Single-layer wideband high-gain circularly polarized patch antenna with parasitic elements

This paper presents a single-layer circularly polarized (CP) antenna with wideband operation and high gain characteristics. The antenna consists of a squared patch with a diagonal slot as a primary radiating source and a set of symmetrical multiple squared patches on the same plane as the patch, acting as parasitic elements. The parasitic elements are employed to significantly increase not only the 3-dB axial ratio (AR) bandwidth but also the broadside gain radiation. For a demonstration of the design concept, an antenna prototype with an overall volume of 1.18λ_o × 1.18λ_o × 0.05λ_o (λ_o is the center operating frequency) is fabricated and tested. The detailed design process and the measurements are described and discussed. The measured data indicates that the proposed antenna achieves operating bandwidth of 14.7% (5.05–5.85 GHz) for |S₁₁| ≤ –10 dB and AR ≤ 3 dB. In addition, the fabricated antenna also exhibits high gain radiation from 9.1 to 10.8 dBi within the operating bandwidth.