MIMO Antenna System with Pattern Diversity for Sub-6 GHz Mobile Phone Applications

Abstract

A MIMO antenna system is designed and presented for sub-6 GHz mobile phone applications. The proposed antenna design consists of six loop-type radiation elements. From the six elements, four elements are placed at the corners of the mobile phone PCB by following pattern diversity configuration, while the rest of the two elements are placed in the center of the PCB. Furthermore, a $50\Omega $ coaxial connector is utilized to feed the antenna elements. From the presented results, it is demonstrated that the elements placed at the edges are resonating at 2.5 GHz, and the center placed elements provide resonance at 3.5 GHz. Moreover, according to S11 ≤ -6 dB, the impedance bandwidth for both the bands is 790 MHz (2.3-3.09 GHz) and 1.18 GHz (2.99-4.17 GHz), respectively; while for S11 ≤ -10 dB, the impedance bandwidth for both the bands is noted to be 340 MHz (2.38-2.72 GHz) and 650 MHz (3.17-3.84 GHz), respectively. A gain of more than 4 dBi and >85% radiation efficiency are achieved for the single radiation element. The presented antenna design also provides sufficient radiation coverage supporting different sides of the mobile phone PCB. In addition, the effects of the human hand and head on antenna's performance are studied and it was observed that the proposed antenna system provides acceptable properties in the data mode and talk mode.