Dual-band Circularly Polarized Aperture Coupled Annular-ring Microstrip Antenna for GNSS Applications

In this paper, a dual-band circularly polarized stacked annular-ring microstrip antenna which covers the bands of Galileo (E5a, E5b, E1, E2, L1), GPS (L1, L2, L5) and GLONASS (L1, L2, L3) is presented. The antenna is composed of two concentric annular-ring patches that are etched on a substrate to generate a dual-band response. Four H-shaped apertures are added to improve the coupling between the microstrip lines and rings. And a wide-band feeding network is used to broaden the axial-ratio bandwidth. Good agreement is achieved between the simulation and measurement, which shows that the return loss of the proposed antenna is less than -15 dB in the whole band and the 3-dB axial-ratio (AR) bandwidths for the lower and upper band are 12.5% and 20.8% respectively. The measured results confirm the validity of the designed antenna which is suitable for Global Navigation Satellite System.