Dual-band circularly polarized antenna with low observation angle performance enhanced for GNSS applications

A dual-band circularly polarized (CP) antenna with a broadband feeding network that covers the bands of GPS (L1, L2, and L5), Galileo (E5a, E5b, E1, E2, and L1), and GLONASS (L1 and L3) is introduced. This antenna uses the miniaturized feeding network to reduce its size, which is only about 0.26λ × 0.26λ × 0.08λ. It also has another advantage of good axial ratio (AR) and gain performance in the low observation angles. The strip line with three wideband baluns is adopted in the feeding network to achieve good AR bandwidth (more than 50%) and VSWR bandwidth (about 51%). The measured gain is higher than 1 and 3 dBi in the lower and higher bands, respectively. The measured results verify the dual-band CP operation and confirm the validity of this design which meets the requirements of global navigation satellite system applications.