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Microwave Theory and Techniques, IEEE Transactions on

Issue 8 • Date Aug. 1975

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Displaying Results 1 - 23 of 23
  • [Front cover - Aug. 1975]

    Page(s): f1 - f2
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    Freely Available from IEEE
  • Comments on "Transmission Line Impedance Matching Using the Smith Chart" [Letters]

    Page(s): 715
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    For the recently discussed problem of R. M. Arnold of finding the characteristic impedance and electrical length of a uniform, loss-free transmission line which transforms a given impedance into another given impedance, an alternate approach using an elementary auxiliary calculation (with no trial and error) has been given in. View full abstract»

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  • Freely Available from IEEE
  • [Back cover]

    Page(s): b1 - b2
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    Freely Available from IEEE
  • Explicit Design Formulas for Waveguide Single-Sided Filters

    Page(s): 681 - 689
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    Explicit formulas are given for the design of optimum single-sided waveguide filters. Using a uniform waveguide with iris-coupled series stubs irregularly spaced along the waveguide, this class of filter results in a significant reduction in the number of resonators required to meet single-passband and single-stopband specifications over conventional techniques. Design information is given for both the Chebyshev and elliptic function cases from which the required structure may be obtained without recourse to synthesis procedures. Computer simulations of the response characteristics of both the quarter- and modified three-quarter-wave coupled quasi low-pass and the quasi high-pass designs are given. Experimental results on fifth-degree Chebyshev filters operating in X band for the former case are presented showing close agreement with theory. View full abstract»

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  • Harmonic Mixing with an Antiparallel Diode Pair

    Page(s): 667 - 673
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    An analytical and experimental investigation of the properties of an antiparallel diode pair is presented. Such a configuration has the following unique and advantageous characteristics as a harmonic mixer: 1) reduced conversion loss by suppressing fundamental mixing products; 2) lower noise figure through suppression of local oscillator noise sidebands; 3) suppression of direct video detection; 4) inherent self protection against large peak inverse voltage burnout. These results are obtained without the use of either filters or balanced circuits employing hybrid junctions. View full abstract»

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  • The Equivalent Circuit of Some Microstrip Discontinuities

    Page(s): 655 - 660
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    The experimental characterization of some microstrip structures of common interest, including symmetrical T junctions, is described. Some results are compared with data derived from recent three-dimensiotial static theory and from the uniform plane-wave model. It is concluded that while the three-dimensional theory requires further improvement, it is generally in much better agreement with the measured data than the two-dimensional uniform plane-wave model. View full abstract»

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  • Bias Frequency Modulation of GaAs Millimeter-Wave Diode Oscillators (Short Papers)

    Page(s): 700 - 703
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    A method for estimation of FM bias modulation sensitivity of a Gunn-diode oscillator is presented under the assumption of incomplete domain formation for a very short diode. Experimental measurements at 33 and 11.3 GHz are shown as compared with this estimate and the decrease of sensitivity with external Q, for modulation frequency high enough to eliminate thermal effects, is demonstrated. View full abstract»

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  • An Accurate Determination of the Characteristic Impedance of the Coaxial System Consisting of a Square Concentric with a Circle (Letters)

    Page(s): 714 - 715
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    Bowman has shown how the rectangular region in the w plane of Fig. 1, bounded by 0ABC, may be mapped conformally into the trapezoidal region in the z plane of Fig. 1, bounded by 0ABC, by means of the successive transformations: View full abstract»

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  • Worst Case Network Tolerance Optimization

    Page(s): 630 - 641
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    The theory and its implementation in a new user oriented computer program package is described for solving continuous or discrete worst case tolerance assignment problems simultaneously with the selection of the most favorable nominal design. Basically, the tolerance problem is to ensure that a design subject to specified tolerances will meet performance or other specifications. Our approach, which is believed to be new to the microwave design area, can solve a variety of tolerance and related problems. Dakin's tree search, a new quasi-Newton minimization method, and least pth approximation are used. The program itself is organized such that future additions and deletions of performance specifications and constraints, and replacement of cost functions and optimization methods are readily realized. Options and default values are used to enhance flexibility. The full Fortran listing of the program and documentation will be made available. View full abstract»

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  • Inductance of Nonstraight Conductors Close to Ground Return Plane (Short Papers)

    Page(s): 706 - 708
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    Measurement and calculation of the inductance of a nonstraight conductor close to ground return plane are considered. An equivalent circuit model solution is given, and the results are compared to measurements for a corner-type geometry. Much larger changes in inductance as a function of frequency have been observed for the corner-type geometry than for the equivalent straight-conductor geometry. The circuit model can be used to predict the inductance for other configurations. View full abstract»

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  • Effect of Temperature on Device Admittance of GaAs and Si IMPATT Diodes

    Page(s): 673 - 680
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    The effect of temperature on the small-signal admittance of IMPATT diodes with uniformly doped and high-low doped (Read) structures is investigated experimentafly and theoretically. Small-signal admittance characteristics of X-band Si p+-n-n+, GaAs M-n-n+ (Schottky-uniform), and GaAs M-n+-n-n+ (Schottky-Read) IMPATT diodes are measured at various junction temperatures for different dc current levels. Small-signal analysis is performed on GaAs IMPATT diodes of uniformly doped and high-low doped structures, and the calculated results on temperature dependence of the device admittance are compared with the experimental results. Reasonable agreement is found between theory and experiment. It is shown that GaAs IMPATT diodes are superior to Si diodes in admittance temperature characteristics and that the uniformly doped structure has a small admittance temperature coefficient in magnitude, compared to the high-low doped structure. It is also shown by calculation that the admittance temperature coefficient of a punch-through diode is small in magnitude, compared to that of a non-punch-through diode. View full abstract»

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  • Calculation of Microstrip Discontinuity Inductances

    Page(s): 648 - 655
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    Inductive components of microstrip discontinuity equivalent circuits are calculated by the Galerkin method. The formulation and method of calculation are discussed and a large number of numerical results for symmetric corners, T junctions, and steps changes are presented. These results compare well with experiment. View full abstract»

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  • Approximations for the Symmetrical Parallel-Strip Transmission Line (Letters)

    Page(s): 712 - 714
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    A single approxation that is valid for the capacitance of both "wide" and "narrow" parallel-strip transmission lines was derived by assuming that the current distribution is uniform. An approximate formula for the repulsive force between the strips was also derived. View full abstract»

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  • Numerical Solution of Steady-State Electromagnetic Scattering Problems Using the Time-Dependent Maxwell's Equations

    Page(s): 623 - 630
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    A numerical method is described for the solution of the electromagnetic fields within an arbitrary dielectric scatterer of the order of one wavelength in diameter. The method treats the irradiation of the scatterer as an initial value problem. At t = 0, a plane-wave source of frequency f is assumed to be turned on. The diffraction of waves from this source is modeled by repeatedly solving a finite-difference analog of the time-dependent Maxwell's equations. Time stepping is continued until sinusoidual steady-state field values are observed at all points within the scatterer. The envelope of the standing wave is taken as the steady-state scattered field. As an example of this method, the computed results for a dielectric cylinder scatterer are presented. An error of less than ±10 percent in locating and evaluating the standing-wave peaks within the cylinder is achieved for a program execution time of 1 min. The extension of this method to the solution of the fields within three-dimensional dielectric scatterers is outlined. View full abstract»

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  • Variation of the Electrical Characteristics of an Inhomogeneous Microstrip Line with the Dielectric Constant of the Substrate and with the Geometrical Dimensions (Short Papers)

    Page(s): 703 - 706
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    Studying systematically the variations of electrical characteristics of microstrip lines with the width w of the line, the thickness h, and the dielectric constant epsilonr of the substrate, we have obtained a perfect linear variation with epsilonr. Then using a least squares method, we have been able to give an analytical expression of capacitances usable for 1 ≤ epsilonr ≤ 100 and 0.04 ≤ w/h ≤ 10. The importance of this result is that we can give impedances and phase velocities without any computation. View full abstract»

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  • A New Fast and Accurate Algorithm for the Computation of Microstrip Capacitances

    Page(s): 642 - 648
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    A new algorithm is presented for the calculation of TEM parameters of microstrips, based on a lumped-circuit model of the microstrip transverse static field. The use of such an algorithm allows one to obtain either very high accuracies or very low computer times when ordinary accuracies are tolerated. Compared with the similar technique by Lennartsson, the analysis method presented here allows substantial reduction in computer time, storage, and errors. View full abstract»

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  • Prototype Characteristics for a Class of Dual-Mode Filters (Short Papers)

    Page(s): 708 - 711
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    Selected prototype characteristics of nonequiripple antimetric elliptic-function filters which can be realized in orthogonal cascaded dual-mode circular or square waveguide structures are presented. Cavity-coupling data for 4-, 6-, and S-section 0.01- and 0.05-dB-ripple passband designs with variable stopband levels are tabulated. Quantitative comparisons of elliptic and Chebyshev filter designs are also discussed, indicating the superior characteristics of elliptic networks. View full abstract»

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  • Low-Noise Design of Microwave Transistor Amplifiers (Short Papers)

    Page(s): 697 - 700
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    Parameters are derived for circles of constant overall noise figure on the source admittance plane of a preamplifier cascaded with a noisy main amplifier. It is shown that the noise figure and noise measure of an amplifier can be expressed in terms of the scattering parameters of a lossless two-port network connected at the input of the amplifier. Examples are given which demonstrate how this network can be synthesized to meet amplifier noise specifications. View full abstract»

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  • Analytic Constraints on Electromagnetic Field Computations

    Page(s): 605 - 623
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    It is attempted to provide a defintive statement of the theoretical bases and the computationally useful manifestations of integral equation formulations of field problems, and the expansion of fields in sequences of functions which are proper solutions of the wave equation. The reason for doing this is that it has become clear during the last ten years that sophisticated points of mathematical analysis have practical computational significance. For ease of exposition, only two-dimensional fields are treated in detail. The paper is in five parts. The first part (Sections I and II) is introductory. The second part (Sections III-V) deals with formal diffraction theory. Methods particularly suited to digital computation are presented in the third part (Sections VI-XI). The results of computational experience are assessed in the fourth part (Sections XII-XIV). The fifth part (Sections XV-XVII) discusses the types of investigation needed to increase the technological usefulness of existing techniques. View full abstract»

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  • An Alternate Derivation and Procedure for Cristal's Transformation for Transmission-Line Networks (Letters)

    Page(s): 715 - 716
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    This letter gives an alternate derivation and procedure for Cristal's transformation which transforms commensurate transmission-line networks with unit elements from the frequency variable lambda to 1/lambda, where lambda = tanh(lambda L). View full abstract»

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  • Design and Performance of X-Band Oscillators with GaAs Schottky-Gate Field-Effect Transistors

    Page(s): 661 - 667
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    The circuit construction and design of an X-band oscillator with a GaAs Schottky-gate FET have been studied. The oscillation characteristics including stability and noise performance have been examined in order to clarify the position of a GaAs FET as a microwave solid-state oscillator device. The experiments have revealed that 1) the GaAs FET simultaneously possesses the most desirable features of both Gunn and IMPATT oscillators, i.e., low bias voltage operation and fairly high efficiency, and 2) it is situated between Gunn and GaAs IMPATT oscillators with respect to noise properties. The results indicate that the GaAs FET oscillator will soon be joining the family of microwave solid-state oscillators as a promising new member. View full abstract»

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  • Temperature-Stabilized 1.7-GHz Broad-Band Lumped-Element Circulator

    Page(s): 689 - 696
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    A new construction technique for broad-banding and temperature stabilization of a lumped-element circulator is presented to obtain a compact circulator for practical usage. By using a new integrated wide-banding network consisting of three series resonant circuits on the back of the junction substrate, 1.7-GHz double-tuned and triple-tuned broad-band circulators have been successfully developed. Fundamental junction parameters, such as an in-phase eigeninductance, parasitic capacitance, and nonreciprocal filling factor, have been investigated experimentally. A design theory for temperature compensation of a lumped-element circulator is also presented, and temperature compensation with bias magnetic field of postitive temperature coefficient has been applied to the 1.7-GHz broad-band circulators. As a result, 20-dB isolation bandwidths of more than 600 MHz (double-tuned type) and 950 MHz (triple-tuned type) have been obtained throughout the temperature range of -10 ~ +60°C. 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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