Browsing by Author "Marais, Sarel Jacobus"

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    The quadrifilar helix antenna and its application to wide angle phase-steered arrays
    (Stellenbosch : Stellenbosch University, 2007-03) Marais, Sarel Jacobus; Palmer, K. D.; Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology.
    ENGLISH ABSTRACT: The quadrifilar helix antenna has frequently been employed to provide the wide angle, circularly polarized radiation pattern which is preferable for mobile satellite communications. A detailed study of this antenna and its varieties is presented. When used as an element in wide angle scanning arrays for aeronautical satellite tracking applications, the additional requirement of a low profile with light weight applies. This further complicates the realization of good circular polarization close to the horizon. A top disk is incorporated into various antenna structures in an effort to improve the radiation performance when used within a closely spaced array while reducing the height of the radiating element. The array performance of these elements are investigated which hints at a supported traveling mode aiding the ability to accomplish the wide angle beam steering. Subsequent study of leakywave antennas initiated the study and implementation of leaky-wave structures in phased arrays of quadrifilar helix elements.