Mutual Coupling Reduction of Slot Array Antenna for 5G Millimeter-wave Handset

A planar switchable phased array has been proposed for 5G handset terminals at 28 GHz. It consists of three subarrays. Each subarray contains eight radiating slots. The three subarrays share the same ground plane and can steer their beams to three distinct regions. By switching between the three subarrays, a three-dimensional (3-D) coverage of the terminal is obtained. However, the array suffers from relatively high mutual coupling. Hence, in this work, an effective decoupling technique is proposed to reduce the mutual coupling between adjacent elements of each subarray, while preserving the matching conditions and radiation characteristics of the original handset array. The isolation within each array is enhanced more than 5 dB, achieving an isolation larger than 18 dB at the center frequency, resulting in smaller active reflection and larger scanning angle.