Research Of Dielectric Resonator Antennas For Satellite Navigation And Frequency-Reconfigurable Applications

With the rapid development of satellite navigation service, urgent demands have been asked for antennas that operating with circular polarization, high efficiency and low loss, as antennas are crucial components between satellites and terminals. Frequency-reconfigurable antennas can not only work at given frequencies, they can also choose to work at idle channels automatically, which provides a solution for easing channel congestion and improving spectrum utilization efficiency. Considering the many advantages such as compact size, ease of excitation, wide bandwidth, high efficiency, and low loss, dielectric resonator antennas(DRA) are promising in satellite navigation and mobile communications. In this thesis, DRAs for satellite navigation and frequency-reconfigurable applications are studied, and concrete work is as follows:Firstly, single feed circularly polarized DRAs are studied. Changes of the parameters for generating circular polarization such as operating mode, ceramic sizes, and feeding method are investigated. Based on the compass satellite navigation applications, single band and dual band circularly polarized DRAs are studied. For optimizing the impedance match of the dual band circularly polarized DRA, a cross slot is introduced to feed DRA.Secondly, a frequency-reconfigurable DRA is studied. Changes of the parameters for frequency tuning such as cavity sizes, current distribution, and equivalent electrical volume are investigated. Based on modern communications, a frequency-reconfigurable DRA which can operate over a wide band range is studied. For obtaining frequency reconfigurability, a variable-depth cavity is introduced. The variable-depth cavity is controlled by a system consists of a stepping motor and a single chip microcomputer.