Design of a Novel Choke Ring Center-Fed Dual-Band Circularly Polarized Antenna

This paper presents the design of a novel choke ring center-fed antenna. The proposed antenna consists of two layers of microstrip patches, a folded ground plane, two layers of horizontal coaxial corrugated grooves and two layers of longitudinal radial corrugated grooves. Compared with the existing antenna that only adopts the choke ring structure in the horizontal direction, the antenna can effectively reduce the back lobe and improve the backward ratio of the antenna. Simulated results show that the reflection coefficients for the two frequency bands are less than -10 dB, covering GPS L2 (1.195 GHz~ 1.248 GHz) and GPS L1 (1.552 GHz ~ 1.599 GHz). In the entire working bandwidth, the forward to backward ratio of the antenna is greater than 30 dB.