Design of a 5G Sub-6 GHz Vehicular Cellular Antenna Element with Consistent Radiation Pattern Using Characteristic Mode Analysis.

A cellular 5G sub-6 GHz vehicle antenna design with a consistent radiation pattern across the frequency bands in 0.617-5 GHz is demonstrated via characteristic mode analysis. The design focuses on maintaining monopole first-order mode radiation pattern over cellular frequency bands and avoiding higher-order modes out of the operational frequency bands to provide optimal performance for automotive requirements. Rather than using an empirical design method, the design procedure in this paper uses the calculated modal significance, characteristic current, modal radiation pattern, and reflection coefficient to define the antenna structure dimensions. The proposed design was simulated, a prototype was measured, and the performance was evaluated on a 1-m ground plane. The antenna has perfect omnidirectionality with a high and stable gain across the frequency range in the 30° area above the horizon.