tone Intermodulation in Diode Mixers

    Page(s): 307 - 314
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    This paper explores, experimentally and theoretically, the problem of minimizing second- and third-order intermodulation distortion in diode mixers. A numerical technique is presented which can be used to calulate internrodulation levels with unprecedented accuracy, and it is used to identify circuit and diode parameters which maximize dynamic range. It is shown that intermorhdation distortion is minimized by using low diode junction capacitance and series resistance, short-circuit embedding impedances, and high local-oscillator level. It is also shown that certain conditions which may optimize conversion loss, such as image enhancement, may severely exacerbate intermodulation. View full abstract»

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  • A Low-Frequency Investigation into the Discontinuity Capacitance of a Coaxial Line Terminated in a Lossless, Dielectric-Loaded Circular Waveguide (Short Paper)

    Page(s): 344 - 346
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    The problem of theoretically determining the normalized discontinuity capacitance of a dielectric-loaded coaxial termination has been reexamined and it is shown that, when frequency effects can be ignored, the solution to the problem may be expressed in the form of a rapidly convergent power series with power terms which depend only on the relative permittivity of the dielectrics and with coefficients which depend only on the line size. Values for the coefficients in the case of typical line sizes are presented and the accuracy of the power series solution is discussed. View full abstract»

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  • Coplanar Waveguides for MMIC Applications: Effect of Upper Shielding, Conductor Backing, Finite-Extent Ground Planes, and Line-to-Line Coupling

    Page(s): 260 - 267
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    Parasitic effects occurring in actual realizations of coplanar waveguides (CPW) for microwave integrated circuits on GaAs substrates, such as the influence of an upper shield, conductor backing, finite-extent ground planes, and line-to-line coupling, are discussed and evaluated. CAD-oriented analytical expressions are obtained for the electrical quasi-TEM parameters of the relevant waveguiding structures by means of exact or approximate conformal mapping techniques. Differences in electrical behavior with respect to ideal CPW's are highlighted, and practical design criteria are obtained for keeping cover height, ground-plane width, and line-to-line spacing effects to a minimum. View full abstract»

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  • General Solution for Excitation by Slotted Aperture Source in Conducting Cylinder with Concentric Layering

    Page(s): 321 - 325
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    We present a general matrix analysis for the electromagnetic fields produced by an aperture source on the inner metallic snrface of a concentrically layered structure. Each layer is homogeneous and characterized by arbitrary permittivity, conductivity and magnetic permeability. The structure itself is assumed to be of infinite length so Maxwell's equations yield separable solutions. An explicit result is given for the electric current density on the inner metallic cylindrical surface which could model the mandrel in a borehole logging tool. View full abstract»

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  • An Efficient Technique for Computing the Potential Green's Functions for a Thin, Periodically Excited Parallel-Plate Waveguide Bounded by Electric and Magnetic Walls

    Page(s): 276 - 281
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    An efficient formulation is described for calculating all vector and scalar potential Green's functions for a thin, infinitely long waveguide with periodic excitation. The Green's functions are represented by the first few terms of the modal expansion plus a quasi-static correction. This allows one to compute the Green's functions over a wide band of frequencies with little additional effort over that required for a single frequency. An attractive feature of the method is that the l/R free-space singularity exhibited by the potentials is explicitly extracted in the lowest order quasi-static term. Tfris is convenient for evaluating method-of-moments self-term contributions in closed form. The Green's functions have application for problems involving stripline structures such as Rotman lenses. View full abstract»

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  • A Low-Loss Ku-Band Monolithic Analog Phase Shifter

    Page(s): 315 - 320
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    A GaAs monolithic Ku-band analog phase shifter integrating 90° branch line coupler with planar varactor diodes has been fabricated for the first time. A phase shift of 109° +- 3° with an insertion loss of 1.8+-0.3 dB was measured from 16 to 18 GHz. A 360° phase shifter with 4.2+-0.9 dB insertion loss was realized in the same frequency range by connecting three phase-shifter chips in series. To our knowledge, this is the lowest insertion loss obtained by a 360° Ku-band phase shifter using monolithic circuits. In addition, hyperabrupt varactors using nonuniform doping profiles increased the phase shift by more than 30° and produced a more linear dependence of phase shift on control voltage. View full abstract»

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  • The Matrix Amplifier: A High-Gain Module for Multioctave Frequency Bands

    Page(s): 296 - 306
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    The characteristics of a new type of amplifier that makes simultaneous use of the additive and the multiplicative amplification process in one and the same module is discussed. The device, which achieves high-gain performance over multioctave bands, is a relative of the distributed amplifier. Initial experimental results demonstrated a small-signal gain of G = 13.8+-0.8 dB with -11.4 dB of maximum return loss between 2.0 and 21.5 GHz when using MESFET's manufactured on ion-implanted substrate material and G = 16.8+-0.9 dB gain over the 2.3-20.3-GHz frequency band in the case of vapor-phase-epitaxiaI material. The principle, the theory, and the experimental results are discussed in detail. View full abstract»

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  • A Spectral-Domain Analysis of Periodically Nonuniform Microstrip Lines

    Page(s): 336 - 343
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    Periodically nonuniform microstrip lines are analyzed on the basis of a numerical field calculation. Floquet's theorem is used to express all field quantities in terms of their spatial harmonics, so that the problem can be treated similarly to the uniform microstrip line. The boundary-value problem for the microstrip line in an enclosure is formulated in a rigorous way and then solved using Galerkin's method in the Fourier-transform domain. Numerical and experimental results are presented for a sinusoidal and a zigzag-shaped microstrip line. View full abstract»

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  • A Printed Circuit Stub Tuner for Microwave Integrated Circuits

    Page(s): 346 - 349
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    A novel microwave tuning eIement capable of continuous adjustment has been realized in the form of a planar printed circuit. As such, it is suitable for incorporation into microwave integrated circuits (MIC's), where it can be used for fine-tuning the impedance match between two parts of a circuit when the two parts are either subject to variations due to manufacturing tolerances or are difficult to model. In either case, the tuner is a compact on-circuit tuning facility which does not have to be removed after use. The tuner has been shown to have unique impedance-transforming properties, being capable of matching any realizable impedance to a 50-Omega load. Its main part consists of a coupled-line section and across the gap in the sectiou at different places along its length are positioned two short-circuit bridge conductors. Movement of these bridges produces the variation in impedance transfomration. View full abstract»

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  • Complex and Backward-Wave Modes in Inhomogeneously and Anisotropically Filled Waveguides

    Page(s): 268 - 275
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    A rigorous analysis of lossless inhomogeneously and anisotropically filled waveguides of arbitrarily shaped cross section is presented. The mode propagation constants squared appear as eigenvalues of a real infinite-dimensional characteristic matrix, which is, in the general case, nonsymmetric. Complex conjugate pairs of eigenvalues are then possible, which give rise to complex modes. Modes at cutoff are shown to be either TE or TM with real cutoff frequencies. An investigation of the power flow shows that backward-wave modes may exist as well. Different orthogonality relations are derived from which the power coupling between complex modes is investigated. View full abstract»

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  • A Fast and Reliable Method For Computer Analysis of Microwave Mixers (Comments)

    Page(s): 353
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    In Section IV of the above paper, Schiippert expressed conversion properties of the pumped diode junction in formulas (41)--(44). In general, that description does not satisfy well-known theory (e.g., [1], [2]). The subscript notation for the coefficients of the conversion admittance matrix used by Schüppert in formulas (42) and (44) is inauspicious, and it is probably a source of the mistaken form of the conversion matrix in formula (41). View full abstract»

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  • Phase Noise Reduction in FET Oscillators by Low-Frequency Loading and Feedback Circuitry Optimization

    Page(s): 349 - 352
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    Optimization of low-frequency Ioading allows reduction of 1/f converted noise in FET oscillators. Moreover, an appropriate low-frequency feedback between drain and gate gives an improvement over previous results. This improvement is explained by taking into account the properties of the noise autocorrelation function. 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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