Dual‐square‐ring‐shaped slot antenna for wideband circularly polarized radiation

A compact dual-square-ring-shaped slot antenna using a microstrip feed line is proposed for wideband circularly polarized (CP) radiation. The antenna consists of a combined dual-square-ring-shaped slot along the diagonal direction and a microstrip feed-line along with stub in the orthogonal direction. The slot and feeding structures are fabricated on the opposite planes of a low cost FR4 substrate. The stub width and a dual-square-ring-shaped slot are optimized for wideband CP radiation with good impedance matching. The measured 3-dB axial ratio and 10-dB return loss bandwidths of the proposed antenna are 47% (2.1–3.4 GHz) and 75% (1.92–4.25 GHz), respectively. The measured gain is more than 2.0 dBic over the 3-dB axial ratio bandwidth. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2645–2649, 2014