Ultra-wideband MIMO antenna with reconfigurable band notch characteristics and improved isolation

This paper introduces an ultra-wideband (UWB) dual-element MIMO antenna with reconfigurable band-notched characteristics. The antenna comprises a partial elliptical radiator patch with a partial trapezoidal notched ground and has a fractional bandwidth of 120%. By incorporating two inverted U-shaped slots and three PIN diodes, the antenna can switch between dual, single, and no notches, enabling reconfigurable band notches for WIMAX (3.5 GHz), sub6 5G band (4.5 GHz), and satellite communication band (7.5 GHz). The proposed structure has been extended to a two-element MIMO in a side-by-side arrangement, achieving isolation characteristics below -30 dB over the bandwidth by incorporating stubs between the antenna elements. The MIMO antenna has acceptable diversity performances, and the switching characteristics remain unperturbed. The time-domain behavior shows that the structure can handle impulse signals. The overall substrate dimension of the dual-element MIMO is 1.4λ0×0.7λ0. The simulated and measured results are in good agreement.