Design of wideband circular polarization for the open-slot antenna

An open-slot antenna with wideband circular polarization has been designed and fabricated in this paper. The proposed antenna is composite of an open-slot, an asymmetric structure, and a patch-protruded feeding topology. The asymmetric structure can provide 90° phase difference in order to excite circular polarization for the satellite digital audio radio (SDAR) service system. By utilizing the patch-protruded feeding topology, impedance bandwidth and circular polarization can be enhanced. From the measured results, the proposed antenna achieves a 4.75-GHz impedance bandwidth (133 %) of a reflection coefficient > -10 dB and has a 3-dB axial-ratio bandwidth is about 2.47 GHz.