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Microwave Theory and Techniques, IEEE Transactions on

Issue 3 • Date Mar. 1971

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Displaying Results 1 - 20 of 20
  • [Front cover - March 1971]

    Page(s): f1 - f2
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  • Table of contents - March 1971

    Page(s): 259
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  • Design of a New Broad-Band Isolator

    Page(s): 260 - 269
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    The design theory and experimental results of a proposed broad-band technique of an isolator are presented. The isolator not only has a broad-band backward loss but also a low broad-band insertion loss. The network constants and the performance are obtained in connection with the magnetic loss of ferrite, and they are confirmed by experimental data. The trial ultrawide-band isolator the performance of 20-dB isolation over the frequency band from 70 MHz to 800 MHz. View full abstract»

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  • Variable Tunneling Excitation of Optical Surface Waves

    Page(s): 269 - 276
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    A method for coupling an optical beam into thin films utilizing shaped tunneling regions is described. It is shown that in principle all of the power can be coupled into the film. For ease of fabrication, a uniform gradient structure is preferable, however, and yields coupling of over 90 percent for incident coherent Gaussian beams. Experimental coupling values with gradient tunneling regions are in excess of 50 percent. Good mode isolation and elimination of prism edge effects are major features of the coupler. The experimental coupling values are obtained from a transmission measurement utilizing two prisms. View full abstract»

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  • Propagation Characteristics of Periodic Arrays of Dielectric Slabs

    Page(s): 276 - 286
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    Propagation along periodic arrays of dielectric slabs in the direction transverse to that of periodicity is studied as a function of the prescribed phase delay per period for two polarizations. Classification of modes is achieved with the help of "stability diagrams." In contrast with previous work, the rigorous dispersion relation and exact mode functions are considered. Calculated dispersion curves and closed form mode functions serve to illustrate the guiding properties of the structure and are, in turn, explained in terms of stability diagrams and equivalent networks. View full abstract»

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  • An Improved Interferometric Polarization Analyzer for Measuring the Microwave Magneto-Kerr Effect in Semiconductors

    Page(s): 287 - 294
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    An interferometric polarization analyzer for measuring the microwave magneto-Kerr effect in semiconductors is described and analyzed, and compared with earlier systems used for the same purpose. The system described utilizes a 4-port waveguide junction referred to as a dual-mode transducer (DMT). This system has important advantages over systems previously used to measure the microwave magneto-Kerr effect. Preliminary data taken with the system are presented and sources of error discussed. View full abstract»

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  • The Design of Evanescent Mode Waveguide Bandpass Filters for a Prescribed Insertion Loss Characteristic

    Page(s): 295 - 308
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    A design theory for evanescent dominant mode waveguide filters is presented. The cutoff guide is represented by its equivalent /spl pi/-section network, the elements of which closely approximate lumped inductances. Resonators may be formed by introducing appropriate capacitive obstacles at suitable intervals along the guide. The filter that results is a microwave analog of lumped inductance filters with series inductance coupling, the magnitude of the series "inductance" being controlled by the separation between capacitive obstacles. The theory derives the equivalent ladder network from the low-pass prototype and is accurate up to at least 20 percent band-widths. Filters may be designed to couple into other cutoff waveguide components using the same basic principles, a propagating guide, and coaxial terminations. The filters are normally constructed in standard production waveguide and are simple and cheap to manufacture. A considerable size and weight reduction, compared with orthodox waveguide filters, is possible at the cost of a small increase in insertion loss. View full abstract»

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  • Lumped Parameters of a Reentering Cylindrical Cavity

    Page(s): 309 - 314
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    The cylindrical reentering cavity is studied. It is shown how lumped equivalent parameters can be known that are one inductance and two capacitances. These elements can be measured experimentally. Thus the problem of coupling with an active solid-state element, defined itself by lumped equivalent parameters (inductances and capacitances), is accurately solved. View full abstract»

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  • Computer Analysis of E-Plane Resonance Isolators

    Page(s): 315 - 322
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    E-plane ferrite resonance isolators are commonly used in most medium-power waveguide systems, allowing to effectively decouple successive stages. The study of propagation in this type of structure leads to a set of transcendental equations, for which exact theoretical results have not been available so far. The design of these devices has been done experimentally, which is time consuming and does not allow for achievement of optimal performance due to the large number of parameters involved. The present study considers the TE/sub m0/, modes in an isolator structure. A matrix formalism is used to derive the dispersion relation, which is then solved with the help of a computer program. Experimental results for a simple structure show good agreement with the computed values. The influence of ferrite parameters on the isolation and forward losses is presented. Higher order modes in the structure and the methods to avoid them are discussed. Finally, the field distribution in the device is determined, showing a large concentration of the fields within the loading material. View full abstract»

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  • Computer Optimization of E-Plane Resonance Isolators

    Page(s): 322 - 331
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    A method has been developed to optimize the geometry of the structure and the permittivity of the dielectric material used in E-plane isolators, for an arbitrary ferrite material. The structure is first computer analyzed, using an exact analytical approach. The minimum isolation and the maximum forward attenuation per unit length are calculated within a specified frequency band. The objective function, defined as the ratio minimum isolation per maximum forward losses, is then maximized. Several optimization procedures are compared and tested; the optimum gradient method was found to be well suited to this problem. Various optimized results are presented. View full abstract»

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  • Analysis of a Microwave Resonator-Feedback Oscillator (Correspondence)

    Page(s): 331 - 332
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    The temperature stability of the oscillation frequency, (/spl Delta//spl omega/ / /spl omega/)/ /spl Delta/T, of an S-band feedback oscillator is derived in terms of the temperature stability of the stable resonator and that of the circuits external to the resonator. Conditions have been established for the optimum external circuit to achieve temperature stability of the oscillation frequency. View full abstract»

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  • Minimum Noise Figure of Paramps with F2 Frequency Dependent Apparent R/sub s/ (Correspondence)

    Page(s): 333 - 334
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    The effect of inverse-squared frequency dependence of the apparent resistance of varactor diodes is discussed in the optimization of the noise figure of negative resistance and up-converter parametric amplifiers. Optimum idler frequency for a given signal frequency for minimum noise figure is calculated. It is also shown that about twofold improvement in the noise figure is obtained if the proper idler frequency is used for negative resistance amplifiers. It is also shown that the value of the optimum loading changes for upconverter amplifiers. View full abstract»

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  • Electronically Variable Low-Dispersion YIG Delay Line (Correspondence)

    Page(s): 334 - 337
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    A low dispersion YIG line was reported by Kirchner, Olson, and Bennet for which the delay was mechanically variable. A low dispersion YIG line, for which the delay is electronically variable, is described. A brief analysis is presented which determines the required magnetic field gradient needed to achieve objective dispersion characteristics. Approaches toward achieving the required field gradient are described. The resulting dispersion, almost constant and less than one-third of the typical dispersion for larger delays, is compared in detail with typical YIG line dispersion characteristics. View full abstract»

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  • A Simple Tuning Circuit for Waveguide and Transmission Line Systems (Correspondence)

    Page(s): 337 - 338
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    A simple tuning circuit for source or load matching is described that makes possible smooth and sensitive adjustments with no "holes" in frequency coverage over a complete waveguide band. Energy is coupled out of the mainline, the phase and magnitude adjusted with phase shifter and attenuator and fed back into the mainline to cancel the reflected signal. A simple analysis of the circuit is presented, and a graph given for estimating the maximum voltage standing-wave (VSWR) that can be "tuned out." Application to measurement of reflection coefficient or to impedance is proposed. View full abstract»

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  • Comments on "Use of Symmetry in the Variational Treatment of a Magnetoplasma-Filled Waveguide" [Correspondence]

    Page(s): 338 - 339
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    The "variational" formula established by Champlin is replaced in a general formulation of linear equations and adjoint equations. It is shown not to be stationary about the true guided fields. View full abstract»

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  • Noise Temperature Data on Cataphoretically Pumped F13T5 Lamps (Correspondence)

    Page(s): 339 - 341
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    Hg was removed from most of the positive column of an F13T5 lamp by cataphoresis; the Hg was trapped in the cathode region by cooling the bulb with ice. Noise temperatures were measured in the region of the lamp in which only an Ar discharge at 4.5 mmHg was taking place. The excess noise of the Ar discharge is given as a function of the dc discharge current from 60 to 2510 mA. An excessively large amount of noise that increased with discharge current was found to exist in the Hg portion of the discharge in the cathode region of some of the lamps. In some cases, this noise was coupled into the Ar discharge region and caused an apparent increase in the Ar noise temperature. View full abstract»

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  • Information on computer program descriptions

    Page(s): 345
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  • Information for authors

    Page(s): 346
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  • [Back cover]

    Page(s): b1 - b2
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Aims & Scope

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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