Broadband CPW-Fed Circularly-Polarized Slot Antenna With an Open Slot

A novel broadband CPW-fed circularly-polarized slot antenna with an open slot is presented. The broadband circular polarization can be achieved simply by opening the radiation slot at the lower left of slot. From the experimental results, the 3-dB axial-ratio bandwidth can reach as large as 1000 MHz (27% relative to the center frequency of 3700 MHz) which can cover the 3.3-3.8 GHz WiMAX band. In addition, the proposed design has the VSWR ≤ 2 impedance bandwidth of 5330 MHz (111% relative to the center frequency of 4795 MHz) which can cover the 2-6 GHz WiMAX band. The proposed antenna also has a peak antenna gain of about 5.3 dBic and gain variations can be less than 1 dBic for frequencies within the CP bandwidth.