Design of wideband circularly-polarized double-layer microstrip antenna sub-array

Abstract

Circularly-polarized microstrip antenna is widely used in communication fields. However, conventional microstrip antenna is limited by its bandwidth and axial ratio characteristic. As a result, a 2×2 slot-fed circularly-polarized double-layer microstrip antenna array is proposed in this paper. The design of double-layer structure and corner-cut patch is applied to improve circularly-polarized performance. Impedance matching is well designed by H-shaped slot and microstrip line. The form of rotation array is used to decrease the axial ratio of the array. The simulated bandwidth for VSWR lower than 2.0 of the sub-array is 37.0% in the frequency range of 2.4GHz-3.5GHz, and 10.3dBi gain is obtained at the design frequency. Results obtained based on the proposed analysis can be used in the design of wideband circularly-polarized antenna.