Abstract:A dual-band broadband Multiple-Input Multiple-Output(MIMO) antenna is proposed. The antenna is coupled fed by microstrip line and has an annular aperture on the surface. The wide gap and narrow gap is combined together, so there are two kinds of gap structures on the radiator at the same time. The antenna has a double-sided structure. The bandwidth range of the antenna is 1.7-2.33 GHz and 3.2-3.9 GHz, the bandwidth of the two frequency bands is 630 MHz and 700 MHz respectively, which can be used for DCS(1 710-1 880 MHz), PCS(1 850-1 990 MHz), UMTS(1 920-2 170 MHz) and WIMAX (3.3-3.6 GHz) in the mobile communication. The maximum gain of the antenna is 3.6 dB in the low frequency band, 5.1 dB in the high frequency band, and the isolation is below -20 dB, which conforms to the design requirements of the MIMO antenna.