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Microwave Theory and Techniques, IEEE Transactions on

Issue 7 • Date Jul. 1972

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Displaying Results 1 - 13 of 13
  • [Front cover - July 1972]

    Publication Year: 1972 , Page(s): f1 - f2
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    Freely Available from IEEE
  • Contributors, Jul. 1972

    Publication Year: 1972 , Page(s): 491 - 492
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    Freely Available from IEEE
  • [Back cover]

    Publication Year: 1972 , Page(s): b1 - b2
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    Freely Available from IEEE
  • Elastic Waves Guided by a Solid Layer Between Adjacent Substrates

    Publication Year: 1972 , Page(s): 477 - 486
    Cited by:  Papers (5)
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    The present investigation is motivated by the problem of coupling Rayleigh waves between adjacent substrates when either substrate is nonpiezoelectric, in which case it becomes necessary to resort to some mechanical means to achieve this coupling. The use of a fluid coupling layer has been investigated and experimentally demonstrated elsewhere, while the use of a solid layer, with its inherently greater mechanical stability, has also been proposed. In this work, the operating characteristics of a specific solid-layer structure are predicted on the basis of a theoretical analysis, which furnishes the propagation characteristics and field structure of the waves which may be guided by a solid layer between two identical solids. View full abstract»

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  • Broad-Band Coupling to High-Q Resonant Loads

    Publication Year: 1972 , Page(s): 453 - 458
    Cited by:  Papers (15)
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    Broad-band coupling between a resistive source and a resonant load is considered for coupling networks consisting of a uniform transmission line of impedance ZI and length equal to a quarter wavelength at the load resonant frequency. An approximate analysis is used to show that either maximally flat or ripple insertion loss frequency response can be obtained by proper choice of ZI, and the 3-dB bandwidth obtained in either case is always greater than 1/Q. Depending on the ratio of load and source resistances, the bandwidth may be greater than 1 octave. Network design curves for maximally flat operation with a variety of load parameters are computed without approximation. The design of lumped element approximations for the transmission line network is also described. View full abstract»

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  • Stripline Triplexer for Use in Narrow-Bandwidth Multichannel Filters (Short Papers)

    Publication Year: 1972 , Page(s): 486 - 488
    Cited by:  Papers (2)
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    Design techniques and equivalent circuits are presented for constructing a printed-circuit narrow-bandwidth complementary triplexer filter. The techniques and circuits described allow the construction of contiguous-band multichannel filters using printed circuits with no shorted stubs. A unit was designed and constructed to give a three-percent relative bandwidth for each separate channel. The agreement between theory and experiment was in the range of measurement accuracy. View full abstract»

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  • Experimental Evaluation of Noise Parameters in Gunn and Avalanche Oscillators

    Publication Year: 1972 , Page(s): 425 - 437
    Cited by:  Papers (15)
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    Equations are presented that express noise-to-carrier ratio and rms frequency deviation of a negative-resistance oscillator with a multiple-resonant circuit in terms of effective available noise power densities of both 1/f and white-noise sources, an effective saturation factor, and an appropriate QL of the oscillator. Experimental evaluation of the noise parameters in Gunn and avalanche oscillators by use of these equations is described. AM and FM noise measurements have been made on X-band Gunn oscillators and Si and GaAs avalanche oscillators for frequency off carriers extending from 1 kHz to 10 MHz. Both 1/f and white noise have been observed in these oscillators. The validity of the above equations has been verified for Gunn oscillators from the dependence of the noise spectra on QL. For Gunn oscillators and Si and GaAs avalanche oscillators, the effective noise-temperature ratio for white noise, N/kT0, has been found to be 23~29, 41~51, and 38~44 dB, and the effective saturation factor to be 2~2.9, 0.5~2.4, and 2, respectively. An increase of N/kT0 with the RF voltage across the diode has been observed in Si avalanche oscillators. Parameters for 1/f noise have also been evaluated approximately. View full abstract»

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  • An Improved Equivalent Circuit for the Thin-Film Lumped-Element Circulator

    Publication Year: 1972 , Page(s): 446 - 452
    Cited by:  Papers (8)
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    A program written for the Hewlett-Packard automatic network analyzer permits the S-parameter eigenvalue phases and magnitudes to be displayed. The thus measured eigenvalues of a lumped-element circulator lead to an improved equivalent circuit which explains the observed "double hump" characteristic. The influence of different circuit parameters on the eigenvalues is measured and found in good agreement with the author's previously published theory. It is concluded from this theory and the measurements that, for the lossy circulator in general, maximum isolation, return loss, and minimum forward loss do not occur at the same frequency. View full abstract»

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  • Tapping of Love Waves in an Isotropic Surface Waveguide by Surface-to-Bulk Wave Transduction

    Publication Year: 1972 , Page(s): 472 - 477
    Cited by:  Papers (4)
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    A theoretical study of tapping a Love wave in an isotropic microacoustic surface waveguide is given. The surface Love wave is tapped by partial transduction into a bulk wave at a discontinuity. It is shown here that, by careful design of the discontinuity, the converted bulk wave power and the radiation pattern may be controlled. General formulas are derived for the calculation of these important characteristics from a relatively general surface contour deformation. View full abstract»

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  • Permeability Tensor of Magnetized Ferrites from Waveguide Measurements (Computer Program Descriptions)

    Publication Year: 1972 , Page(s): 490 - 491
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    By means of this program the complex eigenvalues of the permeability tensor of magnetized ferrites can be calculated from measurements of the propagation constants of right- and left-handed rotating HE11 waves in circular cylindrical waveguides containing axial longitudinally magnetized ferrite rods. View full abstract»

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  • Analysis and Design of Dispersive Interdigital Surface-Wave Transducers

    Publication Year: 1972 , Page(s): 458 - 471
    Cited by:  Papers (94)  |  Patents (3)
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    A comprehensive circuit model characterization of dispersive interdigital transducers with nonuniform electrode spacing is presented. The model is an extension of a three-port circuit which has been useful for representing periodic transducers. The extended model includes the effects of strong piezoelectric coupling whereby the acoustic waves and electric circuits interact, and it also accounts for reflections of acoustic waves which result from perturbations of the crystal surface by the metal electrodes. The inclusion of the latter effect is shown to be essential for explaining observed levels of triple-transit echos in filters and delay lines. The circuit model is used to derive a transducer design procedure which determines the electrode positions and the anodization function (acoustic aperture taper) required to reproduce a desired waveform. This procedure is applicable to the design of weighted dispersive filters and broad-band nondispersive delay lines. In order to verify the theory a low-loss octave-bandwidth nondispersive delay line was designed using linear FM dispersive transducers on YZ LiNbO3. The performance of this device was found to be in good agreement with the circuit model predictions. View full abstract»

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  • First-Order Nonlinear Theory in Hexagonal Ferrites with Planar Anisotropy under Perpendicular Pumping

    Publication Year: 1972 , Page(s): 437 - 446
    Cited by:  Papers (1)
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    The first-order spinwave instability under perpendicular pumping at large signal power in an hexagonal ferrite ellipsoid with planar anisotropy biased in the easy plane is studied. The nonlinear coupling coefficient is obtained in terms of the physical variables of the unstable spinwaves and the uniform mode magnetization such as the orientation and ellipticity of the unstable spinwaves, the coordinates of the spinwave propagation vector k, and the uniform mode ellipticity. Results obtained using a computer in the case of a sphere are included. Also included are experimental results on the coincidence region with the dc field in the easy plane and with the dc field out of the easy plane. This latter arrangement leads to a new tunable coincidence limiter. View full abstract»

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  • Implementation of Conservation-of-Energy Condition in Small Aperture and Small Obstacle Theory (Short Papers)

    Publication Year: 1972 , Page(s): 488 - 490
    Cited by:  Papers (1)
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    In a previous paper, Felsen and Kahn showed that the scattering matrix of small apertures and obstacles in multimode waveguide regions is conveniently calculated for general lossless structures, but observed that the scattering matrix does not satisfy the conservation-of-energy requirement. It is also to be noted that the scattering parameters could become much larger than unity or even infinite for frequencies near or at the cutoff of the coupled modes. A method is presented in this correspondence to implement the lossless condition so that the resultant scattering matrix satisfies the conservation-of-energy requirement and, consequently, can be represented as a Iossless equivalent circuit for all frequencies. The corresponding impedance, admittance, and transfer matrices for general lossless symmetrical structures are given in compact form directly in terms of the scattering parameters. View full abstract»

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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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