Wideband High-Gain Omnidirectional Biconical Antenna for Millimeter-Wave Applications

A novel omnidirectional biconical antenna for millimeter-wave (mm-wave) wireless communications is investigated. It is loaded by an annular metal lens that consists of rotationally symmetric annular metal plates. A nearly uniform E-field distribution can be obtained at the radiating aperture across a wide frequency range, giving a wideband high-gain omnidirectional antenna. The operating principle and design flowchart of the lens are given. To validate the idea, a Ka-band vertically polarized prototype was fabricated. Both its measured -10 dB impedance and 3 dB gain bandwidths are 43.9% (25.6-40.0 GHz), with the maximum measured gain given by 9.2 dBi. As compared with the conventional biconical antenna, our antenna can obtain a higher gain by ~4 dB across the entire impedance passband.