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With the increasing demand for high performance communication networks and the proliferation of mobile devices, significant advances in antenna design are essential. In recent years the rising demands of the mobile wireless communication industry have forced antennas to have increased performance while being limited to an ever decreasing footprint. Such design constraints have forced antenna designers to consider frequency agile antennas so that their behavior can adapt with changing system requirements or environmental conditions. Frequency agile antennas used for mobile handset applications must also be inexpensive, robust, and make use of electronic switching with reasonable DC power consumption. Previous works have addressed a number of these requirements but relatively little work has been performed on frequency agile dielectric resonator antennas (DRAs). The objective of this thesis is to investigate the use of DRAs for frequency reconfigurability. DRAs are an attractive option due to their compactness, very low losses leading to high radiation efficiencies (better than 95%) and fairly wide bandwidths compared to alternatives. DRA’s are also well suited for mobile communications since they can be placed on a ground plane and are by nature low gain antennas whose radiation patterns typically resemble those of short electric or magnetic dipoles. One way to electronically reconfigure a DRA, in the sense of altering the frequency band over which the input reflection coefficient of the antenna is below some threshold, is to partially load one face of the DRA with a conducting surface. By altering the way in which this surface connects to the groundplane on which the DRA is mounted, the DRA can be reconfigured due to changes in its mode structure. This connection was first made using several conducting tabs which resulted in a tuning range of 69% while having poor cross polarization performance. In order to address the poor cross polarization performance a second conducting surface was placed on the opposing DRA wall. This technique significantly reduced the cross polarization levels while obtaining a tuning range of 83%. The dual-wall conductively loaded DRA was then extended to include a full electronic implementation using PIN diodes and varactor diodes in order to achieve discrete and continuous tuning respectively. The two techniques both achieved discrete tuning ranges of 95% while the varactor implementation also had a continuous tuning range of 59% while both maintaining an acceptable cross polarization level.

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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2005. / Rogers, Peter, Committee Chair ; Ginsberg, Jerry, Committee Member ; Trivett, David, Committee Member. Includes bibliographical references.

Thesis (M.S. in Engineering Science (Electrical Engineering))--Naval Postgraduate School, Dec. 2004. / Thesis Advisor(s): Murali Tummala, Roberto Cristi. Includes bibliographical references (p. 79-81). Also available online.