Design of MIMO Antenna Isolation Structure by Material Distribution Method Optimization

Material distribution method, which is a topology optimization algorithm, is used to design the isolation structure in a MIMO antenna. This topology optimization algorithm has the advantage of high topology optimization ability. It is utilized to optimize the impedance matching, port-to-port isolation and polarization of the MIMO antenna. The optimized antenna is verified by HFSS simulation. At the anticipated operation frequency of 5.8 GHz, the return loss is -25 dB, and the mutual coupling between the two ports is -30 dB. That means, in the case of center-to-center distance of $\pmb{\sim 0.39}\ \lambda_{0}$, a reduction of more than 17 dB in mutual coupling is achieved. Besides, the relative cross-polarization ratio is 18 dB. We can see this method can be applied in the optimization of MIMO antennas.