MIMO Antenna with Decoupled Antenna Pairs for 5G Mobile Terminals

A high-isolation 8-antenna multi-input multioutput (MIMO) array with decoupled antenna pairs operating in the 3.45 GHz band (3.3-3.6 GHz) for smartphones is proposed. Here, novel capacitive-coupled loop antenna element working at one-wavelength mode is employed to form the MIMO array. Most importantly, the radiating element of the proposed antenna also acts as the decoupling element. By comparing with the normally half-wavelength fundamental mode loop antenna, the proposed one-wavelength mode antenna can greatly reduce the coupled current to adjacent elements. High isolation of better than 15 dB for the 8-antenna MIMO system is achieved without using any additional decoupling elements or decoupling techniques. The total efficiency of higher than 50% and envelope correlation coefficient (ECC) of lower than 0.1 were achieved in the desired operation band.