The proliferation of mobile communications technology increases the demands for faster and more robust services, in addition to the ever decreasing sizes of antennas. These demands can be satisfied using circularly polarized (CP) dielectric resonator antennas (DRAs) exhibiting wide operational bandwidth capability. By utilizing such antennas, the probability of linking the transmitted and received signals is higher, and the system is more reliable since the CP wave is transmitted in all planes and less susceptible to unwanted reflections and absorptions. As CP system is insensitive to the transmitter and receiver orientation, the time consuming practice of continuously aligning the antennas can be avoided. Furthermore, the antennas profile can be reduced simply by using dielectric material with higher permittivity. The thesis focuses on the design and analysis of singly-fed regular-shaped DRAs with a wideband circular polarization. Two new single-point excitation schemes that can be easily used to excite an arbitrarily shaped DRA are introduced, where a square spiral and a rectangular open half-loop are used for DRA excitation. These proposed feeding methods are based on employing conformal conducting metal strips that are placed on the DRA surface. Additionally, two different approaches are employed onto the DRA design to enhance the CP bandwidth. The first approach is based on using a multilayer dielectric, and the second introduces a parasitic half-loop inside the feeding element. The generated broad CP bands have been achieved in conjunction with sufficient impedance matching bandwidths. The studied geometries have been modeled using a comprehensive self developed MoM code that employs the volume surface integral equation (VSIE). The computed results have been validated against those obtained from measurements as well as CST microwave studio simulations. Theoretical and experimental results demonstrate a several folds enhancement in the CP bandwidths compared to those reported in the literature for identical DRA geometries.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:578033 |
| Date | January 2012 |
| Creators | Sulaiman, Mohamad Ismail |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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