This paper proposed a wideband antenna for global navigation satellite systems (GNSSs). The antenna has a −10 dB impedance bandwidth of 62.40% from 0.86 GHz to 1.64 GHz, 3 dB axial ratio (AR) bandwidth of 51.30% from 1.00 GHz to 1.69 GHz. Its circularly polarized (CP) bandwidth of 48.48% from 1.00 to 1.64 GHz covers the full band of four GNSSs (GPS, GLONASS, Compass and Galileo). In addition to utilizing higher relative permittivity substrate and adding slots on the radiation patch, a superstrate is also investigated to miniaturize the antenna size.