A 22.2 GHz Antenna for water vapour radiometry

Cerfonteyn, William (2019-04)

Thesis (MEng)--Stellenbosch University, 2019.


ENGLISH ABSTRACT: For this thesis a low-cost antenna solution for a low-cost water vapour radiometry system is designed. The most important specifications for the antenna is that it has to have a -20 dB sidelobe level, a 3° -3 dB beamwidth and have to be electronically steerable. It also has to be low-cost. The first design that is considered is the phased array solution as it can be electronically steered. Since components can be etched onto the design the manufacturing cost is also reduced. The number of elements required for this design to reach the specifications is determined to be more than 16x16 elements, and thus proves to be cost impractical. The analysis is tested by designing a 1x4 and 2x2 multilayered aperture coupled patch antenna array with a corporate feed network, to both test if a better antenna element design can improve the results, and if the analysis is accurate in determining the impracticality of an array design. This also proves that the array design is infeasible. A reflector solution is then considered. The reflector system is designed to statically observe in a few specified directions, removing the need for electronic steering. Two parabolic reflectors and a conical horn is designed. The reflectors are combined through interpolation into one larger reflector. After the horn design proves to be ineffective, a new horn is considered that almost allows the reflector system to meet the specifications. Finally the system is measured, but unfortunately the measured result proves that the physical system does not meet all the specifications. The sidelobe level is around -16 dB, however, the -3 dB beamwidth is well below 3°.

AFRIKAANSE OPSOMMING: Vir hierdie tesis is ’n lae koste antenna oplossing vir ’n lae koste water damp radiometrie stelsel ontwerp. Die belangrikste spesifikasies v ir d ie a ntenna is dat dit ’n -20 dB sylob vlak het, ’n 3° -3 dB bundelwydte het en elektronies stuurbaar is. Dit moet ook ’n lae koste ontwerp wees. Die eerste ontwerp wat oorweeg word is die fase stuur samestelling oplossing omdat dit elektronies gestuur kan word. Aangesien die komponente ingeëts kan word in die ontwerp, word die vervaardigings koste ook verminder. Die hoeveelheid elemente wat benodig word vir hierdie ontwerp om die spesifikasies te bereik word bepaal om meer as 16x16 elemente te wees, en dus bewys dit om koste oneffektief te wees. Die analiese is getoets deur die ontwerping van ’n 1x4 en 2x2 multilaag opening gekoppelde mikrostrook antenna samestelling met ’n corporatiewe voer netwerk, om beide te toets of ’n beter antenna element ontwerp die resultate kan verbeter en of die analiese akkuraat is in die bepaling van hoe onprakties die antenna ontwerp is. Hierdie bewys ook dat die antenna ontwerp koste oneffektief is. ’n Reflektor o plossing i s d an o orweeg. D ie r eflektor si steem is on twerp om staties in ’n paar spesifieke rigtings te observeer, wat die behoefte vir elektroniese stuurbaarheid verwyder. Twee paraboliese reflektors en ’n koniese horing antenna is ontwerp. Die reflektors i s g ekombineered d eur i nterpolasie i n een groter reflektor. Na d ie h oring o ntwerp b ewys word om o neffektief t e wees, word ’n nuwe horing oorweeg wat amper die reflektor s isteem t oelaat om die spesifikasies te bereik.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/105808
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