A novel unidirectional circularly polarized antenna

This paper presents a novel type of unidirectional circularly polarized (CP) antenna. The antenna constructively combines a dipole and a half loop radiator. Theoretical foundation and working principle of the antenna is firstly discussed. A practical design of right-handed circularly polarized antenna with differential feeding is then presented. Measurement results show that the proposed antenna can achieve a 3-dB axial-ratio bandwidth of 24% (from 5.9 to 7.5GHz), which is within its −10-dB differential reflection bandwidth. Meanwhile, the right-handed circularly polarized gain within the axial-ratio bandwidth is up to 7.0 dBi.