Dual-Broadband Circularly Polarized Reconfigurable Antenna Based on Asymmetric U-Slot Patch

A novel dual-broadband circularly polarized (CP) reconfigurable antenna and its 2 x 2 array are presented in this letter. The proposed antenna is realized based on the double asymmetrical U-slots patch, and the dual-band sequential rotation technique is utilized to achieve a dual-broadband 2 x 2 arrays. The dual-band CP (DBCP) radiation characteristic of the patch is discussed based on the mode behaviors predicted by characteristic mode analysis. The switchable DBCP is achieved by asymmetrically controlling the diodes installed on the arms of two U-slots. To further improve the axial ratio (AR) performance, a 2 x 2 array with reconfigurable dual-band feeding networks is designed based on the sequential rotation technique. The measured results show that the array has wide 3 dB AR bandwidths of 28.4% and 16.0%, with wide 3 dB gain bandwidths of 23.8% and 18.2%, respectively.