A Design of U-Shaped Slot Antenna With Broadband Dual Circularly Polarized Radiation

In this communication, a novel broadband dual circularly polarized (CP) antenna is presented. This antenna consists of an U-shaped slot to achieve broadband CP radiation and two 50-Ω microstrip-fed ports to realize both right-hand circular polarization and left-hand circular polarization at the same frequency band. The axial ratio bandwidth (ARBW) is greatly broadened by moving the feeding ports to upper portion of the U-shaped slot. To verify this design, the proposed antenna is fabricated and measured. The measured -10 dB reflection coefficient bandwidth is about 114.4% (1.80-6.61 GHz) and the 3-dB ARBW is approximately 110.5% (1.83-6.35 GHz). The isolation between two ports is better than 14.8 dB within the ARBW.