This paper presents the design an study of a DSRC/sub-6 GHz Koch fractal antenna single, two and four elements integrated with metamaterial structures, are proposed for the C-V2X and IEEE 802.11p/V2X. The design of automotive antenna is a challenging task due to the degradation of the MIMO antenna performance because of mutual coupling and cause spectral regrowth. Initially, a single antenna exhibits very good performance at 5.9 GHz. Subsequently, two elements and four MIMO elements were designed and analyzed which are placed orthogonally at the corner of the substrate introducing a diversity polarization. Meanwhile, to overcome the mutual coupling effects and improve the isolation between the radiating elements, two new different shaped left-handed metamaterials based on broadside and electrically coupled square split-ring resonator (SRR) with negative permeability and negative permittivity are suggested and their reflection properties are analyzed. However, the performances of various MIMO antenna configurations are investigated before and after inserting the metamaterial structures to assess the potential enhancements achieved. Finally, a further investigation concentrates on the effects of these metamaterial structures on the MIMO antenna radiation pattern and surface current density. In summary, the study demonstrated through simulations and measurements that the suggested MIMO antenna configurations, with the integration of metamaterial structures, exhibit improved performance, achieving a mutual coupling of -45 dB and demonstrating good MIMO diversity attributes.

A new miniaturized wideband self-isolated two-port MIMO antenna for 5G millimeter-wave applications