Abstract
Abstract
This article provides a novel technique of generating both RHCP and LHCP waves from a CPW fed MIMO antenna over a wide frequency range 24.6–28.2 GHz by integrating it with a metasurface. The metasurface is designed as a broadband reflective cross-polarization converter working from 23–32.6 GHz. The metasurface is placed 1 mm below the MIMO antenna constituting orthogonally placed antenna elements. The impinging electromagnetic waves from the linearly polarized antenna are converted into circularly polarized waves when they get reflected from the metasurface and interfere with the radiated waves from the antenna. In order to decipher the underlying modal behaviours of the metasurface, characteristic mode analysis is utilized. Due to orthogonal orientation of the antennas, oppositely placed antennas exhibit the same type of polarization conversion while adjacently placed antennas exhibit opposite type of polarization conversion. This results in generation of both RHCP and LHCP waves from different elements of the MIMO antenna using the same metasurface at 5 G frequencies registering an axial ratio bandwidth (ARBW) of 15.3%. With a diversity gain (DG) of better than 9.96 and an envelope correlation coefficient (CC) of less than 0.015, the proposed CP antenna exhibits strong MIMO performance. Prototypes of the antenna and the metasurface have been fabricated and measured for validating the simulated results.