In global navigation satellite systems (GNSS), the receivers are vulnerable to the inevitable interferences, which may even result in acquisition failure. This paper mainly focuses on the study of miniaturized circularly polarized (CP) antenna for anti-jamming navigation systems. Firstly, a new method for size reduction and axial ratio (AR) beamwidth enhancement is proposed. It is revealed that by etching slots on the patch and loading capacitive patches, the footprint of the patch is significantly reduced to 0.18λ₀×0.18λ₀. In addition, the simulated 3-dB axial ratios beamwidth is wider than 120o . Then, an array consisting of thirteen elements is designed, and the anti-jamming algorithm based on the linearly constrained minimum variance (LCMV) criterion is applied. It is shown that the proposed antenna array can effectively suppress the interferences from different directions simultaneously, which validates the proposed design a good candidate for anti-jamming navigation systems.