8-Port Quad-band MIMO Antenna with an Isolation Enhancement Technique for Sub-6 GHz 5G Applications

In this paper, an eight-port quad-band multiple-input-multiple-output (MIMO) antenna system with an isolation enhancement technique is presented. The proposed isolation technique is used to improve the isolation between the ports with higher mutual coupling. This technique can also be repeatedly applied between other ports to improve the isolation without affecting the impedance bandwidth and other transmission coefficients. Each radiating element of the proposed system is excited using an offset-fed coaxial port. The multiple radiating elements are placed in a double-folded symmetry fashion to reduce the number of different parameters in the global S-parameter matrix. The designed quad-band 8-port MIMO antenna system is printed on Rogers RO4350B (ϵ
r
=3.55, tan δ=0.004) substrate with dimensions of 120×70×1.52 mm
³
. The proposed MIMO antenna system’s frequency bands lie in 5G n77, n78, n79, and n46 sub-6 GHz bands. The simulated and measured parameters are in good agreement.