Dual-Band Dual-Sense Circularly-Polarized Antenna Utilizing a Radiating Slot Antenna as Feeding Structure

This letter proposed a new approach to design a dual-band dual-sense circularly-polarized (CP) antenna by reusing the feeding structure as a radiating slot antenna. The antenna is a microstrip-line-fed, slot-coupled magneto-electric dipole (ME-dipole) antenna. Different from conventional ME-dipole antennas, the coupling slot in this work not only functions as the feeding structure, but also operates as a radiating slot antenna. As a result, the ME-dipole radiator and the feeding slot can be modified to generate left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) waves, respectively. The proposed design minimizes the requirement of using two antennas for two bands. To validate the design, the antenna is implemented and experimental results demonstrate satisfactory CP characteristics. The dual-band impedance bandwidths are 18.2% (2.14-2.57 GHz) and 17.8% (3.78-4.52 GHz). The LHCP and RHCP axial ratio (AR) bandwidths are 21.3% (2.26-2.80 GHz) and 25.9% (3.3-4.28 GHz), respectively