Design and Measurement Methodologies of Low-Cost Smart Antennas.

This thesis presents a number of design methodologies and a cost-effective measurement methodology of low-cost, low-power consumption smart antennas for applications in wireless and satellite communications. To reduce cost, the Electronically Steerable Parasitic Array Radiator (ESPAR) antennas, which are low-cost solutions compared with traditional smart antennas, are employed. To reduce the antenna size, the methods, in which both the driven element and the parasitic elements can be made small, are developed. Then these small components are used to construct different compact smart antennas for different applications. The contributions to the design methodologies are focused on: (1) compactness (i.e. small size both on antenna height and radius whilst achieving reasonable directionality and beam-forming abilities); (2) high-gain (i.e. low-profile whilst still achieving higher antenna gain by using the novel designed small directors); (3) broad-bandwidth; (4) dual-band; (5) polarisation re- configurability; (7) antenna array (i.e. using Multiple-Input-Multiple-Output (MIMO) technologies to improve channel capacity); (8) adoption of electromagnetic band-gap (EBG) Metarnaterials realizing steerable beams; (9) integration into other antennas such as the Yagi-Uda antenna, circularly-polarised (Cl') antenna, and a reconfigurable reflectarray antenna. Furthermore, the application to Wireless Sensor Network (WSN) communications within a multipath environment is assessed where significant improvement over system throughput is demonstrated against commonly used omni-directional antennas. All the antenna designs are characterised numerically ar1d also, where possible, experimentally. The contributions to the measurement methodology are focused on developing cost-effective measurement approaches for direct smart antenna Signal-to-Interference Ratio (SIR) and radiation pattern characterisation prior to input to a transceiver. Several kinds of low-profile and low-cost ESP AR antennas have been designed, constructed and measured for the first time and specific advances are: Low-profile folded monopole ESPAR Low-profile Yagi-Uda antenna where, for the first time, the height of the Yagi-Uda antenna has been reduced by 50%. Low-profile folded monopole ESP AR with the small director array achieving higher antenna gain where, for the first time, the antenna height of the ESPAR antenna has been reduced from typically 0.25 ~ to 0.1 ~. ii