A wideband and low‐profile omnidirectional circularly polarized antenna

Abstract

AbstractThis article presents a wideband and low‐profile omnidirectional circularly polarized antenna. It consists of a circular slotted top patch connected with a circular ground plane by four shorting vias and eight extended curved branches. These curved branches are introduced around both the patch and the ground plane with proper angle separation, achieving a 90‐degree phase difference between the vertical and horizontal radiating parts. In this way, the wideband circularly polarized characteristic is realized. The final optimized structure is very compact, with a dimension of only 322 × π × 6 mm3 (0.372 × π × 0.07 = 0.03 λ03). Besides, the measured results agree well with the simulated ones, with a simulated/measured impedance bandwidth of 28.4/32.2% and an axial ratio bandwidth of 46.7/42.3% being obtained. And the maximum realized gain is 1.1 dBic, with a gain variation of less than 1.0 dB.