A Four-element Ultra-wideband MIMO Antenna with High Isolation for IOT Applications

In this paper, a four-element MIMO antenna with low mutual coupling is proposed and integrated with the UWB technology for IOT applications. The single element of MIMO antenna consists of an octagonal slot and a flower-shaped structure with coplanar waveguide (CPW)-fed. Each element is arranged orthogonally to form a four-element MIMO antenna. The unique decoupling design is achieved by adding a rectangular slot structure in the center of the four-element MIMO antenna so that a high isolation between elements can be achieved. The overall dimension of the MIMO antenna is 65 × 65 × 1.2 mm
³
, which can be easily printed on the low-cost FR4 copper-clad dielectric substrate. The simulated results from the well-known HFSS show that the presented MIMO antenna can achieve a frequency band of 3.6–8.25 GHz with an isolation of greater than 18 dB over the whole bandwidth. Furthermore, the UWB-MIMO antenna has good radiation characteristics with a peak gain of 4.8 dB, a high radiation efficiency larger than 86%, and a low envelope correlation coefficient smaller than 0.01.