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Microwave Theory and Techniques, IRE Transactions on

Issue 6 • Date November 1961

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Displaying Results 1 - 25 of 35
  • [Front cover - Nov. 1961 [T-MTT]]

    Page(s): f1 - f2
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    Freely Available from IEEE
  • Index, IRE Transactions on Microwave Theory and Techniques, Volume MTT-9, 1961

    Page(s): i - v
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    Freely Available from IEEE
  • Table of contents (Nov. 1961 [T-MTT])

    Page(s): 457
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  • Microwave Prize

    Page(s): 458
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  • Passive Phase-Distortionless Parametric Limiting with Varactor Diodes

    Page(s): 459 - 472
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    The theory of passive parametric limiting with a varactor diode as the nonlinear element is developed and verified experimentally. The limiting is found to be flat and phase-distortionless. Expressions are given for threshold level, dynamic range, bandwidth, and power dissipation. The transient phenomena, comprising leading- and trailing-edge leakage spikes, are studied theoretically and experimentally, and found to be small in typical instances. Experimental results reported upon include a simple waveguide limiter structure at S band; a lumped-circuit limiter at 126 Mc; and a strip-line limiter using a pill varactor at S band. The latter has an insertion loss of 2.5 db below threshold, a threshold level of 2 mw, a dynamic range in excess of 20 db, and less than 5° of phase distortion. Agreement between theory and experimental results is excellent. View full abstract»

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  • Solid-State X-Band Power Limiter

    Page(s): 472 - 480
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    An X-band solid-state power limiter has been designed and built to protect receiver crystals from high-power microwave pulses in the kilowatt region. This passive and reliable crystal protection has been achieved by utilizing the nonlinear properties of both ferrites and semiconductor diodes. An understanding of the ferrite nonlinear mechanism, which gives rise to the characteristically large leakage spike, has been achieved and quantitatively described. This formulation resulted in an essentially optimized high-power ferrite limiter, whose mode of operation is qualitatively understood. Use of this ferrite limiter for crystal protection requires a fast response, lower threshold secondary-limiting unit, which was developed by using semiconductor diodes for power limiting in a reactive mode of operation. The ferrite and diode limiters were combined in a single device with an over-all insertion loss of 2.0 db and a 200-Mc operating "bandwidth." View full abstract»

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  • On Spurious Outputs from High-Power Pulsed Microwave Tubes and Their Control

    Page(s): 480 - 484
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    Excessive spurious outputs from high-power pulsed magnetrons, klystrons and traveling-wave tubes can cause intolerable interference and deleterious effects in a high-power microwave system. The harmonic output from a klystron may vary appreciably with changes in operating conditions. Harmonic outputs from tubes cannot be eliminated but their radiation can be significantly reduced by using filters. If the parasitic or spurious oscillations are very strong, adverse effects such as amplitude and phase instability of the fundamental frequency output may occur. Some of the spurious outputs may be reduced or eliminated by redesign of the tube or its modulator. View full abstract»

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  • Practical Design and Performance of Nearly Optimum Wide-Band Degenerate Parametric Amplifiers (Nov. 1961 [T-MTT])

    Page(s): 484 - 490
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    The design of a two-resonator single-diode degenerate parametric amplifier is described, which incorporates features that give it nearly optimum wide-band performance. These features include the use of almost lumped circuit elements, a separate pump resonator which is very lightly coupled to the diode and pump circuits, and a diode resonated in series rather than in shunt, from which several advantages accrue. A bandwidth of 21 per cent with 15-db midband gain (double channel) is obtained at 1 Gc using two resonators, as compared with 8 per cent using one resonator. Both measured responses are found to be in excellent agreement with theoretical responses obtained with a digital computer. The measured double-channel noise figure was 1 db. Theoretical and experimental results are presented which show this type of amplifier to be remarkably insensitive to tuning errors. Good results were also obtained using two identical amplifiers in balanced operation with a 3-db coupler so as to eliminate the need for a circulator. View full abstract»

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  • Transmission-Phase Relations of Four-Frequency Parametric Devices

    Page(s): 491 - 498
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    The gain, bandwidth, and excess noise temperature properties of parametric amplifiers are generally known. However, a knowledge of their transmission-phase properties is also essential for the effective application of parametric amplifiers to angular detection systems, such as monopulse radars and interferometers. These angle detection systems derive even, odd, and quadrupolar spatial components of the antenna diffraction patterns. The differential amplitude and differential phase between these signal components contain the spatial information of position, extent, and shape of the target. Consequently, to employ parametric transducers in certain systems requires an understanding of the transmission phase properties which are delineated in this paper. The analysis follows the matrix representation of a nonlinear capacitive susceptance, four-frequency transducer wherein due note is taken of the phases. The transmission-phase relations are written which include the effects of nonzero port susceptance and nonlinear reactance element losses. At midband without losses, the relations reduce to easily remembered equations which are significant to the application of parametric transducers in phase-sensitive systems. Some applications and experimental results are cited. View full abstract»

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  • A Plasma Guide Microwave Selective Coupler (Nov. 1961 [T-MTT])

    Page(s): 499 - 506
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    A new type of microwave coupler has been investigated in the X-band and S-band ranges. In this coupler, a gas discharge tube passes through two rectangular waveguides that are separated by some distance. A metal cylinder surrounds the discharge tube in the separation space. The coupling of microwave power via this plasma guide coupler can be varied electronically over a range greater than 30 db. Pulsed power levels of more than 100 w can be handled. When operated as a switch, a switching time of from 2 to 5 µsec has been observed. This paper describes some of the operating characteristics that have been observed, an approximate theory of operation, and measurements pertinent to a complete description of the coupler. View full abstract»

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  • High-Power Duplexers

    Page(s): 506 - 512
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    The various circuit arrangements used in duplexers are analyzed in terms of their power-handling ability in two situations: first, where the bandwidth is narrow so that insertion loss determines maximum Q, and second, where large bandwidths are required and the maximum Q is determined by available Q band-width products. In both cases the ATR duplexer has an advantage. Arc loss was measured for folded cylinder TR tubes. At medium current densities the results agree well with experimental measurements in dc positive columns. At high current densities a constant conductivity is reached. Graphs of power-handling ability for a unity coupler duplexer using different methods of cooling are presented. It is shown that the requirements for easy firing and long life limit the achievable recovery time. View full abstract»

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  • Quasi-Optical Surface Waveguide and Other Components for the 100- to 300-Gc Region

    Page(s): 512 - 518
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    Components and techniques for the generation, transmission, and detection of energy in the 100- to 300-Gc frequency region were investigated theoretically and experimentally. The design and construction of fundamental components, such as harmonic generators and detectors, were necessary since many items are not available commercially. A detailed theoretical analysis was performed for the propagation characteristics of single-conductor transmission lines, and attenuation calculations were made for several dielectric image lines. Experimental measurements were made at 105 and 140 Gc on these two types of surface waveguides. Attenuation of these lines is compared with that of dominant-mode rectangular waveguide. An analysis of phase-correcting Fresnel zone plates was carried out, and several zone plates were designed, constructed and successfully tested at frequencies of 140, 210, and 280 Gc. Zone plates were used at several frequencies to make relatively long path transmission measurements and were also used in a specially designed Michelson interferometer. The frequency stability of the source klystron and the dielectric properties of a number of plastic materials were determined by measurements made with the interferometer. A method of frequency filtering by focal isolation was demonstrated with this equipment. View full abstract»

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  • Broad-Band Isolators and Variable Attenuators for Millimeter Wavelengths

    Page(s): 519 - 523
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    A longitudinally magnetized rod of ferrite has been used as a dielectric waveguide which provides Faraday rotation independent of frequency in the band from 50 to 60 kMc. This rotator has been incorporated into broad-band isolators with forward losses of 1 db and reverse losses greater than 30 db with return losses of approximately 20 db over the band. It has also been used in a variable attenuator with a minimum loss of 1 db and a maximum loss greater than 30 db which is essentially constant over the band. Advantages of this type of rotator at millimeter wavelengths include bandwidths in excess of 20 per cent, low field requirements (25-50 œ), relatively large dimensions, the use of common ferrites, and the absence of conducting waveguide walls which permits rapid switching of the control field. The last feature has been utilized in an automatic power leveling system capable of removing variations of several kc frequency content from the swept output of a millimeter wave BWO. View full abstract»

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  • A New High-Precision Method for the Measurement of the VSWR of Coaxial Connectors

    Page(s): 524 - 528
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    A substitution method of measuring the very small reflections due to a pair of precision coaxial connectors has been developed. The connectors under test are mounted on a section of precision air line which serves as the impedance reference standard. The electrical length of this line, including connectors, is a multiple of one-half wavelength at the frequency of measurement. A slotted line and a termination, both having the same type connectors as those under test, are required. With the aid of an auxiliary slide-screw tuner, the slotted line and the termination are matched to each other. The output of the slotted line is then plotted by a graphic level recorder having an expanded-scale presentation and a mechanical linkage between the chart drive and the probe on the slotted line. The section of air line fitted with the connectors under test is then placed between the slotted line and the termination, and a second curve is recorded. The slotted line and termination errors still cancel each other, and any errors due to variations in probe coupling along the line also cancel out. The difference between the initial curve and the second curve represents the mismatch of the connectors under test with respect to the precision air line. With a recorder having a scale expansion of 2 per cent full scale, VSWR's as low as 1.001 are easily discernible. View full abstract»

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  • Hybrid-Ring Directional Coupler for Arbitrary Power Divisions

    Page(s): 529 - 535
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    A directional coupler in the form of a hybrid ring is described in this paper. A theoretical analysis using the scattering matrix has been carried out and experimental verification of the theoretical result has been achieved in a stripline network. Simple design equations which enable one to design a directional coupler with any degree of coupling have been derived. This coupler differs from the commonly used couplers in that the voltages at the output arms are either in-phase or opposite-phase with respect to each other. In addition, its geometrical symmetry makes it very convenient for use in symmetrical networks, particularly as a power divider in antenna feeding systems. View full abstract»

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  • A Coupled Strip-Line Configuration Using Printed-Circuit Construction that Allows Very Close Coupling

    Page(s): 535 - 544
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    A new strip-line configuration is presented, applicable to printed-circuit construction, that allows very close coupling to be achieved without esorting to very small coupling gaps and excessively critical dimensions. Graphs of even- and odd-mode fringing capacitances are given. These graphs can be used with simple formulas, which also are given, to determine the dimensions of the configuration that will give specified even- and odd-mode characteristic impedances or shunt capacitances. The usefulness of the graphs and formulas was demonstrated by using them to design 3-db backward-couplers. The performance of the couplers in this new configuration was typical of similar couplers made in more conventional configurations, as expected. However, the devices shown have an advantage in that they can be manufactured by relatively inexpensive and rapid printed-circuit methods and, since the region between the conductors is solid dielectric, they are unusually rugged. View full abstract»

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  • The Measurement of Conductivity and Permittivity of Semiconductor Spheres by an Extension of the Cavity Perturbation Method

    Page(s): 545 - 551
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    A technique based on cavity perturbation theory is described with which one can determine the microwave conductivity and dielectric permittivity of a small sphere of completely arbitrary conductivity. These properties follow from the measured frequency shift and quality change occurring when the sample is inserted into a region of maximum electric field in a cavity resonator. The range of validity of the quasi-static internal field approximation is discussed, and curves are provided for extending the measuring technique beyond this range. The extended theory is valid for the entire conductivity range from zero to infinity. Measurements on several samples of known conductivity and permittivity in which the approximation is not satisfied are seen to agree with the theory. For highly conductive materials, the present method is closely related to the "eddy current loss" measuring technique discussed by others. The two methods are compared from the point of view of perturbation theory in order to determine their relative merits. Because the measuring technique employs a spherical sample, it may be applied profitably to materials with nonisotropic carrier nobilities and to semiconducting materials for which contact fabrication techniques are poorly known. View full abstract»

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  • The Dominant Cutoff Wavelength of a Lunar Line

    Page(s): 552 - 556
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    A method is presented for calculating the lowest cutoff wavelength of a new microwave transmission line, the "lunar line," which is formed by two eccentric circular metal tubes connected with a metal bar or tangential to each other. The lunar-shaped cross section is approximated by introducing a series of steps in the outer guide wall and by dividing the cross section into m fan-shape regions. Thus, the problem is reduced to one of a multiple-step waveguide and can be solved by introducing the angular parameter alphai for the individual regions. The radial boundary conditions require a combination of Bessel functions of noninteger order for each region. The common boundaries between regions give m integral equations that represent the total power in one region transferred into the next region. The integral equations are solved approximately by solving only the first terms of an infinite series expansion of the tangential electric field at the common boundary. The solution of the m-stepped waveguide results in a system of 2m equations containing 2m unknowns: the cutoff wave number betac, the order of the Bessel function pi, and the angular parameter alphai. A successive approximation method is applied to obtain the cutoff wavelength. The calculated value is in close agreement with experimental results. View full abstract»

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  • The Negative-Conductance Slot Amplifier

    Page(s): 557 - 566
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    It has been suggested that the incorporation of active solid-state devices into the elements of an antenna may lead to the simplification of the over-all microwave system and at the same time to a reduction in size, power and weight requirements. This paper will discuss several approaches to a study of the microwave properties of a slotted antenna element shunted by a tunnel diode biased into its negative-conductance region. The first approach involves calculation of the lumped parameter equivalent circuit of the slot amplifier system at resonance and can be extended to determination of the gain bandwidth and noise performance of the device, whereas the second approach is concerned with the admittance of the slot and the diode as a function of frequency over a wide frequency range. The latter method of analysis successfully predicts the conditions of oscillation and amplification at fundamental as well as higher frequency resonances and leads to a method for stabilization of the system. Preliminary experimental results indicate a transmission gain of 21.5 db at 2.7 kMc with a Hughes Number PC-3 GaAs tunnel diode in the slot amplifier. View full abstract»

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  • Measurement of the Conversion Conductance of Esaki Mixer Diodes (Correspondence)

    Page(s): 567 - 568
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    In order to compare the theoretically predicted and the experimentally observed behavior of frequency converters using Esaki diodes, it is necessary to evaluate various mixer parameters, in particular, the conductance elements of the conversion matrix. It is well known, these conductance elements are certain Fourier coefficients of the periodic series representing the incremental time-varying diode conductance. This conductance is produced by the large local oscillator (LO) voltage acting on the non-linear diode. Although one can determine these element values using a numerical Fourier analysis, this approach is both time-consuming and laborious. As an alternative, we suggest an experimental technique originally proposed by Dicke over ten years ago for use with conventional (positive-conductance) crystal mixer diodes. Since this method is quite easy to apply in that it only involves several low-frequency bridge measurements and one standing-wave measurement, and since, apparently, it is not well known, we shall risk repetition by describing a simplified version of it which we have modified to apply to Esaki diodes. View full abstract»

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  • A Versatile Phase Measurement Method for Transmission-Line Networks (Correspondence)

    Page(s): 568 - 569
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    Current phase-measurement methods for transmission-line circuits fall into two general categories. The first is the comparison method, where the path under measurement is compared with another calibrated, variable one. The phase shift through the variable path is adjusted to equal that of the unknown path, and this condition is shown by a null detector. Null indication by both phase and amplitude adjustment is usually required; however, null indication by phase adjustment alone can be effected. The second category of phase measurements includes those measurements which provide voltage or meter output indication of phase angle. This category includes direct high frequency phase-dectector circuits of limited frequency phase-dectector circuits of limited frequency range or frequency-conversion methods where analog or digital circuits measure phase at a converted lower frequency. View full abstract»

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  • A VHF High-Power Y-Circulator (Correspondence)

    Page(s): 569 - 570
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    A number of articles on the theory, design and application of three-port circulators may be found in the literature. Specific devices of this kind are commercially available for low signal power levels. In this letter a high-power version of a three-port or V-circulator k presented. The charcteristics measured at high power are compared with measurements performed at low power. View full abstract»

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  • N-Terminal Power Divider (Correspondence)

    Page(s): 571
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    Recently Wilkinson has described an N-way hybrid power divider which decouples the outputs. View full abstract»

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  • 10-DB XL Cross Guide Coupler (Correspondence)

    Page(s): 571
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    Two interesting points were noted while working with half-height cross guide couplers. The first was that if the same size coupling holes were used as in the full size waveguide, coupling was increased approximately 3 db. The second, and more important, was that the value of coupling was much more constant over a given frequency band, with essentially no change in directivity. View full abstract»

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  • Design Note on an L-Band Strip-Line Circulator (Correspondence)

    Page(s): 571 - 572
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    The technique of using magnetized yttrium-iron-garnet slabs in dielectrically-loaded strip transmission Iine as the reciprocal elements in a UHF and low-microwave frequency, 4-port circulator has been demonstrated most effectively by Arams, et al. This communication reports the results of an independent and concurrent development program at our laboratory which led to a similar L-band circulator using a some what different configuration. View full abstract»

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Aims & Scope

This Transactions ceased publication in 1962. The current retitled publication is IEEE Transactions on Microwave Theory and Techniques.

Full Aims & Scope