| Under the technical conditions of modern satellite navigation system,many error sources can be eliminated or mitigated by difference technique or model correction.The multipath effect has become an important source of error.Thus,the anti-multipath capability of the antenna is essential for high precision GNSS Application.In the design of an antenna,the miniaturization is a difficult point,especially for high precision surveying antenna which is always fabricated with a huge floor structure to ensure the anti-multipath performance.Therefore,the miniaturization design is of great significance for high-precision surveying antenna.Taking into account the current wide navigation band distribution,high-precision surveying antenna is required to cover all the L navigation band,and have a strong anti-multipath capability.This paper focuses on highprecision satellite navigation receivers and aims to design a miniaturized antenna that achieves the technical requirements of GNSS high-precision surveying antennas.In this paper,high precision GNSS antenna and anti-multipath structure have been studied,the main research results are as follows:(1)Illuminates the principle of multipath-generating scene and antenna antimultipath,and introduces choke ring technique and saw-tooth structure.A miniaturized anti-multipath structure is proposed,including a vertical choke ring,a bottom cavity and a saw-tooth structure.The vertical choke ring is also based on the choke ring theory,but it is placed under the antenna rather than around the antenna as traditional choke ring,although the anti-multipath capability is weaker than the traditional ones,but the size is greatly reduced and the low elevation gain is strengthened;the bottom cavity is designed to place the feed network,low-noise amplifier,and filters,simulations show it can improve anti-multipath capability of and near L5 band;saw-tooth structure can significantly enhance the anti-multipath capability of the antenna,but will damage the antenna circular polarization characteristic.With the help of a more mature GNSS antenna design,the influence of the parameters of the miniaturized anti-multipath structure on the front-to-back ratio and the axial-ratio of the antenna is analyzed in detail in the electromagnetic simulation software CST.The results show that the shape,size,position and attitude of the structure can be optimized to take count of higher front-toback ratio and better axial-ratio.After optimizing,the miniaturized anti-multipath structure can be used for high-precision surveying antenna.(2)In order to realize the wide band coverage of the antenna,a four-feed triangledipole antenna is proposed.On the basis of traditional microstrip patch antennas,triangular dipole antennas are symmetrically arranged with four triangular patches,and the patch is fed with rotating phase coaxial feeders respectively,and a miniaturized anti multipath structure is installed.After simulation and verification,the antenna can cover all existing L navigation bands with a stable phase center(within 2mm),excellent antimultipath performance,and good circular polarization characteristics which achieves the technical specifications of GNSS high precision surveying antennas.The antenna's gain,anti-multipath capability,and circular polarization characteristics reach an equivalent level comparable to that of a conventional high-precision surveying antenna.At the same time,the volume is reduced by more than 50% and a wider beam-width and a relatively high low elevation gain are reached,which facilitates the capture of low elevation angle satellite signals.Finally,the research results of the paper and its application are summarized,and the work to be carried out in the next step is prospected.The research results can provide technical reference for the development of the measurement receiver antenna of Beidou navigation satellite system. |
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