A 22.2 GHz Antenna for water vapour radiometry

[摘要] ENGLISH ABSTRACT: For this thesis a low-cost antenna solution for a low-cost water vapour radiometrysystem is designed. The most important specifications for the antenna isthat it has to have a -20 dB sidelobe level, a 3° -3 dB beamwidth and have tobe electronically steerable. It also has to be low-cost.The first design that is considered is the phased array solution as it can beelectronically steered. Since components can be etched onto the design themanufacturing cost is also reduced. The number of elements required for thisdesign to reach the specifications is determined to be more than 16x16 elements,and thus proves to be cost impractical. The analysis is tested bydesigning a 1x4 and 2x2 multilayered aperture coupled patch antenna arraywith a corporate feed network, to both test if a better antenna element designcan improve the results, and if the analysis is accurate in determining theimpracticality of an array design. This also proves that the array design isinfeasible.A reflector solution is then considered. The reflector system is designed tostatically observe in a few specified directions, removing the need for electronicsteering. Two parabolic reflectors and a conical horn is designed. Thereflectors are combined through interpolation into one larger reflector. Afterthe horn design proves to be ineffective, a new horn is considered that almostallows the reflector system to meet the specifications.Finally the system is measured, but unfortunately the measured result provesthat the physical system does not meet all the specifications. The sidelobelevel is around -16 dB, however, the -3 dB beamwidth is well below 3°.

[发布机构] Stellenbosch University