Polarization-rotating zeroth-order-resonator antenna with voltage-controlled reflectors at both ends

Polarization-rotating zeroth-order-resonator (ZOR) antenna with voltage-controlled reflectors at both ends is proposed and experimentally demonstrated. The resonator antenna is composed of a microstrip-line-based CRLH transmission line with reactance loads at both ends. The resonant condition is satisfied when the impedance of one load is the complex conjugate of another. Voltage-controlled reactance loads were designed and fabricated by using varactors. By changing bias voltages applied to varactors, resonant states were controlled which include dominant series resonance in series branch, dominant parallel resonance in shunt branch, as well as the hybrid states with double resonances, without changing any configuration parameters in the CRLH line section. It was experimentally verified that by electronically changing terminal condition, the co-polarization direction of the linearly-polarized radiation was continuously rotated.