Wideband circularly polarized dipole array using a sequential-phase feed

This paper presents a planar 2 × 2 dipole array in a square contour fed by a wideband sequential-phase network. The array, with an overall size of 80 mm × 80 mm × 1 mm, resulted in a |S
₁₁
| <;-10 dB bandwidth of 1.35-1.85 GHz (31.25%) and a 3-dB AR bandwidth of 1.51-1.87 GHz (21.3%). The array radiated a bi-directional electromagnetic wave with a gain excess of 3.5 dBic for both broadside and backside radiations. The radiation efficiency was better than 90% across the operational bandwidth.