A Novel Wideband Omnidirectional Circularly Polarized Antenna

In this paper, a novel wideband omnidirectional circularly polarized (CP) antenna is proposed. The designed antenna consists of the $2\times 2$ dipoles. The $2\times 2$ dipoles are fed with equal amplitude and phase arranged in circles. And the current directions of the two pairs of opposite dipoles are opposite to each other, which generate the omnidirectional CP. The VSWR of proposed antenna is less than 2 within 4.33GHz-5.38GHz, whose relative bandwidth is 21.6%. The 3-dB axial ratio bandwidth is 4.53-5.84GHz (25.3 %). Due to the omnidirectional radiation of the proposed antenna, the antenna can be used in indoor communications and automotive vehicles mounted antenna.