A Flat-Gain Array Antenna Comprising Disparate Elements Designed for 5G Applications

A planar array antenna consisting of a patch antenna fed by a coplanar waveguide (CPW) and a patch antenna excited through near-field coupling is presented. The utilization of a mixed-mode feed line, which incorporates both direct and indirect feed lines, enables radiating elements to resonate at two distinct frequencies. The feed network delivers an electric current to one patch antenna through a metalized via, whereas a surface equivalent magnetic current is induced in the other patch antenna through near-field coupling. Resonance occurs at 26 GHz after balanced series stubs are added to the feed line. To achieve a flat gain response, a notched slot is positioned between the locations of the electric and magnetic current sources. The measurement results of the antenna show a flat gain response covering an impedance bandwidth of 16.45% (25.1–29.6 GHz), which fulfills the 26 GHz and 28 GHz bands of fifth-generation (5G) mobile communication systems.