| Compass satellite navigation system,as one of the world's four major satellite navigation system,can provide all-weather,high precision,high stability,high reliability of positioning,navigation and timing services at any time and place for all types of terminals.Also,the Compass satellite navigation system can provide communication function with respect to the broad application prospect.In the Beidou satellite navigation terminal,the antenna is one of the most important components.Because the performance of the antenna determines the performance of the navigation terminal directly.Now the terminal equipment has the requirements of portability and the space of terminals are limited.The size of the antenna must be more compact.The study of the miniaturization technology of antennas for the application of Beidou navigation system is imminent.The main research contents of this paper include:1.A miniaturized single-band antenna is designed for BDS which can cover the transmit band for BD1 with a single layer.The microstrip antenna structure is miniaturized by loading the grounded metal discs in the microstrip antenna substrate.The circular polarization radiation of the antenna is realized by using different sizes of the metal discs.The measured results show that the antenna size is 0.235?g×0.235?g×0.033Ag and the band of |S11| lower than-10dB is 53MHz(1587-1640MHz).The axial ratio is lower than 3dB and the gain is greater than 2dB at the frequency of 1615.68MHz.2.A miniaturized dual-band antenna is designed for BDS which can cover the transmit band and receive band for BD1 with stacked layers.The meandered ring patch is utilized to achieve miniaturization of the antenna.And then the arc-shaped feeding structure is utilized to achieve impedance matching.At the same time,the good circular polarization characteristics of the antenna are achieved by the special perturbation structure and the L-shaped connecting lines.The measured results show that the antenna size is 0.201?g×0.201?g×0.077?g.And the bands of the |S11| lower than-10dB are 37MHz(1595-1632MHz)and 153MHz(2419-2572MHz).The axial ratio is lower than 3dB and at the frequency of 1615.68MHz.The gain is greater than 4dBi at the frequency of 1615.68MHz and greater than 6dBi at the frequency of 2491.75MHz.3.A miniaturized antenna for BD1(L)/BD2(B1)/GPS(L1)application is designed.Combined with the miniaturization technology in the first two chapters,so that the antenna can achieve L-band for BD1,B1 band for BD2,L1 band for GPS in the single-layer structure.The antenna is made of nested ring patch structure with a compact structure.With the feeding network,the dual circular polarization of the antenna can be easily achieved.The measured results show that the size of the antenna is only 0.254?g×0.254?g×0.035?g and the antenna performance is good and with good engineering feasibility. |
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