Abstract: In this paper, a wideband circularly polarized slot helix antenna is proposed. The antenna is printed on the inner and outer surfaces of a square columnar structure with FR4 dielectric substrates. Two sets of helical slots are etched on the outer surface of the substrate, and the end of the slot is extended to the top surface of the proposed antenna. The feedline is a folded microstrip line that is printed on the inner surface of the dielectric substrate, and the wide impedance bandwidth and axial ratio bandwidth of the antenna are obtained with coupling feeding of every slot. The antenna size is 0. 111λ0 ×0. 111λ0 ×0. 221λ0 (λ0 is the free-space wavelength at the center frequency of Beidou B2). The test results show that the S11≤-10 dB bandwidth is 1. 158-1. 778 GHz and the axial ratio (AR)≤3 dB bandwidth is 1. 133-1. 918 GHz. The proposed antenna adopts a slot helix structure and has a small dimension, a wide impedance bandwidth and axial ratio bandwidth with a simple feed network and can find applications in satellite navigation systems.