Four-element Reconfigurable Coupled Loop MIMO Antenna Featuring LTE Full Band Operation for Metallic-rimmed Smartphone

Abstract

This paper describes a low-profile 2×2 Multi-Input Multi-Output (MIMO) antenna system that is fully functional over the entire Long-Term Evolution (LTE) spectrum 699–960 MHz (lower frequency spectrum) and 1710–2690 MHz (higher frequency spectrum) that is applicable to real-life metallic smartphone platforms. The presented methodology entails utilizing the longitudinal edges of the ground plane amid an extremely narrow ground clearance of 2 mm. The metallic frame of the smartphone is utilized along with a stub network to devise a reconfigurable coupled loop antenna topology. The proposed 2×2 MIMO antenna configuration is measured and confirmed to exhibit efficient Envelope Correlation Coefficient (ECC) (<0.5) and one of the highest radiation efficiencies to be reported in literature across the entire LTE spectrum.