A Circularly Polarized Planar 2×2 Dipole Array Antenna Fed by a Modified 4-way Gysel Power Divider

In this paper, a circularly polarized high gain planar 2×2 dipole array antenna for WLAN, RFID, radar, and satellite communication applications is proposed. The proposed array antenna consists of four planar dipole antennas and a modified 4-way Gysel power divider. The antenna uses 3 stacked metal layers and a metal reflector under the antenna boosts overall antenna gain. The size of the designed antenna on FR4 substrate was 150 mm × 150 mm × 20 mm (1.25λ0 × 1.25λ0 × 0.17λ0) including the reflector. The designed antenna had left hand circular polarization (LHCP), and its measured circular gain value was 8.7 ~ 9.62 dBic at 2.4 ~ 2.6 GHz. The measured axial ratio (AR) was 0.3 ~ 2.2 dB at the same frequency band of interest.