A Reconfigurable Circularly-Polarized Ring-Slot Antenna Employing Microstrip-Line Switchable Feed Network

This paper proposes a new ring-slot antenna employing a microstrip-line switchable feed network for circular polarization (CP) reconfigurable capability. For switchable functionality, diodes are incorporated between the center patch element and microstrip lines. Since the microstrip lines are used as a switchable feed structure to couple the ringslot antenna on the ground plane, a simple configuration with no additional bias networks is realized. The CP reconfigurable property can be enabled by applying the switching voltage to the diodes. The measured results show that 10-dB impedance bandwidth of15.8% and 17.5%, the axial ratio of lower than 3 dB, and the cross-polarization level of better than 20 dB for LHCP and RHCP are respectively acquired.