Compact UWB-MIMO Antenna With High Isolation and Triple Band-Notched Characteristics.

A novel and high-performance four-element ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna is proposed in the paper. The proposed antenna is designed by using a novel integration technology of the symmetric layout, orthogonal structure, four-directional staircase-shaped decoupling, and multi-slit and multi-slot techniques. The mutual couplings among the antenna elements are significantly reduced by introducing the symmetric orthogonal and separated four-directional staircase-shaped structure. Furthermore, the antenna size is effectively miniaturized, and its impedance bandwidth is broadened by using a two-sided symmetric layout, partial and defected ground structure, the decoupling structure, and multi-slot and multi-slit techniques. Therefore, the antenna has the low-profile structure and a small dimension of 39mm x 39mm x 1.6mm. Moreover, the proposed antenna achieves triple band-notched characteristics by embedding different type slots and slits on the square radiating elements, default ground structure, and the decoupling structure, respectively. As a result, the antenna obtains the wider bandwidth of 2.30-13.75 GHz with the notched bands of 3.25-3.75 GHz, 5.08-5.90 GHz, and 7.06-7.95 GHz. The three notched bands are good in agreement with the existing interference bands of WiMAX (3.3-3.7 GHz), WLAN (5.15-5.875 GHz), and X-band (7.1-7.9 GHz), respectively. In addition, the proposed antenna also has a lower mutual coupling (< -22dB), lower envelop correlation coefficient (ECC<0.02, except for the three notched bands), high multiplexing efficiency (eta(max) > -3.0dB), stable gain, and quasi-omnidirectional radiation patterns at the entire impedance bandwidth. Therefore, a good tradeoff of the performance is obtained for the proposed antenna. The proposed antenna can be a good candidate for UWB-MIMO wireless communication applications, and especially for portable UWB-MIMO systems.