Thesis (MScIng)--University of Stellenbosch, 2007. / 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. / AFRIKAANSE OPSOMMING: Die vierledige heliksantenna word dikwels gebruik vir toepassings wat ’n wye,
sirkulêr gepolariseerde stralingspatroon benodig. ’n Verskeidenheid van hierdie
antennas is noukeurig bestudeer en hul toepaslikheid vir mobiele sattelietkommunikasie
ondersoek. Wanneer hierdie antennas in fase gestuurde skikkings gebruik
word, word dit ook vereis dat die eenhede liggewig is met ’n lae profiel. Dit bemoeilik
die verkryging van goeie sirkulêre polarisasie naby die horison aansienlik.
In ’n poging om die wyehoek straling met kort antennas te verbeter, is ’n
oorhoofse skyf tot verskillende heliksstrukture toegevoeg. In nou gespasieerde
skikkings maak hierdie skywe ’n positiewe bydrae to wyehoekstralingeienskappe.
Die invloed van lekmodusse wat binne die struktuur voortplant is ondersoek en
gebruik in skikkings waarvan die bundel naby aan die horison gestuur word.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21675 |
| Date | 03 1900 |
| Creators | Marais, Sarel Jacobus |
| Contributors | Palmer, K.D., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | xvi, 102 leaves : ill. |
| Rights | Stellenbosch University |
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