Circularly polarized antenna with folded ground and parasitic branch for 60GHz WLAN

In this paper, a circularly polarized (CP) antenna with a broad axial ratio (AR) bandwidth for 60 GHz communication. The vertically polarized wave and the horizontally polarized wave are radiated by using a folded ground structure and a parasitic branch, respectively. The CP wave is completed by merging two orthogonally polarized waves. Conventional printed circuit board lamination is used to create the antenna element topology consisting of a folded ground structure and parasitic branch and then 4 × 1 array is fabricated and measured. In measured results, it is confirmed that the antenna has the AR bandwidth of 8 GHz and the peak gain of 9.5 dBic. Finally, the measured results show the good agreements with the simulated ones.