Single-Fed High-Gain Circularly Polarized Microstrip Antenna

In this paper, a single-fed high-gain circularly polarized microstrip antenna is proposed. The circular polarization is obtained by two unequal-length arc-shaped radiation patches, which excite two orthogonal linearly polarized modes with a 90 degrees phase difference. The antenna is excited by coaxial feed. The proposed circularly polarized antenna consists of two arc-shaped radiation patches and a ground plane, which has a simple structure and a higher gain than 10.0 dB. The antenna is fabricated and measured to verify the design. The measured results are in good agreements with the simulated ones. The measured results show that the impendence bandwidth (IBW) for S-11 < -10 dB is 16.7% (3.78-4.47 GHz), and the axial-ratio bandwidth (ARBW) for AR < 3 dB is 3.6% (4.09-4.24 GHz). Further, the gain is higher than 10.0 dB from 4.09 to 4.24 GHz. The antenna radiation pattern performs well over the whole band, and the peak gain can reach 10.67 dB at 4.11 GHz. It is a good candidate for advanced wireless communication systems.