AR bandwidth and gain enhancements of patch antenna using single dielectric superstrate

A single‐feed circularly polarised (CP) patch antenna loaded with a single dielectric superstrate for a wideband high‐gain CP radiation is presented. Along with the gain enhancement, the emphasis is on extra CP radiation of the antenna caused by the superstrate, which broadens the axial‐ratio (AR) bandwidth significantly. A prototype antenna was fabricated and measured at a frequency of 11 GHz. The antenna with overall size of 40 × 40 × 17.45 mm has a voltage standing wave ratio <2 bandwidth of 24.35% (10.1–12.9 GHz), a 3 dB AR bandwidth of 13.6% (10.3–11.8 GHz), a peak gain of 13.17 dBic, a 3 dB gain bandwidth of >26% (10.0–13.0 GHz), and a radiation efficiency of >90%. The presence of superstrate produces a ∼350% increase in 3 dB AR bandwidth and a ∼7 dB increase in the broadside gain relative to the conventional CP patch antenna.