High isolation UWB-MIMO antenna with notch characteristics

In view of the problems of multiple narrowband signal interference and strong coupling between antenna units in today’s ultra-wideband systems, a high-isolation ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with notch characteristics is proposed. The antenna consists of two radiating elements, with an overall size of $29 \mathrm{~mm} \times 40 \mathrm{~mm} \times 1.6 \mathrm{~mm}$. The grounding plate introduces I-shaped fence branches to achieve higher isolation. By etching “U”-shaped grooves on the radiation patch and introducing “ U “-shaped branches on the right side of the feeder, the double notch characteristics are achieved, effectively suppressing interference in the two frequency bands of WLAN ($5.15 \sim 5.85 \mathrm{GHz}$) and X-band downlink frequency bands ($7.25 \sim 7.75 \mathrm{GHz}$). The experimental results show that the UWB-MIMO antenna has an operating bandwidth of $2 \sim 12.5 \mathrm{GHz}$, and the two notch bands are $4.91 \sim 5.86 \mathrm{GHz}$ and $6.8 \sim 7.96 \mathrm{GHz}$. In the entire working bandwidth, the isolation degree is greater than 20 dB, the envelope correlation coefficient ECC is less than 0.00375, and the diversity gain DG is greater than 9.99 dB, indicating that the antenna has good characteristics in all aspects and can meet the requirements of UWB-MIMO antennas.