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Microwave Theory and Techniques, IRE Transactions on

Issue 5 • Date September 1962

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Displaying Results 1 - 25 of 29
  • [Front cover - Sep. 1962]

    Page(s): f1 - f2
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    Freely Available from IEEE
  • Table of contents - September 1962

    Page(s): 301
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    Freely Available from IEEE
  • Broad-Band TEM Diode Limiting

    Page(s): 302 - 310
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    The bandwidths of two types of limiters operating below diode resonance and one type of limiter operating at diode resonance are calculated. A 2.5-Gc base-band limiter was made providing a low power insertion loss of less than 1 db, a limiting threshold of 10 mw, and a high power isolation of greater than 20 db. A 0.9-to 1.3-Gc matched limiter was made having a VSWR of less than 1.2 for all power levels. The burnout power of these two limiters was calculated to be about 10 watts incident CW power or 1500 watt-microsecond incident pulse energy. Using the diode resonance the calculations indicate that it is possible to make a 5-Gc limiter with 15 per cent bandwidth, less than 1-db low power insertion loss, a limiting level of 10 mw, and greater than 20-db isolation at high power. The bandwidths derived for diode limiting are equally applicable to switching. View full abstract»

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  • Improvements in Light Modulators of the Traveling-Wave Type

    Page(s): 311 - 313
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    Wide-band modulation of light by means of the electro-optic effect requires a traveling-wave type of interaction, with the modulation field traveling with the same phase velocity as the light in some suitably proportioned structure. If electro-optic material is lossy at the modulation frequencies, the modulating field is strongly attenuated with a resultant low-modulation efficiency. A scheme is analyzed here in which power is continuously fed into the light-carrying guide to make up for the attenuation as the wave progresses down the guide. By suitably tapering the coupling and the uncoupled propagation constant, the electric field can be maintained constant in the light-carrying guide and the "coupled" propagation constant in this guide can be maintained in synchronism with the light wave, thereby increasing the modulation efficiency. View full abstract»

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  • Electromagnetic Waves in Waveguides with Wall Impedance

    Page(s): 314 - 320
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    A variational expression for the propagation constant of the waves in waveguides with inhomogeneous media and with wall impedance is presented. Using this expression, the shift of the propagation constant due to the wall impedance is calculated. It is also clarified how the removal of degeneracy takes place. Then the same problem is discussed using another approach, a perturbation method. The result is identical with that of the variational principle, as is to be expected. In the final section, taking degenerate TEM modes as an example, it is shown that appropriate choices of field configuration are necessary when the formula for an attenuation constant derived from the conservation of energy is applied to degenerate modes. View full abstract»

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  • A Three-Cavity Circularly Polarized Waveguide Directional Filter Yielding a Maximally Flat Response

    Page(s): 321 - 328
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    A directional filter is a completely matched four-port device which exhibits directional properties and a filter-like frequency characteristic. This paper extends work previously done on a single-cavity narrow-band circularly polarized waveguide directional filter to the case of three cavities connected in cascade with an overall bandwidth greater than 1 per cent. Analysis of the filter leads to a relationship between the two inner coupling factors and the two outermost coupling factors for a maximally flat response. The results obtained from an experimental filter using the design approach discussed herein compare favorably with the theoretical filter response. Directivity and band-elimination filter characteristics are discussed. View full abstract»

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  • Power Transmission Through General Uniform Waveguides

    Page(s): 328 - 331
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    The problem of transmitting electromagnetic power through a dissipative waveguide in an optimal fashion is examined. At any frequency the problem is reduced to a weighted eigenvalue problem in which the maximum efficiency appears as the eigenvalue and the required excitation is specified by the corresponding eigenvector. Numerical results are presented. View full abstract»

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  • Further Considerations on Fabry-Perot Type Resonators

    Page(s): 331 - 339
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    An integral equation valid for fabry-perot type resonators with reflectors of arbitrary curvature and spacing is derived, and equations for the planar, confocal, and spherical geometries are considered further. A numerical iteration method is used to solve the equations, and the properties of the various solutions for the different kernels are discussed. Results show that the confocal type has the lowest diffraction loss, and that the losses in the planar- and spherical-type geometries are identical, as are the normal mode field distributions over the reflectors, apart from a change in sign of the phase angle. Variational methods are applied to give results for the eigenvalues of the planar geometry with great facility, particularly for cases where the eigenvalues are closely spaced. Some potential uses and the respective merits of the resonators are briefly mentioned. View full abstract»

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  • Stepped-Impedance Transformers and Filter Prototypes

    Page(s): 339 - 359
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    Quarter-wave transformers are widely used to obtain an impedance match within a specified tolerance between two lines of different characteristic impedances over a specified frequency band. This paper gives design formulas and extensive tables of designs, most of which were especially derived so that an integrated account could be presented for the first time. Numerous examples are given. Only homogeneous, synchronous transformers and filters are included in this paper, but a short bibliography on related topics is appended. The theory is also applied to band-pass filters, by showing how to convert quarter-wave transformers into half-wave filter prototypes. The theoretical and numerical results presented are applicable to the design of impedance transformers, direct-coupled cavity filters, short-line low-pass filters, optical antireflection coatings and interference filters, acoustical transformers, branch-guide directional couplers, TEM-mode coupled-transmission-line directional couplers, and other circuits. These applications have been or will be dealt with in separate papers; this paper gives the basic theory and some of the numerical data required for these applications. View full abstract»

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  • In-Line Waveguide Calorimeter For High-Power Measurement

    Page(s): 359 - 366
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    The static in-line calorimeter measures the temperature rise in the walls of a waveguide caused by the attenuation of microwave power flowing through the waveguide. It is simple and inexpensive and can be constructed so that it will fit on waveguide already existing in a microwave system. The device should be reliable because it uses no active circuitry. In addition, few mechanical problems are encountered in its use because the existing waveguide need not be altered. The theory of the device is developed, and two experimental S-band calorimeters using stainless steel waveguide and resistance-wire bridge temperature indicators are described. The measured sensitivity and time constant for both units fall within the experimental error of confirming the theoretically predicted figures. View full abstract»

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  • Scattering of Surface Waves by Discontinuities on a Unidirectionally Conducting Screen

    Page(s): 367 - 375
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    It is shown that a plane screen consisting of closely-spaced parallel wires which are separated from one another and which are such that the radius of the wires and the spacing between them are small in comparison to wavelength, can support a surface wave, the spread of whose field components depends only on the angle which the direction of propagation makes with the direction of the wires. The problem of radiation from a discontinuity in such a semi-infinite waveguide is studied for the following three types of discontinuities: 1) when the waveguide terminates in empty space, 2) when it terminates at another such semi-infinite waveguide having different propagation characteristics, and 3) when it terminates at a perfectly conducting half-plane. In each case, the power reflection coefficient, where applicable the power transmission coefficient, the loss of power due to radiation, and its angular distribution are evaluated. The motivation for this investigation is briefly indicated. View full abstract»

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  • Surface Waves on Radially Inhomogeneous Cylinders

    Page(s): 375 - 382
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    A characteristic equation and a cutoff equation are derived for higher order surface-wave modes on lossless isotropic cylinders with arbitrary radial permittivity variation. The derivation, based on the use of the fundamental matrix of a set of differential equations, reduces analytical work and results in expressions well suited for digital computer evaluation of surface-wave eigenvalues and mode spectra. The theory is applied in an investigation of HE21 and EH/sub21/ mode propagation for a particular set of models for the radially varying permittivity. Typical results showing eigenvalue variation, dispersion characteristics and radial field variation, including experimental verification of dispersion characteristics, are shown. The method of analysis can be extended to anisotropic cylinders with permittivity a function of both radius and frequency. View full abstract»

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  • A Plasma Controlled Directional Coupler

    Page(s): 383 - 389
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    A new type of waveguide directional coupler is described which has a discharge tube as the coupling element in the common narrow wall between the guides. The use of the discharge tube allows continuous control of the amount of coupling between the guides. The theory of the coupler is given with curves for designing such a coupler. The paper describes the results obtained from a 3-db coupler. Measurements were made at a frequency of 450 Mc, of VSWR, noise output, and switching speed. These show a VSWR of the order of 1.3 over the control range, and an excess noise temperature with a peak of 20,000°K at one value of control current. The coupler is capable of switching up to speeds of 1000 cps. View full abstract»

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  • Couplings in Direct-Coupled Waveguide Band-Pass Filters (Correspondence)

    Page(s): 389 - 390
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    Couplings in direct-coupled waveguide band-pass filters can be described in two different ways. Cohn describes couplings in terms of normalized susceptances of the coupling circuit elements (e. g., posts or irises ). Dishal describes interstage couplings in terms of a coefficient of coupling between adjacent resonators. Although Cohn has briefly mentioned coefficients of coupling in his paper, the interchangeability of the two methods of describing the couplings has not been clearly established. View full abstract»

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  • Contraphaseshifter (Correspondence)

    Page(s): 390 - 391
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    A novel combination of ring hybrid and variable power divider is shown to result in a three-terminal device having a single matched input and two outputs whose relative phase can be continuously varied independent of their amplitude. View full abstract»

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  • A Beam Plasma Surface Wave Interaction (Correspondence)

    Page(s): 391 - 392
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    This communication describes the interaction of an electron beam with a beam-generated hydrogen plasma. As a result of this interaction the dc energy of the electron beam is converted into microwave energy in the plasma. View full abstract»

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  • A Double-Prism Attenuator For Millimeter Waves (Correspondence)

    Page(s): 392 - 393
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    A double-prism attenuator, similar to the one built by Garnham for use at 35 Gc, was built in the laboratory for use at 100 Gc and above. This attenuator utilizes the well-known fact that a wave which is incident on the interface between two dielectrics at an angle greater than the critical angle is totally reflected. If the wave is in a medium of index of refraction n and the other medium is free space the critical angle is θc = sin-1 1/n. View full abstract»

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  • Application of Sampling Theorem to the Synthesis of Transmission Line Tapers and Antenna Radiation Patterns (Correspondence)

    Page(s): 393 - 394
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    In this note it is demonstrated how the sampling theorem may be used to reduce the problems of transmission line taper synthesis and antenna aperture field synthesis to that of optimizing a polynomial. In both cases the problem may be stated mathematically in the following form: find the function g(x) which is zero outside the domain - π≤x≤π that will yield a desired f(u) where f(u) is given by the fourier transform of g(x). View full abstract»

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  • A Proposed Lossless Electronic Phase Shifter (Correspondence)

    Page(s): 394
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    Modern antenna array designs frequently require the use of high-speed, electronically controlled phase shifters. The use of low-noise receivers now becoming available also dictates the requirement that such phase shifters have zero, or very small, losses. The use of parametric devices as active elements in such phase shifters is particularly attractive because of their high degree of reliability, high frequency capability, and excellent noise performance. This memorandum proposes such an active electronic phase shifter, which accomplishes the additional function of providing amplification or attenuation independently of its phase shift. View full abstract»

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  • Oversize Waveguide Directional Coupler (Correspondence)

    Page(s): 394 - 395
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    Oversize rectangular waveguide using TE10 mode propagation has been suggested as a means of reducing the attenuation and fabrication difficulties of transmission lines and components for frequencies above 40 Gc. Experiments on straight sections of such transmission lines show that it is superior to pure optical transmission for short distances. View full abstract»

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  • Resonances in a Cylindrical Plasma Column (Correspondence)

    Page(s): 395 - 396
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    A plasma column irradiated by an electromagnetic wave which has its electric vector and direction of propagation perpendicular to the axis of the tube exhibits Tonks-Dattner resonances in its absorption pattern when the electron density in the column is varied. The pattern consists of a main resonance and a number of less pronounced subsidiary resonances at currents corresponding to electron densities lower than that of the main peak. The subsidiary resonances grow progressively smaller as the electron density decreases. View full abstract»

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  • Proposed Experiment for Eliciting Multiple Resonances from the Ionosphere (Correspondence)

    Page(s): 396 - 397
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    In the theory of Herlofson only one resonance is predicted for a cylindrical plasma column irradiated by an electromagnetic wave having both its direction of propagation and electric field E perpendicular to the axis of the column, a mode which he designates as sagittal. Herlofson treats the problem by solving the wave equation in cylindrical coordinates and then imposing boundary conditions to find the frequency or frequencies for maximum scattering from the column. In his treatment, the modes which involve Bessel functions of order higher than unity have the same resonant frequency as that for the dipolar mode for which the order of the Bessel function is unity. No resonances at all are predicted for the parallel mode of excitation in which E is parallel to the axis of the column. These predictions are contrary to the experimental observations of Dattner and others for the saggital mode and also contrary to the observations reported by Willis and Petroff in which a spectrum of resonances is found for the parallel mode. Experiments by Boley have shown that the sagittal scattering for the higher order resonances is that appropriate for a dipole, that is, his experiments show that the field about the column for the higher-order modes is not quadropolar or sextupolar. View full abstract»

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  • Stability Criteria for Tunnel-Diode Amplifiers (Correspondence)

    Page(s): 397 - 398
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    A tunnel-diode amplifier is stable when the amplifier network is reduced to an arbitrary single loop and the equation given by the sum of the impedances around this loop equal to zero [ΣZ(P)=0 where p= γ +jω ] has no solution in the right-half plane (γ>0). This is equivalent to the requirement that the system determinant shall have no zeros in the right-half plane. Several authors have used this criterion. To determine analytically whether ΣZ(p) has any positive zeros is very laborious if at all possible for many practical amplifier configurations. View full abstract»

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  • On "An Impedance Transformation Method for Finding The Load Impedance of a Two-Port Network" (Correspondence)

    Page(s): 398 - 399
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    The above article begins with ten extensive footnotes, but the authors omit the one reference that discusses their problem: Deschamps' "Hyperbolic Protractor." The undersigned writers concede that the method of Mittra and King is different, but it is more complicated and less useful than that of Deschamps. View full abstract»

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  • On "A Solid-State Microwave Source from Reactance-Diode Harmonic Generators" (Correspondence)

    Page(s): 399 - 401
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    In a recent paper, Hyltin and Kotzebue have given some interesting formulas about the maximum efficiency of reactance-diode harmonic generators. It may be interesting to submit to the attention of the authors some considerations about their theoretical analysis. 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