Circularly-Polarized Shaped Pattern Planar Antenna for Aerial Platforms

Abstract

Circularly-polarized planar antenna with a shaped pattern for airborne applications, is proposed in this letter. The proposed antenna consists of vertically-polarized formation and horizontally-polarized stubs to provide circularly-polarized configuration, which is loaded by a copper curl based top layer to control current distribution for beam shaping and filling of zenith null. The antenna also contains split ring resonators beside partial ground to make it deployable over larger ground planes (metallic bodies) without distorting circular polarization by controlling phase of reflected waves. The power density of presented airborne shaped pattern antenna differs for variant elevation and azimuth angles, to have uniform wireless coverage over the earth's surface by managing variations of the signal strength because of different path lengths. The demonstrated antenna also possesses circular polarization and direction based circular polarization diversity at angles against the greatest path-lengths. Antenna retains a null-filled pattern in the vertical plane along with having high absolute peak gain (5.5 ± 1 dBi) and adequate peak polarization gain (2 to 4 dBi) through-out the operational bandwidth from 2.82 GHz to 2.89 GHz (Measured reflection coefficient less than -10 dB). Moreover, the radiating element exhibits omnidirectional radiation characteristics, with good horizontal gain (greater than -3.6 dBi).