Advanced monopole antenna with a wide beamwidth for the assessment of outdoor 5G wireless communication environments

We propose an advanced monopole antenna to investigate non‐stationary outdoor wireless channel environments of 5G mobile communications. Our antenna has an omni‐directional beam pattern in the azimuth plane and a wide half‐power beamwidth (HPBW) in the elevation plane, respectively. To minimize blind angles along the axis of the monopole, we intentionally add a metallic annular ring around the monopole, which operates as a secondary source of our antenna. Then, the circumferential field from the secondary source appropriately interferes with the primary field from the monopole to widen the HPBW with a relatively high antenna gain in a far‐field region. An input signal is applied to a standard WR‐28 waveguide, and it is transferred to the monopole antenna through a coaxial waveguide. However, because impedance looking into the monopole and the waveguides are all different, we insert a mode converter between the rectangular and the coaxial waveguides. For better impedance matching, the coaxial waveguide is also used as an impedance transformer between the mode converter and the monopole antenna. Consequently, we can obtain the required omni‐directional radiation pattern with a wide HPBW and a high gain. All measurement data show good agreement with simulations, which proves the validity of our approach.