Metamaterial based circularly polarized four-port MIMO diversity antenna embedded with slow-wave structure for miniaturization and suppression of mutual coupling

Abstract

An engineered metamaterial is proposed for achieving the circular polarization and suppression of mutual coupling in closely placed four-port MIMO (multi-input multi-output) antenna. Data rate and channel capacity (bits/s/Hz) are enhanced four times as all the four ports of the proposed MIMO antenna are radiating and receiving the signals within the same frequency band. Secondly, the recommended antenna doesn’t radiate harmful electromagnetic radiations as it carries low profile characteristics. Design equations are also developed through which antenna could be designed at any desired frequency of interest. Before the analysis of antenna, the unit cell of the metamaterial is analyzed and its double negative characteristics are verified at the resonant frequency. Further, a slow-wave structure is designed and investigated with a microstrip line; subsequently, it is embedded with the proposed antenna structure to refine the characteristics of the antenna. Highly suppressed mutual coupling of the value of −40 dB is achieved between diagonal-ports of the antenna. The proposed antenna offers uncorrelated radiations with satisfactory gain, axial ratio and minimum mutual coupling. The prototype of the proposed structure is manufactured to validate the simulated results with experimental results.