Novel 2 × 2 square slot circularly polarized antenna array with wideband characteristics

Abstract

In this paper, a novel 2 × 2 square slot wideband circularly polarized antenna array (CPAA) is proposed. The antenna consists of a sequential rotation feeding structure, four asymmetric U-shaped feeding strips and a slotted ground plane formed by four square slots with cut corners, four rectangular slots, and four L-shaped strips. In contrast to the traditional L-shaped feeding strips used in CPAAs, an asymmetric U-shaped feeding strip is, for the first time, presented to improve the antenna performance. By using these strips and slots as perturbation elements, the slotted CPAA is able to stimulate multiple circular polarized (CP) radiation modes, resulting in wideband CP radiation. The measured results revealed that the 3-dB axial-ratio (AR) bandwidth for AR < 3 reached 81.3% (1.75–4.15 GHz), whereas the −10-dB impedance bandwidth (|S11| < −10 dB) reached 88.6% (1.96–5.08 GHz).