A CPW-Fed Broadband Circularly Polarized Monopole Antenna with Parasitic Open Loop

A simple and compact broadband circularly polarized (CP) monopole antenna with coplanar waveguide (CPW) feeding is proposed in this paper. The antenna is composed of a knife-shaped monopole, a circular-ring with a gap at the bottom, and an asymmetric ground plane. CP radiation might be produced by combining an asymmetric ground plane with a monopole. Then, a parasitic open loop is added to achieve broad CP characteristics and a wide impedance bandwidth. The simulated antenna provides -10 dB impedance bandwidth (IBW) of 113.1% ranging from 2.19 to 7.89 GHz, and the 3-dB axial ratio (AR) bandwidth of 77.4% ranging from 2.65-6 GHz. In addition, it provides 72.7% of 2-dB AR bandwidth in the range of 2.75 to 5.89 GHz. The performances with different parameters are analyzed. The proposed antenna can be applied to a variety of wireless communication scenarios.