Research And Design Of Beidou Dual-frequency Circularly Polarized Antennas And Arrays

In recent years,with the rapid development of wireless communication technologies and the gradual improvement of the construction of global navigation and positioning systems,satellite navigation systems have played an important role in the military and civilian fields.Among them,China's self-developed satellite navigation system,which has been put into use and has developed rapidly,has a wide range of applications in all aspects.Considering the development of satellite communication technology and the multi-band and circular polarization characteristics of BeiDou satellite signals,it has important research significance for multi-band,circular polarization and integrated BeiDou antenna design.This article first elaborates the basic knowledge of the microstrip antenna,working parameters and the way to realize a circularly polarized antenna,then gives the main performance paraneters of the Beidou circular polarized antenna,design index,etc.,finally on the basis of microstrip circularly polarized antena,the low profile and miniaturized Beidou antenna is researched and designed.Secondly,this paper designs antennas covering BDS-2 B1 and B3 frequency bands,using round patches,open slots,crisscrossed slots and electromagnetic coupling feeds,square patch diagonal cuts,and single coaxial feeds.In this paper,the influence of the change of relevant parameters on the performance of the antenna during the antenna design process is given,and the optimal value of the antenna parameters is determined based on theoretical analysis and simulation optimization.The two dual-layer dual-frequency circularly polarized antennas are similar in size.The single-fed dual-frequency circularly polarized antennas have a measured reflectance of less than-10 dB in the 1.25 GHz-1.3 GHz and 1.53 GHz-1.57 GHz frequency ranges and a central axis ratio of less than 3 dB.The radiation pattern is better and the cross polarization ratio is higher than 16 dB.The unit antenna array may form an array antenna with some desired functional application,and it plays an important role in the receiver module of the satellite positioning system.At last,this paper designs a unit antenna for the B1 frequency band.The model is based on the circular antenna structure in the fourth chapter,the U-shaped slot is placed on the patclh,and a smaller size array antenna is realized,and the four units are formed into a square plane.The array uses a multi-section one-to-two T-shaped power divider to implement circular polarization characteristics in a wide band of the antenna by means of non-radiative-edge feeding.The circular polarization arrmy antenna simulation results show that in the 1.51 GHz-1.6GHz frequency range,the reflection coefficient is less than-10dB,the axial ratio of the main axis is less than 3dB,and the angular range of the axial ratio less than 3dB reaches 84°,and the maximum E surface gain is 5.48.dB,although the measured E side of the antenna produces side lobes as high as-13.6dB,and the H-plane maximum radiation pattern deviates from the central axis by 3°,the overall radiation variation trend of the antenna is basically consistent with the simulation results.