A Wideband PIFA-Pair-Based MIMO Antenna for 5G Smartphones

In this letter, a multiple-input–multiple-output (MIMO) antenna with wideband performance for 5G smartphones is presented. First, a planar inverted-F antenna (PIFA) with an inverted-T-shaped open-slot is introduced. The proposed PIFA operates with a wide bandwidth of 78% due to the multimode technology. Then, two such PIFAs are attempted to be merged as a PIFA-pair, constituting a 2 × 2 sub-MIMO antenna with a similar bandwidth as the PIFA-element. Additionally, the isolation between two PIFA-elements in a PIFA-pair is higher than 10 dB across the broadband. Finally, a 4 × 4 MIMO antenna, which is composed of two PIFA-pairs, is demonstrated to cover the 5G NR frequency bands: n77/n78/n79 and LTE band 46. The simulated and measured results are included for illustrating the performance of the proposed MIMO antenna.