The Research And Design Of Multiband Antenna Based Beidou Satellite Navigation System

With the rapid development of Beidou Navigation Satellite System,the demand for user terminal equipment is becoming more and more widely.Considering the requirements of terminal equipment portability,circular polarization characteristic of satellite signals and multi-band signal transmission of Beidou System,the antenna of portable terminal device should also have the characteristics of miniaturization,multi-band and circular polarization.Therefore miniaturized multi-band circularly polarized antenna occupies a very important position in Beidou user terminal equipment.Based on the analysis and comparison of the typical Beidou antenna design method,two miniaturized multi-band circularly polarized microstrip antennas are proposed.A two-layer patch Beidou antenna is designed,having two relatively independent feed points,two circular patch structures and covering two bands BDS-2 B2 and BDS-1 S.By using the slotting method on the circle patch,circular polarization can be realized.Based on the commonly used feeding method,two independent feeding point are used and the metallized hole is introduced to increase the port isolation of the two common-grounded feeding ports.Four unequal length slits are cut on the edge of the circle patch to achieve miniaturization.Through calculation and software optimization,the different effects of the main structural parameters of the antenna on the performance were analyzed.Based on these analysis conclusions,the size of the antenna was determined to be 70 mm×70 mmX3.2 mm.Compared with the same kind of antennas,the proposed antenna covers the two bands of Beidou system and the size is reversely reduced.A single-layer patch Beidou antenna is proposed.The antenna has a single feed point and a single circular patch structure,and covers the BDS-2 B1 and BDS-1 S bands.By introducing perturbation of the slit onto the center of the circular patch,circular polarization can be realized.At the same time,the C slots is introduced to further reduce the volume of the antenna.The final size of the antenna is 50mm × 50mm X 1.6mm.Compared with the same kind of antenna,the proposed antenna covers the double bands of Beidou system and the size is reduced.The simulation results show that the two Beidou antennas meet the requirements of the Beidou system for terminal equipment:The two-layer patch Beidou antenna has an axial ratio of 1.119dB and a gain of 1.69dB in the B2 band,the axial ratio in the S band is 0.82 dB,and the gain is 1.74 dB;the axial ratio of the single-layer patch Beidou antenna in the Bl band is 0.89 dB and the gain is 1.7 dB,in S band the axial ratio of is 1.02dB and the gain is 1.6dB.