Broadband Series-fed Circularly Polarized Microstrip Antenna Array

In this paper a broadband series-fed circularly polarized microstrip antenna array is proposed. The series fed array consists of four sequentially rotated circular micro-strip antenna connected to a circularly polarized patch antenna. The center patch is fed by two orthogonal L-probes with 90° phase shift between them. In addition, four sequentially rotated parasitic patches which resonates at higher frequency band are coupled to the center patch. The parasitic patch improves the axial ratio and gain of the antenna at higher frequency band. The impedance bandwidth of the antenna is from 3.77-6.30 GHz (50.2%). The axial ratio <; 3 dB bandwidth of the antenna is from 3.77-5.85 GHz (43.2%). The maximum gain of the series-fed CP antenna array is 12.1 dBi.