In the paper, a very compact UWB-MIMO antenna with four rejected bands property is introduced and investigated. With a T-shape stepped stub on back ground, impedance bandwidth of 3-11 GHz and isolation of -15 dB are achieved. By etching four pairs of symmetrical L-formed slots into the radiators, four bands are isolated. With only a size of 21 mm × 27 mm, the proposed UWB-MIMO antenna system has low port coupling of -15 dB and wide working bandwidth of 3-11 GHz (S11 ≤ -10 dB or VSWR < 2) except 3.5 GHz WiMAX band, 5.3 GHz lower frequency band of WLAN, 5.8 GHz upper frequency band of WLAN and 7.4 GHz X-band. Moreover, other characteristics, such as radiation patterns, antenna gain, antenna efficiency, and ECC (envelope correlation coefficient) are also studied.
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