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Microwave Theory and Techniques, IRE Transactions on

Issue 4 • Date October 1958

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  • [Front cover - Oct. 1958 [T-MTT]]

    Page(s): f1 - f2
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    Freely Available from IEEE
  • Index, IRE Transactions on Microwave Theory and Techniques, Volume MTT-6, 1958

    Page(s): i - v
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    Freely Available from IEEE
  • Table of contents (Oct. 1958 [T-MTT])

    Page(s): 339
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    Freely Available from IEEE
  • Biography - Eugene G. Fubini

    Page(s): 340
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    Eugene G. Fubini (A'36-SM'46-F'54) was born on April 19, 1913 in Turin, Italy. He received the Ph.D. degree from the University of Rome, Italy, in 1933. Associated with the National Electric Institute of Italy from 1936 to 1938, he also worked prior to World War I, in the Short-Wave Division, General Engineering Department, of the Columbia Broadcasting System. View full abstract»

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  • A Plea for Simplification

    Page(s): 341 - 342
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    Handbook engineering is becoming more and more common in our laboratories and the distance is increasing between the engineer faced with the practical problem and the professional theoretical man. The widening of the practice-theory gap seems to be universal throughout our industry: our efficiency is reduced and progress made more difficult. The people who are compelled to the steady use of hand-book formulas regret this fact and have an intense thirst for knowledge. View full abstract»

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  • Microwave Prize (Oct. 1958 [T-MTT])

    Page(s): 343
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    The Professional Group on Micvowave Theory and Techniques has established the microwave Prize to recognize annually a significant paper which appeared in the IRE Transactions on Microwave Theory and Techniques. In selecting the paper, consideration is given primarily to the subject of the contribution and secondarily to its presentation. All members and afiliates of PGMTT are eligible for the award. The award consists of a certificate, a monetary sum of $100, and a feature publication in these Transactions. If the paper has more than one author, the monetary sum is divided equally among the authors. View full abstract»

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  • General Treatment of Klystron Resonant Cavities

    Page(s): 344 - 358
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    Klystron resonant cavities are treated for general cases and their equivalent circuits are theoretically determined, which allows a fairly accurate estimate of resonant properties. It is shown that a reentrant cavity is expressed as a low-frequency series LCRse circuit or a shunt LCRsh circuit, taking L as the inductance of a toroidal coil with one turn and with a cross section the same as the cavity, C as the gap capacitance plus the equivalent capacitance of the cavity, and Rse or Rsh as the equivalent series or shunt resistance of the cavity at resonance. The introduction of the equivalent cavity capacitance has proved to be very effective. The formulas derived here enable one to calculate the resonant frequency within an error of a few per cent and the shunt resistance and the Q within an error of several tenths of a per cent in most cases, and thus should prove to be very useful to the designer of microwave circuits. View full abstract»

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  • A Unified Discussion of High-Q Waveguide Filter Design Theory

    Page(s): 359 - 368
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    For the general design of conventional, high-Q, direct-coupled waveguide filters to be based on the frequency behavior of a classical ladder network prototype, it is necessary and sufficient that the reflecting elements of the filter be replaceable by admittance inverters and that the lengths of transmission line be replaceable by resonant elements. The error due to the latter assumption is of the order of twice the square of the percentage bandwidth measured in guide wavelengths, and the classical synthesis problem is a limiting case of a solvable transmission line problem. In this limit, an exact equivalence is established between the design of a direct-coupled filter and the design of a quarter-wave-coupled filter based on the same ladder network prototype. Design formulas for equal ripple and maximally flat performance are given for the VSWR's of the reflecting elements in terms of dimensionless quantities. Detailed comparison of previous formulas is made. View full abstract»

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  • An Analysis of a Broad-Band Coaxial Hybrid Ring

    Page(s): 369 - 373
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    This paper describes a broad-band coaxial hybrid ring which has excellent isolation and balance characteristics. The ring differs from the conventional hybrid in that the fourth arm has a series-type balun feed and is positioned so that a plane of symmetry exists through two of the arms. Isolation between these arms and balance between the output arms are theoretically independent of frequency. The admittance and VSWR of the input arms are computed by bisecting the ring about the plane of symmetry and employing standard Smith Chart techniques. Corresponding experimental data are included. A comparison is made with the conventional coaxial hybrid ring. View full abstract»

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  • Some Notes on the Optimum Design of Stepped Transmission-Line Transformers

    Page(s): 374 - 378
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    This paper describes an optimum design of monotonic stepped transmission-line transformers when the reflection coefficient and the bandwidth ratio are prescribed. For the analysis, discontinuity capacitances and reflection interactions are neglected and the validity of the conclusions is therefore restricted to small steps. The analysis is applicable to a multistep transmission line of which the quarter-wave transformer is a special case. In particular, it is shown that if the number of steps is increased from three to five a larger bandwidth may be obtained, but it is not possible to reduce the over-all length in this manner. For a given bandwidth, the shortest taper is always a stepped transmission line and never a continuous one. View full abstract»

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  • Microwave Semiconductor Switching Techniques

    Page(s): 378 - 383
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    This paper describes new microwave techniques employing the properties of N-type germanium diode switches. For applications requiring very high isolations, multiple switches are added in tandem. With proper spacing, they form antiresonant cavity circuits. In this case the isolations and insertion losses in db are directly additive. A switch is described which is normally ON and is pulsed OFF. Finally, details are given of a switch in a hybrid-tee configuration in which switching isolations of 50 db are obtained with an insertion loss of 0.7 db. View full abstract»

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  • Microwave Q Measurements in the Presence of Coupling Losses

    Page(s): 383 - 389
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    In the use of the impedance (Q-circle) method of measuring the cavity Q values, the presence of losses in the coupling network (between the cavity and the available external terminals) is usually neglected. If appreciable losses are present this simplification is not justitied, and its use can lead to significant errors. The losses in any coupling network can be described by means of an equivalent canonical circuit containing a series and a shunt resistor. The losses due to the series element are immediately apparent from the character of the impedance locus when plotted on a Smith Chart and can be corrected for an "apparent" Q value. However, unless the shunt loss can be determined by a separate calibration of the coupling network, the apparent Q value will be ambiguous because the shunt losses occurring in the coupling network are not distinguishable from those in the cavity proper. Methods for using the impedance data for determining the Q values are given on the assumption that the coupling network parameters cm be found. It is also pointed out that due to the presence of coupling losses the loaded and external Q values are no longer uniquely defined, but their meaning depends upon the application of interest. Formulas relating these to the coupling network parameters are given. View full abstract»

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  • The Excitation of a Dielectric Rod by a Cylindrical Waveguide

    Page(s): 389 - 393
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    This paper is a theoretical analysis of the excitation of the lowest circular symmetric TM surface wave along an infinite circular dielectric rod by a metallic cylindrical waveguide coaxial with the rod. The asymptotic expressions for all the fields are obtained by means of the Wiener-Hopf method. The expressions for the total average power transmitted to the surface wave, the total average power reflected, and the total power radiated, per unit incident power, are derived and computed for epsilon=2.49 for various radii of the dielectric rod. View full abstract»

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  • An Investigation of the Properties of Germanium Mixer Crystals at Low Temperatures

    Page(s): 393 - 398
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    Experimental determinations of the noise temperature ratio, IF resistance, and conversion loss of 1N263 germanium mixer diodes operated in an X-band receiver are presented as a function of mixer temperature for the range -196°C to 27°C. No improvement in receiver noise factor was obtained by cooling the mixer to -196°C; however an improvement of 0.3 to 0.6 db was observed by cooling to a temperature in the region -100°C to -50°C. The exact value of the improvement and the optimum temperature depends on the individual crystal, as well as on dc bias and local oscillator drive. View full abstract»

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  • The Multiple Branch Waveguide Coupler

    Page(s): 398 - 403
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    A multiple branch directional coupler is discussed for rectangular waveguide applications for series junctions. A design method is developed which is valid for any coupling ratio and any number of branch lines with perfect match and directivity. The frequency response of this type coupler is calculated with the aid of a digital computer. View full abstract»

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  • Coupled-Transmission-Line Directional Couplers

    Page(s): 403 - 410
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    Formulas are presented for the design of coupled-transmission-line directional couplers that are rigorous for any value of coupling. Two basic types are treated in detail; the simplest is one-quarter wavelength long at the center of its frequency band, while the other is three-quarter wavelength long. The quarter-wavelength type can be used over an octave of frequencies with approximately consistant coupling, while the three-quarter-wavelength type can be used equally well over more than two two octaves. For example, a -3-db coupler of the first type has a variation of +-0.3 db over a 2:1 band, while the second type has the same variation over a 4.5:1 band. Theoretically both types should have infinite directivity at all frequencies. The experimental results for models of these directional couplers have been found to conform very closely to the theoretical coupling functions, while the directivity, although usually good, is limited by discontinuity effects and constructional tolerances. View full abstract»

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  • Design of a Full Waveguide Bandwidth High-Power Isolator

    Page(s): 411 - 414
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    An analysis of the microwave fields in rectangular waveguide indicates that circular polarization of the H-vector components exists at two planes only and the location of these planes is frequency dependent. Also, an examination of Kittel's theory reveals that resonance in ferrites can be made to occur at different frequencies for a constant value of dc magnetic biasing field provided the ferrites are characterized by different values of saturation magnetization. These two effects have been used concurrently in the design of an X-band waveguide isolator for operation over a 45 per cent bandwidth, and at high power levels. The theory underlying the design of this isolator is presented. Included is a treatment of the parameters which affect the isolator design. Finally, an operative isolator is described and its experimental characteristics are reported. View full abstract»

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  • A Simple Artificial Anisotropic Dielectric Medium (Correction)

    Page(s): 414
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    Robert E. Collin, author of "A Simple Artificial Anisotropic Dielectric Medium", which appeared on pages 206-209 of the April, 1958 issue of these Transactions, wishes to make the following correction to his paper. View full abstract»

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  • Wide-Band Microwave Transmission Measuring System

    Page(s): 415 - 418
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    A relatively broad-band balanced microwave measurement system has been built using a traveling-wave tube amplifier which permits automatic phase and amplitude transmission measurements to be made simultaneously as a function of frequency over the frequency range 8.7 kmc-9.6 kmc. A phase accuracy of +-1 degree can be achieved for a change of attenuation in the unknown of 24 db. Loss measurements can be made with an accuracy of +-2 per cent. The bridge is built largely of commercially available components and can be easily duplicated. The basic technique is compatible with additional broad-banding efforts as improved components become available, and it will eventually be applicable to all microwave frequencies. View full abstract»

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  • Method for Measuring the Directivity of Directional Couplers

    Page(s): 419 - 422
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    This method of measuring directivity requires the measurement of the ratio of powers delivered to the side arm when the normal input arm is connected alternately to an adjustable sliding termination and a sliding short circuit. The short circuit is phased to yield maximum and minimum responses and the amplitudes are averaged. Two techniques of adjusting the termination may be used, One procedure requires zero reflection from the termination. The other procedure requires adjustment for a null at the detector and then measurement of the maximum response due to changing the phase of the termination. The inherent errors of the method are analyzed and found to be within the limits--0.01 to 0.00 db in a specific example. View full abstract»

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  • Development of a High-Power L-Band Resonance Isolator

    Page(s): 423 - 428
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    Waveguide resonance absorption isolators have been developed for use under high peak and average power conditions at L band. Two ferrite materials, one a nickel aluminate ferrite, the other a nickel cobalt ferrite, were developed for this purpose. The characteristics of isolators using these two materials are described. View full abstract»

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  • High-Power Microwave Filters

    Page(s): 429 - 439
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    In order to obtain filters capable of handling very high power, the use of radial lines and uniform line discontinuities was investigated as the most promising approach. In this connection, it was necessary to consider the equivalent circuit and interaction for H-type radial line mated at each end to uniform TE10 waveguide for taper angles of 45°. It was found that the equivalent circuit was valid for taper angles of 45°, and that for engineering design purposes the interaction could be neglected. The author utilized the 45° tapers and the uniform lines to design a high-power microwave filter capable of handling 700 kw at 10 pounds pressure in 0.900 by 0.400 ID waveguide. The design procedure for a multielement filter is described utilizing a partly graphical approach. View full abstract»

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  • A Method of Calculating the Characteristic Impedance of a Strip Transmission Line to a Given Degree of Accuracy

    Page(s): 440 - 446
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    The calculation of the characteristic impedance of the strip transmission line TEM-mode can be reduced to the solution of a two-dimensional potential equation with the strip cross section determining the boundary conditions. Usually this potential equation is solved by conformal mapping, but only the most simple shapes permit exact mapping. Approximations may require considerable work and their accuracy is uncertain. This paper describes an alternative numerical method which is particularly suitable for boundaries consisting of any number of straight lines and right angles. It is based on relaxation methods, but by using also variational principles it derives an approximate value for the impedance, and an upper and lower bound with a difference as small as desirable. View full abstract»

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  • Ferrite Line Width Measurements in a Cross-Guide Coupler

    Page(s): 446 - 450
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    Theoretical and experimental results are presented to show that the line width and the g factor of a spherical ferrite sample can be measured in a cross-guide coupler. The method is much easier to instrument than the usual cavity method and the measurements are much easier to perform. Experimental verification with a cavity perturbation system indicates that the measured quantities are sufficiently accurate for most purposes. View full abstract»

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  • Applications of Directional Filters for Multiplexing Systems

    Page(s): 450 - 453
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    The design of microwave multiplexing systems for frequency channelization of a broad-band microwave spectrum is complicated by problems such as off-resonance mismatch and mutual interaction between adjacent filters. By employing directional filters as basic building blocks, it is possible to construct multiplexing filters with a perfect input match since the input VSWR of a directional filter is theoretically unity both at resonance and off-resonance. Less insertion loss of a manifold may be obtained by the use of directional filters than with conventional band-pass filters. Curves giving the predicted response of a manifold containing n elements are presented for single-tuned and double-tuned directional filters. An asymmetrical response shape is obtained which has a midband insertion loss related to the separation of adjacent channels. An experimental model consisting of a five-channel multiplexer has been constructed utilizing double-tuned-circular-waveguide directional filters. 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