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Microwave Theory and Techniques, IEEE Transactions on

Issue 10 • Date Oct. 1983

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Displaying Results 1 - 17 of 17
  • [Front cover - Oct. 1983 Transactions]

    Publication Year: 1983 , Page(s): f1 - f2
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    Freely Available from IEEE
  • Nonlinear Theory of Parametric Oscillator: Steady-State Operation and Fluctuation Analysis

    Publication Year: 1983 , Page(s): 797 - 805
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (770 KB)  

    Parametric oscillators with a superconducting output cavity are of great interest as sources of very high frequency stability. In this paper, a careful analysis is performed for a parametric oscillator model based on an abrupt junction varactor with fixed-bias voltage and ideal shunt mode operation. Steady-state operation, transfer functions for amplitude and phase fluctuations, and additive noise contributions are examined. An overall estimation of system performance as regards to the phase instabilities shows that although the foreseen characteristics are Iess outstanding than expected from a previously reported analysis, this device compares favorably with the most important available sources based on atomic transitions or on superconducting cavity-stabilized oscillators. View full abstract»

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  • Single-Post Inductive Obstacle in Rectangular Waveguide

    Publication Year: 1983 , Page(s): 806 - 812
    Cited by:  Papers (81)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (818 KB)  

    A rapidly converging moment solution for electromagnetic scattering by a single inductive post in a rectangular waveguide is obtained. The numerical results show good agreement with Marcuvitz's data as far as this data goes. Furthermore, Marcuvitz's curves are extended to cover data for large posts. This new data should aflow one to design a simply constructed new type of narrow bandpass filter, namely, a filter consisting of large single posts. The successful use of this straightforward moment solution in solving the single-post problem suggests that this technique should prove useful in solving a variety of microwave discontinuities such as those involving thin or thick irises and posts of arbitrary shape. View full abstract»

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  • Optical Control of GaAs MESFET's

    Publication Year: 1983 , Page(s): 812 - 820
    Cited by:  Papers (76)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1014 KB)  

    Theoretical and experimental work for the performance of GaAs MESFET's under illumination from light of photon energy greater than the bandgap of the semiconductor is described. A simple model to estimate the effects of light on the dc and RF properties of MESFET'S is presented. Photoconductive and photovoltaic effects in the active channel and substrate are considered to predict the change in the dc equivalent circuit parameters of the FET, and from these the new Y- and S-parameters under illumination are calculated. Comparisons with the measured S-parameter's without and under illumination show very close agreement. Optical techniques can he used to control the gain of an FET amplifier and the frequency of an FET oscillator. Experimental results are presented showing that the gain of amplifiers can be varied up to around 20 dB and that the frequency of oscillators can be varied (tuning) around 10 percent when the optical absorbed power in the active region of the FET is varied by a few microwatts. When the laser beam is amplitude-modulated to a frequency close to the free-running FET oscillation frequency, optical injection locking can occur. An analytical expression to estimate the locking range is presented. This shows a fair agreement with the experiments. Some suggestions to improve the optical locking range are presented. View full abstract»

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  • Balance Quality Measurements on Baluns

    Publication Year: 1983 , Page(s): 821 - 824
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (990 KB)  

    Two different methods of measuring the balance quality of baluns are described. Section I describes the balance comparator, a mechanical test device requiring only a signal source, and receiver to perform the measurements on the test balun. Section II describes the use of a network analyzer, computer controlled to plot out all the graphical data on the balun measurements. Measurements on a balun having known balance characteristics show both methods obtain satisfactory balance data. View full abstract»

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  • A Study of the Filter Properties of Single and Parallel-Coupled Dielectric-Waveguide Gratings

    Publication Year: 1983 , Page(s): 825 - 835
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1196 KB)  

    Our work with gratings in dielectric image guide shows that it is distinctly advantageous to place the grating notches on the sides of the guide, or on the top of the guide, depending on the mode used. Means are discussed for modeling gratings using an equal-line-length transmission-line equivalent circuit. Excellent agreement between computed and measured bandstop frequency responses of gratings are obtained. Design relations for gratings are presented, and equations for analysis and design of parallel-coupled grating structures are derived. It is shown that a simple bandpass filter can be made from properly designed parallel-coupled gratings with distributed loads at one end. It is also shown that by use of combinations of parallel-coupled and direct-coupled gratings, multiresonator filters with Chebyshev or other characteristics can be obtained. Experimental results in agreement with computed responses are demonstrated. View full abstract»

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  • Optimum Sectional Shape of Dominant Mode Waveguide

    Publication Year: 1983 , Page(s): 836 - 841
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (782 KB)  

    Approximating the cross section of a waveguide by a truncated Fourier series and using the finite element method (FEM), together with the quasi-Newton optimization method, the optimum cross section of the dominant mode waveguide which has minimum conductor loss is obtained. We take the attenuation constant at the cutoff freqnency of the second higher mode as the index of good quality. This index simplifies the computation and gives a unique solution. The obtained optimum cross section is a kind of cigar shape. The Fourier series converges quite quickfy, supporting the reliability of the numerical results. This optimum cross section gives 9.4-percent smaller conductor loss than, and the same frequency bandwidth as, the standard rectangular cross section. The theoretical results are confirmed by measurements. View full abstract»

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  • An Accurate Approximation of the Impedance of a Circular Cylinder Concentric with an External Square Tube

    Publication Year: 1983 , Page(s): 841 - 844
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (437 KB)  

    The problem of determining the characteristic impedance of a concentric coaxial transmission line having a circular inner conductor and a square outer conductor is reexamined. The Green's function for a rectangle is used to determine the geometrical capacitance of a series of structures ranging from 1-46 Omega with an error less than 10 -5. The method of analysis is illustrated in detail for the 1-Omega case. The resitlts are presented in terms of the "outer shield factor" R eff, which is defined as the ratio of the diameter of an outer circle, having the same capacitance as the outer square, to the side of the outer square, Values of this ratio are tabulated for impedances ranging from 1-46 Omega. These values are also plotted on a curve which can be read with an error of the order of 0.02 Omega for impedances greater than 3 Omega. View full abstract»

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  • Theoretical and Experimental Study of the Resonant Frequency of a Cylindrical Dielectric Resonator

    Publication Year: 1983 , Page(s): 844 - 848
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB)  

    A rigorous modal method is described for calculating the resonant frequencies of a circular cylindrical dielectric rod placed between two perfectly conducting plates. Comparisons of the numerical results with those obtained from another rigorous theory developed at the same time by one of the authors show an accuracy better than 10 -4. Comparison with experimental data shows generally a very good agreement. View full abstract»

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  • Moment-Method Solutions and SAR Calculations for Inhomogeneous Models of Man with Large Number of Cells

    Publication Year: 1983 , Page(s): 848 - 851
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (443 KB)  

    This paper describes an iterative band approximation method (BAM) that is useful for solution of large matrix eqnations where the elements of the matrix decrease in magnitude with increasing distance from the diagonal. The method involves the inversion of a band about the diagonal which is nsed to obtain a first estimate of the solution. This estimate, along with the remaining elements in the matrix above and below the band, is used to iterate to the final solution. Due to the substantial reduction in the size of the matrix which is actually inverted, the method has been applied to the solution of full complex matrix equations involving up to 1698 unknowns. BAM is used to obtain distributions of EM energy absorption for man models with 180-1132 cells. View full abstract»

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  • Comments on "Capabilities of Multi-Applicator Systems for Focused Hyperthermia"

    Publication Year: 1983 , Page(s): 851 - 852
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (223 KB)  

    In the above paper, the author has incorrectly assumed that aperture size must be limited to a lateral dimension of not less than one wavelength in fat tissue in order to prevent excessive heating of superficial fat. The reference cited to support this conclusion [1] did not make such a generalization, but rather provided an example which implied this restriction at a particular frequency and with a certain aperture size. In actually, however, focussed co-phased applicators are useful across a much broader range than Knoechel has suggested. View full abstract»

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  • Comments on "Refraction at a Curved Dielectric Interface Geometrical Optics Solution"

    Publication Year: 1983 , Page(s): 853
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    In the above paper, Lee et al. consider the refraction of waves at a curved dielectric interface between media of uniform refractive index. They quote an earlier paper by us [2], and infer that our results are either inadequate or incorrect. We should like to have the opportunity to state that we have no reason to doubt the validity of our results, which. in any case were independently verified by Jones [3], and to point out how the erroneous conclusions of Lee et al. arise. View full abstract»

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  • Patent abstracts

    Publication Year: 1983 , Page(s): 854 - 856
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB)  

    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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  • Asian abstracts

    Publication Year: 1983 , Page(s): 856 - 869
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    Freely Available from IEEE
  • [Advertisement]

    Publication Year: 1983 , Page(s): 870
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    Freely Available from IEEE
  • [Advertisement]

    Publication Year: 1983 , Page(s): 872
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    Freely Available from IEEE
  • [Back cover - Oct. 1983 Transactions]

    Publication Year: 1983 , Page(s): b1 - b2
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    Freely Available from IEEE

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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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