Design Of Multi-Frequency Circularly Polarized And On-Board Omnidirectional Antenna

With the development of the national satellite navigation and positioning system, multi-mode and multi-frequency broadband circularly polarized antenna is also one of the important development direction of navigation and positioning system. Aiming at the hotspot research direction, this paper studies a kind of multi-frequency circularly polarized antenna. At the same time as the satellite navigation system gradually applied to weapons guidance, trajectory and attitude determination and other precision measuring scientific fields, the paper also designed a missile omni-directional antenna.First of all, based on the existing multiband satellite navigation and positioning of the antenna analysis and study, two kind of multi-frequency circularly polarized antenna is designed. Analysis of the impact of the structure and the size of antenna mounted on its performance,and the optimal design was carried out by using HFSS simulation software. Through theoretical analysis and simulation, making the antenna, and tested it. The results show that: the ground station multi frequency circularly polarized antenna in the three frequency points within the main direction of the gain is larger than 2d Bi, the elevation angle of 20 gain greater than 0d Bi, Working within the bandwidth coefficient of voltage standing wave ratio(VSWR) less than 2;Space-borne multi-frequency circularly polarized antenna within the operating bandwidth of VSWR of less than 2, ?60 beam range gain greater than 1d Bi,the low frequency phase center stability is less than 5mm, the high frequency phase center stability is less than 2mm, very good to satisfy the requirement.Secondly, a missile omni-directional antenna is designed. By setting the microstrip antenna array elements to achieve omni-directional radiation and by adjusting the microstrip patch antenna to optimize the performance. Through HFSS designed antenna feed network, finally make the antenna in-kind. The antenna was tested, the results show that the antenna pattern within the working frequency band VSWR is less than 1.5, unit antenna axis ratio less than 3d B, omni-directional antenna array axial ratio less than 6d B. Good antenna horizontal direction, roundness of less than 2d B, the realization of the design requirements of the azimuth plane omni-directional radiation.