Surface Current Optimization of Dipole Antenna Close to Ground Plane for 5G Mobile Applications

When a dipole is placed close to a ground plane, the induced currents on the ground plane are opposite to dipole currents making the entity a poor radiator. This paper presents a dipole antenna design at the ground distance of only 0.5 mm (0.04λ0 at 25 GHz). The dipole-ground interaction is tuned with reactive loading so that induced currents on the ground and those on the dipole arms contribute additively in the far field. Thus, the radiation efficiency is significantly improved when the total current reaches the peak. The value of the components are obtained through a quick circuit optimization and can be easily converted to a discrete form. This method is verified in the simulations with both the lumped and discrete elements. The results show that the proposed antenna has reached a good radiation efficiency, realized gain, and impedance matching at 25 GHz.