Research On Accurate Measurement Of Antenna Polarization Characteristics

Antenna plays a decisive role in modern wireless communications and it has become one of the research hotspots.The measurement technology of the antenna has also developed continuously.However,there is less quantitative research for the antenna polarization characteristics measurement technology.Thus,it is necessary to take a further study for accurate measurement about the antenna polarization characteristics.According to antenna polarization characteristics' theoretical and measurement method,this thesis mainly studies the influence of the imbalance feed on the antenna polarization characteristics.Besides,a dual-circular polarization and quadruple-ridged horn antenna is designed in this thesis by using the balanced feeding technology.Firstly,this thesis introduces the basic theory of antenna polarization characteristics,analyses the basic concept of electromagnetic wave polarization and different types of polarization,then describes concepts of the relevant polarization characteristics and the polarization loss caused by polarization mismatch.Furthermore,besides linearly polarized antennas,both polarization characteristic parameters measurement and uncertainty analysis of circularly polarized antennas are described through the antenna polarization characteristics measuring method which is widely used in international.For obtaining the measurement data and demonstrating the accuracy of the measurement in the extrapolated electromagnetic darkroom,a set of polarization characteristics measurement for linearly polarized antennas was taken with the measurement method mentioned above.The next part a double-fed circular polarization microstrip antenna is designed by using the electromagnetic simulation software CST based on related technologies of microstrip antenna design.It's worth noting that this part mainly focuses on the influence of the antenna on its polarization characteristics under the condition of unbalanced phase and amplitude of the feed,after analyzing the axial ratio,principal polarization component and orthogonal polarization component of the antenna.Overall,based on the influence of imbalance feed on antenna polarization characteristics,this thesis presents a dual-circular quadruple-ridged horn antenna model with the feed-balancing technology.In CST simulation software,the influence of changing one set of feeds' phase and amplitude on the antenna polarization characteristics was studied.By analyzing results,this antenna can eliminate the influence of imbalanced feeds to some extent and keep its own polarization characteristic parameters to be maintained within a certain range.The simulation results illustrate that the antenna has a high polarization purity.In addition,the feed-balancing design can eliminate the influence of imbalanced feeds to some certain extent.Therefore,this design proves that the antenna can be used as a standard polarized antenna and be used in antenna polarization measurement work,meanwhile the antenna can significantly improve the accuracy of antenna polarization measurement.