Broadband Slot Antenna with Circular-Polarization Operation

In this paper, a novel wideband circularly polarized slot antenna is presented. The slot antenna with four microstrip line feeds orientated to have phases of 0deg, 90deg, 180deg and 270deg, using a feed network comprising a pair of broadband 900 hybrid was found to deliver a measured impedance bandwidth of 77.8% from 1.02 to 2.32 GHz for SWR<2, measured 2-dB and 3-dB axial-ratio bandwidths of 51.4% from 1.3 to 2.2 GHz and 88.9% from 1 to 2.6 GHz, respectively, and a measured gain bandwidth of 33% from 1.5 to 2.1 GHz for gain>3dBi. The simulated impedance bandwidth is 89.1% from 1.02 to 2.66 GHz for SWR < 2. The simulated 3-dB axial-ratio bandwidth is 81% from 1.1 to 2.6GHz. The simulated gain bandwidth is 27% from 1.6 to 2.1 GHz for the gain > 3dBi. Good agreement is observed between simulation and measurement.