A 4-element MIMO antenna with orthogonal circular polarization for sub-6 GHz 5G cellular applications

A multiple-input-multiple-output (MIMO) antenna with orthogonal circular polarization (CP) is proposed in this paper with an intention to use the antenna in sub-6\ua0GHz 5G applications. The single antenna consists of a radiating slot and feed\ua0line. The non-uniform width elliptical ring slot in the ground plane and unequal feed\ua0line technique are used to produce CP. The benefit of using ring slot antenna is that this type of antenna can radiate orthogonal CP at the front and back direction, simultaneously. The operating band of single antenna is (3.6–3.8\ua0GHz). The MIMO antenna has 4 single antenna elements where each antenna element is surrounded by the mirrored antenna elements. As a result, MIMO structure provides orthogonal CP. Moreover, this MIMO antenna can also radiate both LHCP and RHCP on the both directions (θ = 0° and 180°) simultaneously. Three interconnected strip lines on the ground plane are designed to connect the individual grounds of the antenna elements. The MIMO antenna provides good isolation and CP gain in the whole band (3.4–3.8\ua0GHz). The envelop correlation coefficient and channel capacity loss are evaluated to judge the MIMO performances and promising result is achieved. To analyze the impacts of user hand, various performance studies are done for the antenna in the vicinity of left hand and right hand phantom model and satisfactory results are achieved. These performances prepare the antenna more attractive to use in 5G cellular applications