Design of planar wideband MIMO antenna for mobile phones

This paper presents a dual-port planar multiple-input-multiple-output (MIMO) antenna with wide bandwidth. The proposed MIMO antenna element consists of a monopole and a step impedance resonator (SIR) stub which extends from the ground and is coupling fed by the monopole. A slot is etched on the ground and a neutralization line is connected with the two antenna elements for decoupling. The simulated results show that the MIMO antenna achieves a wide bandwidth of 105.7% from 0.87 GHz to 2.82GHz, fully covering the 2G bands of GSM900/ GSM1800/GSM1900, 3G bands of TD-SCDMA/WCDMA/ CDMA2000 and most of the 4G (LTE) bands. The isolation is better than 12.5 dB in the lower band and 15dB in the higher band. Besides, the envelope correlation coefficient and mean effective gain are also studied. The planar structure and good diversity performance make the MIMO antenna very suitable for mobile terminals like smart phones.