Dual-Band Inverted F-Shaped Antenna Array for Sub-6 GHz Smartphones

Abstract

In order to meet the requirement of dual-band MIMO operation in 5G smartphones, a 12-port dual-band inverted F-shaped antenna array for 3.5 GHz (3400- 3600 MHz) and 5.8 GHz (5725-5785 MHz) bands is designed. The proposed dual-band antenna array elements are located symmetrically on the inner surface of side frames instead of on the circuit board. Thus, the structure without ground clearance along the long edges is suitable for wide-screen smartphones. To embed 12 antenna elements into the limited space of a smartphone without additional decoupling structures, we propose a structure that bend the branches of inverted-F antenna to a smaller size (8mm×6mm) reducing the occupied space of antennas. A prototype of the proposed 12-antenna array is manufactured and measured. Both simulation and experimentally measured results show that our designed antenna array achieves desirable antenna impedance matching (better than 6/10 dB return loss), acceptable isolation (better than 10 dB) and antenna efficiency (better than 40%). Envelope correlation coefficients and channel capacities are also calculated to validate that the proposed dual- band antenna arrays have good radiation and MIMO capacity performance.