28-GHz band Omnidirectional Lens Antenna for Channel Measurements

This paper presents a novel lens antenna to achieve high and stable omnidirectional gain working at 28-GHz band for 5G millimeter-wave channel measurement applications. The proposed antenna consists of an annular extended hemispherical lens and a small stepped biconical antenna as the feed source, which makes the antenna wide in bandwidth, high and stable in omnidirectional gain. The designed antenna can achieve a -10-dB impedance bandwidth of 22.2% with stable vertical polarized omnidirectional radiation pattern in range of 24 to 30 GHz. The omnidirectional gain is up to 11dBi at 27 GHz, and the rotationally symmetrical structure and feeding ensure good omnidirectional gain stability.