A Decoupling Method for Antennas With Different Frequencies in 5G Massive MIMO Application

A method to weaken the interference of antennas working in different frequencies is proposed in this paper. It uses a Frequency Selective Surface (FSS) placed between two different antennas. For one antenna, the FSS acts as an electromagnetically transparent structure, so the electromagnetic wave will penetrate the FSS and radiates into the free space. For the other one, the FSS acts as an artificial magnetic conductor, reflecting the incoming energy. With this design, two adjacent antennas could keep their individual performance especially radiation patterns normal. It is worth noting that although the FSS has been used in many aspects, such as reducing antenna's radar cross section or reducing the coupling between the identical antennas, its application in the field of `different antennas decoupling' is the first time. An embodiment is displayed in this paper for verification. Two antennas worked at different bands of 5G are placed very close with an FSS structure inserted. It turns out that the whole antenna has good electrical and radiation properties over the working band. This decoupling strategy can be very useful in 5G Massive MIMO application.