Abstract: Satellite navigation systems require the antenna to provide wide beam, circular polarization and high gain at low elevation. Based on these needs, a new type of balun for quadrifilar helix antenna is designed. The structure of the balun is realized by cutting four splits with regular length on the outer conductor and adopting integrated design for the outer conductor, the balun structure and the electrical connector. The two ends of the four spiral arms are respectively connected to the feed end and the non-feed end of the outer conductor. The 90° phase difference is only produced by the balun structure and the antenna pattern is only produced by the four spiral arms. Therefore, the difficulty of design and debugging of the antenna are reduced. The experimental results show that the antenna can provide good characteristics of wide beam and circular polarization.