Phased Arrays and MIMO: Wideband 5G End Fire Elements on Liquid Crystal Polymer for MIMO

Abstract

This paper presents a multiport antenna for mobile communications at a symposium on phased arrays, and consequently it has two parts. Firstly, we review the context of the phased array antenna as a general array and multi-element antennas (MEAs) which are prevalent in mobile communications. There is overlap between phased arrays and MEAs in terms of the basic array principle, but the design approaches and typical applications are different. These differences are reviewed to help fix ideas about the terminology. The second part presents a new array antenna for fifth generation (5G) mobile communications. Its elements are wideband designs for end-fire radiation from the edge of a metallic platform, or chassis. Each element comprises a pair of different sized dipoles in a parallel configuration in order to achieve a wideband impedance bandwidth. The conducting dipoles are supported by a dielectric, which is Liquid Crystal Polymer (LCP). This has relatively low dielectric losses at millimeter-wave frequencies, resulting in an antenna radiation efficiency of more than 90% across a 63 % relative bandwidth. The frequency is from 22.8 GHz to 44 GHz which covers the recently- released 5G bands at 24, 28 and 38 GHz. The elements sit on the edges of a rectangular chassis and are directive away from these edges. The end-fire gains are more than 6 dBi. The elements are well-spaced because the electrical size of the chassis is sufficiently large, meaning that the mutual coupling within the basic design is very low, but can be even further decreased using decoupling configurations.