The 4-Port multiband operated MIMO antenna operating at 4GHz, 6GHz and 9GHz is proposed to target the 5G and P2P communication applications. The electrical size of the 4-Port antenna structure is 0.8λ x 0.48λ. The unique shape of a single radiating patch element is identified by engraving a circular shape patch element and modifying the shape of the feedline. The optimisation in terms of return loss was achieved based on the defected ground structure and changing radius of different elements of the patch structure. The 2-Port and 4-Port MIMO antenna structures are designed using the FR4 substrate and their return loss is compared and examined. The proposed design provides a minimum return loss of -22dB, peak bandwidth of 2.25GHz, peak gain of 4.67dB, and normalised directivity of 1870. Different MIMO diversity parameters are analysed. The proposed design provides an envelope correlation coefficient of 0.01, Diversity gain near 10dB, mean effective gain of almost zero, channel capacity loss of almost zero and Mean effective gain within the acceptable range. The overall Performance of the Proposed Design is compared with other 4-Port design structures and it represents healthy gain, multiple band response and proper diversity parameters making it suitable for the 5G and P2P communication applications.