The Use Of Improved Ground Plane On The Anti-Multipath Antennas With Phase Center Stability

The soaring development of the satellite navigation technology nowadays requires better performance of the antennas on the terminal end. And to what extent of measurement accuracy the navigation satellite receiver can obtain is influenced by the measurement antennas, which play a critical part in the navigation satellite receiver. The phase center variation of antenna and the multipath effect are two main sources of measurement error in the highly accurate satellite navigation system. Thus anti-multipath effect and phase center stability are always emphasized throughout the design of high accuracy measurement antennas. The aim of this thesis is to compare and discuss the effect of different ground plane structure on the radiation characteristics of the circularly polarized microstrip antenna and the planar spiral antenna, both of which are the common forms of navigation satellite receiving antennas. The main work of this thesis includes:1. This thesis analyses the effect of the far field calculation boundary on the result of the antenna phase pattern. And the model of half wavelength dipole and circularly polarized microstrip antenna is exemplified to compare the different phase pattern result obtained from CST Microwave Studio and Ansys HFSS with respect to different simulation settings.2. This thesis proposes the simulation model of both a linearly and polarized microstrip antenna loaded with split ring resonators(SRR) with improved forms. This part of work includes the analysis of near field at the antenna’s radiation backlobe and the discussion of the grid mesh of the SRR in the simulation software. The simulation model of the linearly polarized antenna loaded with SRR is simplified in structure and increased in its front-to-back ratio compared with the original model. The bandwidth of the performance improvement is enlarged as well. The simulation improved model of the circularly polarized antenna loaded with SRR is also simplified in shape compared with the original model and improved in the phase center stability.3. The far field of the circularly polarized microstrip antenna with its ground plane loaded with choke ring, microwave absorber and EBG is made comparison of respectively, and the comparison is also made of the planar spiral antenna loaded with a cavity with absorber filled in and with a EBG structure. The results show for the circularly microstrip antenna, the improved forms of ground mentioned above each has its advantage of improving the far field,while the narrow bandwidth of the EBG structure might limit its application in the braodband.