Broadband CPW-fed circularly polarized antenna with machine-gun-shaped feeding line and symmetric-aperture

This paper presents a new design for wide slot circularly polarized(CP) antenna (WSCPA). Compared with existing WSCPA, the proposed design possesses much wider return loss S _{11} bandwidths and CP bandwidths. The main features of the antenna structure include a machine-gun-shaped CPW feeding line and a wide symmetric-aperture along the diagonal axis. Wideband return loss and CP radiations have been achieved by properly tuning circular-shaped aperture and feeding line. The measured bandwidths of 10 dB return loss and 3 dB axial ratio (AR) are around 110.2%(2.2–7.6 GHz) and 105.9% (2–6.5 GHz), respectively. Throughout this letter, the improvement process of the AR and S _{11} properties is completely presented and discussed.