Tri-band antenna with compact conventional phone antenna and wideband MIMO antenna

A tri-band antenna, which consists of a compact conventional phone antenna and a wideband multiple-input multiple-output (MIMO) antenna, is presented for mobile phone application. Three slits etched into the ground plane are used to reduce the mutual coupling between the conventional phone antenna and the MIMO antenna, moreover, this slits are help to relieve the impedance matching degradation of the conventional phone antenna caused by the mutual coupling. A wideband T-shaped neutralization line without effect on the performance of the conventional phone antenna is applied to improve the isolation for the MIMO antenna, and high isolation is achieved within the wide operation band. For the convention phone antenna, the two operation bands with VSWR ≤ 3 are 0.89-0.96 GHz and 1.71-2.18 GHz, respectively, and nearly omnidirectional radiation patterns in H-plane are achieved. The operation band of the MIMO antenna with VSWR ≤ 1.7 and isolation ≥ 20 dB is 2.4-3.7 GHz, and the two MIMO antenna elements have back-radiation patterns for achieving diversity gain. The simulated and the measured results are in a good agreement.