Browsing by Author "Dodson, Samuel Christopher Keightley"
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- ItemDesign and adaptation of a folded split ring resonator antenna for an animal borne sensor(Stellenbosch : Stellenbosch University, 2018-03) Dodson, Samuel Christopher Keightley; Wiid, P. G.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: This thesis describes the selection, design, adaptation and construction of a folded split ring resonator (FSRR) antenna to replace the existing transmitting antenna in an animal-borne behavioural monitoring system (ABBMS). The antenna is required to fit completely inside a small rectangular enclosure of dimension 105 x 65x 26 mm, which is attached to the rear leg of a rhinoceros. An FSRR antenna is selected from a group of candidate antennas based on its high radiation and re ection efficiencies erad and eref , quasi-isotropic radiation pattern, small electrical size and availability of impedance tuning mechanisms. A prototype model is designed and optimised in FEKO simulation software and is manufactured on FR-4 substrate. It is then compared to a similar FSRR design from the literature and is found to behave similarly, even though the substrate on which our prototype is constructed is more affordable. The prototype is then adapted to fit inside the enclosure. The prototype antenna is reduced from a 3-dimensional to a planar form to incorporate a small surface mount balun. The planar model is transformed from a circular shape to a rectangular shape, and a thicker FR-4 substrate is included. The length and breadth of the antenna are set to 103:5 mm and 63:5 mm respectively. These transformations reduce the eref and erad values. However, the model now fits inside the enclosure. The feed of the rectangular model is subsequently inverted to face inward, to allow the incorporation of sensor electronics onto the antenna's substrate in the future. This further decreases eref . The eref is increased by adjusting the inner-feed antenna's tuning parameters. The resulting model is constructed and compared to the first circular prototype. It is shown to operate with higher eref and it also maintains the quasi-isotropic radiation pattern. However, the thick FR-4 substrate decreases the erad. This decreases the realised gain below the requirement. It is recommended to use a low loss substrate, of a similar permittivity, to alleviate this.