A butterfly-like slot UWB antenna with WLAN band-notch characteristics for MIMO applications

An ultra-wideband (UWB) antenna with butterfly-like coupling slot for 4-element multiple-input multiple-output (MIMO) applications is introduced in this letter. In the design of the UWB antenna unit, the proposed butterfly-like slot is adopted to improve the impedance matching and achieves the operating bandwidth of 3-12 GHz. At the same time, a symmetrical T-shaped meandering strip etched on the ground and connecting with the patch through via produces a notch at 5.1-5.37 GHz, which suppresses the signal interference in WLAN band simultaneously. The results show that the proposed antenna array consisting of four orthogonal elements realized good isolation of lower than -15 dB without any additional decoupled structures. Also, the proposed 2 x 2 MIMO design exhibited good diversity performance in terms of envelop correction coefficient (ECC<0.015), diversity gain (DG>9.92 dB). The gain reaches a maximum value of 6.8 dBi. Simulated and Measured results are in good accordance. All of this reveals the effectiveness of the proposed antenna in MIMO system and it can be suggested as a suitable candidate for UWB applications.