Compact UWB-MIMO antenna with metamaterial FSS decoupling structure

In this paper, an UWB-MIMO antenna with frequency selective surface (FSS) decoupling structure is proposed. To realize antenna system miniaturization and integration, silicon material is applied as substrate. The proposed antenna becomes a very compact construction with dimension of 38.2 × 26.6 × 0.4 mm. The proposed broadband FSS unit consists of four split rectangles and one I-shaped strip. The effective permittivity or effective permeability of FSS unit is negative, so the FSS is a metamaterial structure and has a broadband frequency band gap in the entire UWB range. Six FSS units are positioned in the middle of antenna backside, like band-stop filter to reduce the coupling between the antennas placed side-by-side. Compared to UWB-MIMO antenna without FSS, the proposed array not only keeps each antenna performance but also decreases 7.2 dB coupling. The UWB-MIMO with FSS structure provides an overall isolation of more than 16 dB in the UWB spectrum, so it is suitable for portable UWB-MIMO system applications.