A low-profile, wideband, vertically-polarized antenna with directional radiation patterns in the azimuth plane

A low-profile, wideband, vertically-polarized antenna with directional radiation characteristics in the azimuth plane is proposed. The antenna is composed of four half-loops with the shape of bent diamond arms that are fed at the center and short circuited to the ground plane at their ends. Two of the loops are fed in phase and the other two are fed out of phase. Then, these two antenna arrays are fed using a proper feed network to obtain a cardioid-shaped radiation pattern over a very large bandwidth (6:1). The antenna has electrical dimensions of 0.77λ_min × 0.77λ_min × 0.09λ_min at its lowest frequency of operation.