A Circularly Polarized Array Antenna for GPS Application

The paper proposes a 2×2 array antenna for GPS (Global Positioning System) application in the L1 band (1.575 GHz). In which, the element antenna is a square patch antenna with a diagonal slot in the middle to create circular polarization (CP). The element antennas are fed sequential-phase feeding network to reduce the size of the array antenna. To extend the 3 dB axial ratio (AR) bandwidth (BW), parasitic patches are added to either side of the main radiating patch of the element antennas. The antenna is designed using FR-4 material with compact size of 182×182×1.6 mm3, impedance BW 62.2 MHz (3.95 %), 3 dB AR BW 30.3 MHz (1.92%) and high gain 10 dBi. Especially, the polarization isolation between the right-handed CP (RHCP) and left-handed CP (LHCP) is higher than 24 dB. These results show that the proposed antenna is really effective for GPS applications.