A Novel Low Axis Ratio Double-Circularly Polarized Microstrip Antenna

This article presents a dual circular polarization (CP) microstrip antenna, emitting electromagnetic waves above and below the substrate, which is fed by the double L-probe. Selecting the L-probe feed increases the bandwidth of the antenna, and different probes control the rotation of CP. The antenna could radiate two polarized waves of the same amplitude and vertical through two square radiation patches; meanwhile, adjusting the phase difference between both waves to 90 degrees will produce a CP wave in the far-field. The simulation and measurement results show that the antenna is in 4.3-4.8 GHz band with S11<-10 dB, S22<-10 dB, and AR<3 dB. Furthermore, a lower axis ratio could be obtained in this work compared with similar antennas of the same type.