Design and Theory of Characteristic Mode Analysis (TCMA) of 4 × 4 high isolation MIMO antenna for sub-6GHz 5G communications

This present work investigates a compact 4 × 4 cup-shaped Multi-Input Multi-Output (MIMO) antenna using Characteristic Mode Analysis (CMA). The systematic design procedure with six characteristic modes allows the antenna to operate at the working frequency of 3.5 GHz. Physical insight into one-element and four-element radiating structures is gained by analysing modal significance, modal fields, and surface currents. The 4 × 4 MIMO structure works in a narrow frequency band of 2.8 to 4.6 GHz. The total size of the MIMO model is 53 × 53 × 1.6 mm3 and is printed on an inexpensive flame-retardant substrate . The plus-shaped decoupling network and the orientation of the radiating patch provide a strong isolation of more than 20 dB across the operating band. The diversity MIMO performance the antenna provides good results with ECC < 0.000005, DG > 9.9999 dB, TARC < − 10 dB, CCL < 0.02b/s/Hz, and MEG ≅ − 3.0 dB. These antenna features make the MIMO design suitable for sub-6 GHz 5G communications.