| The navigation terminal devices develop toward bandwidth broadening,miniaturization and low cost,as result of the improvement of global satellite navigation systems,especially the fast progress of Chinese BeiDou Navigation Satellite System.In order to meet the requirement of the terminal devices,it becomes especially important for the terminal antenna to possess the above characteristics.The thesis mainly focuses on the analysis,simulation and test of miniaturized circularly polarized antenna with bandwidth broadening.Finally two circularly polarized antennas based on the reactive impedance surface(RIS)are designed and fabricated.The major contributions of the thesis are summarized as follows.After the analysis on the status of satellite navigation system,a study about microstrip antenna is carried out on basic parameter and circular polarization principle.Then the microstrip antenna miniaturization technology is analyzed in detail and the theory of split-ring resonator(SRR)and RIS is introduced.A slotted GPS terminal antenna fed by a single port is researched and designed.The antenna consists of dual-layer structure.The right-handed circular polarization is excited by an asymmetrical U-shaped slot loaded on the radiation patch,and the RIS structure is applied to achieve miniaturization and good gain performance.A miniaturized circularly polarized antenna with bandwidth broadening is researched and designed.The antenna is fed by single coaxial probe.The right-handed circularly polarized radiation is achieved by an asymmetric cross slot cut along the orthogonal directions in the center of patch,and the modified RIS with a balanced slot can miniaturize the antenna size.Meanwhile,the impedance bandwidth and axial ratio bandwidth of the antenna are increased by loading four sequentially rotated SRRs around the radiation patch.Measured results show that the proposed antenna has 10-dB impedance bandwidth of 8.0%(2.42—2.62 GHz)and 3dB axial ratio bandwidth of 3.2%(2.45—2.53 GHz). |
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