The low-profile end-fire antenna with circular polarization at S band

This letter presents a low-profile and wideband planar helical antenna to generate end-fire radiation beams. The antenna consists of a small reflective plate, a dielectric support plate and several metal patches. The helix is formed using printed strips with straight-edge connections implemented by metal poles. The profile of the antenna is very low at 0.16λ0 of the center frequency. A broad frequency bandwidth from 2.2GHz to 2.7GHz (25%) for VSWR less than 2 is achieved simultaneously. And the AR bandwidth is from 2.1GHz to 2.7GHz. The direction coefficient of the end-fire antenna in the whole band is above 10dB.