A Bidirectional Same Sense Circularly Polarized Endfire Antenna Array With Polarization Reconfigurability

In this communication, a bidirectional same sense circularly polarized (Bi-SSCP) endfire antenna array with reconfigurable polarization is proposed and implemented. First, a circular polarization (CP) reconfigurable endfire antenna element is realized by adopting two pairs of switchable electric dipoles, which have a 180° phase difference inherently. Along with the fixed magnetic dipole, the endfire antenna element can work at two CP states, i.e., left-hand CP (LHCP) and right-hand CP (RHCP) by switching the states of the two electric dipoles. Then, a Bi-SSCP endfire antenna array with polarization diversity is developed by using two identical endfire antenna elements placed back-to-back with a single feeding probe. For verification, prototypes of the designed endfire antenna element and Bi-SSCP endfire antenna array are fabricated and measured. The measured results show reasonable agreement with the simulated ones. The measured overlapped bandwidth for 10 dB return loss and 3 dB axial ratio of the Bi-SSCP endfire antenna array is from 5.7 to 5.9 GHz for the two CP states.