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  • 1
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    Characterization of quasi-optical filters with picosecond transient radiation (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The broadband microwave transmission properties of quasi-optical components are characterized with optoelectronically generated, picosecond transient radiation. The polarization sensitivity of a lithographically fabricated wire grating, from 15-140 GHz, is presented. The complex transmission functions of two different uniform arrays of cross dipoles are measured and compared with theoretical predictions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation (ISSN 0018-926X); 40; 63-66
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  • 2
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    Interpolation solutions for the problem of synthesis of dual-shaped offset reflector antennas (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Synthesis of dual-shaped offset reflector antennas to control the exit aperture distribution of amplitude and phase has received considerable attention in recent years. For a given feed illumination and desired aperture field distribution, an exact formulation of the problem of simultaneously synthesizing the shapes of the sub and main reflectors was presented recently by Galindo-Israel et al. (1987) in terms of a set of nonlinear first-order differential equations. In this paper, a numerical approach to solving these equations is discussed which circumvents some of the difficulties encountered by Galindo-Israel et al., particularly for small values of theta.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Microwave and Optical Technology Letters (ISSN 0895-2477); 2; 43-47
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  • 3
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    Offset dual-shaped reflectors for dual chamber compact ranges (1991)
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    Publication Date: 2011-08-19
    Description: The application of the theory of the synthesis of offset dual-shaped reflectors to the design of compact ranges is examined. The object of the compact range is to provide a uniform plane wave with minimum amplitude and phase ripple over as large a volume as possible for a given size reflector. Ripple can be lowered by reducing the edge diffraction from the reflector producing the plane wave. This has been done either by serrating or rolling the edge. An alternative approach is to use dual offset-shaped reflector synthesis techniques to produce a reflector aperture distribution that is uniform over most of the aperture, but with a Gaussian taper near the edge. This approach can be used together with rolling and/or serration if desirable. The amount of phase and amplitude ripple obtained with two different dual-shaped reflector designs is studied as a function of position in the plane wave zone and reflector size in wavelengths. The amount of both transverse and longitudinal (z-component) cross polarization is studied.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation (ISSN 0018-926X); 39; 1007-101
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  • 4
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    On the theory of the synthesis of offset dual-shaped reflectors - Case examples (1991)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In an earlier paper by Galindo-Israel et al. (1987), the geometrical optics (GO) principles, constraints, and requirements of the dual- and single-offset-shaped reflector synthesis problem were collected and developed into a set of nonlinear first-order PDEs. An extension of the methods by which solutions to the PDEs can be obtained is presented, together with several case examples. These examples are independently analyzed by GO and physical optics diffraction methods. The starting point for the integration over each reflector can be taken on the outer rim, at the center, or at an intermediate point-the intermediate starting point being the more general case. The utility of the speed of this synthesis method is demonstrated. For example, the program utilized completes a synthesis in less than 45 s on a 386/20 personal computer and within a fraction of a second on a mainframe Cray. This makes practical the incorporation of the synthesis into a search algorithm that can optimize one or more parameters of the reflector system. As an example, the optimization of the mapping equations for low cross polarization is discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation (ISSN 0018-926X); 39; 620-626
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  • 5
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    Determination of a natural basis function set on thick, structured slabs using Prony's method (1991)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The calculation of currents on a thick, structured slab such as a thick slab of honeycomb is discussed. Unfortunately, for certain applications, the slab can be on the order of several wavelengths, so that the straightforward application of the method of moments using subdomain basis functions is too expensive. The authors discuss how to apply Prony's method to the currents calculated for a thin, structured slab to obtain a natural set of basis functions to represent the currents in the interior of a thick slab. Prony's method represents the currents as a series of complex exponential functions. The thick slab problem is then solved by the method of moments using subdomain basis functions near the slab interfaces and one or two of the complex exponentials as basis functions within the slab.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation (ISSN 0018-926X); 39; 1240-124
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  • 6
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    On the theory of the synthesis of single and dual offset shaped reflector antennas (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two reflectors shaped so as to transforn a geometrical optics (GO) feed power pattern into a uniform amplitude and phase aperture distribution are indicated schematically. Single- and dual-shaped geometrical optics problems are solved via exact solutions obtained by progressive integration. It is concluded that an infinite set of such solutions exists.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation (ISSN 0018-926X); AP-35; 887-896
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  • 7
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    Multi-system approach to speech understanding (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The Harpy and Hearsay-2 systems are described. The performance of these systems was tabulated. The large number of design decisions which confront a speech understanding system are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 11-23
    Format: application/pdf
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  • 8
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    APS-Workshop on Characterization of MMIC (Monolithic Microwave Integrated Circuit) Devices for Array Antenna (1987)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The IEEE AP-S ADCOM is attempting to expand its educational, tutorial and information exchange activities as a further benefit to all members. To this end, ADCOM will be forming specialized workshops on topics of interest to its members. The first such workshop on Characterization and Packaging of MMIC Devices for Array Antennas was conceived. The workshop took place on June 13, 1986 as part of the 1986 International Symposium sponsored by IEEE AP-S and URSI in Philadelphia, PA, June 9-13, 1986. The workshop was formed to foster the interchange of ideas among MMIC device users and to provide a forum to collect and focus information among engineers experienced and interested in the topic. After brief presentations by the panelists and comments from attendees on several subtopics, the group was divided into working committees. Each committee evaluated and made recommendations on one of the subtopics.
    Keywords: COMMUNICATIONS AND RADAR
    Type: AD-P005398 , Illinois Univ., Proceedings of the Antenna Applications Symposium held in Urbana, Illinois on 17-19 September 1986, Volume 1; p 119-133
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  • 9
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    Techniques for analyzing frequency selective surfaces - A review (1988)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: A number of representative techniques for analyzing frequency-selective surfaces (FSSs), which comprise periodic arrays of patches or apertures in a conducting screen and find important applications as filters in microwaves and optics, are discussed. The basic properties of the FSSs are reviewed and several different approaches to predicting their frequency-response characteristics are described. Some recent developments in the treatment of truncated, curved, and doubly periodic screens are mentioned and representative experimental results are included.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE, Proceedings (ISSN 0018-9219); 76; 1593-161
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  • 10
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    The use of the FFT for the efficient solution of the problem of electromagnetic scattering by a body of revolution (1990)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The enhancement of the computational efficiency of the body of revolution (BOR) scattering problem is discused with a view to making it practical for solving large-body problems. The problem of EM scattering by a perfectly conducting BOR is considered, although the methods can be extended to multilayered dielectric bodies as well. Typically, the generation of the elements of the moment method matrix consumes a major portion of the computational time. It is shown how this time can be significantly reduced by manipulating the expression for the matrix elements to permit efficient FFT computation. A technique for extracting the singularity of the Green function that appears within the integrands of the matrix diagonal is also presented, further enhancing the usefulness of the FFT. The computation time can thus be improved by at least an order of magnitude for large bodies in comparison to that for previous algorithms.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation (ISSN 0018-926X); 38; 313-322
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