Graphene-based frequency agile isolation enhancement mechanism for MIMO antenna in terahertz regime

This paper presents a graphene-based frequency tunable isolation enhancement mechanism for terahertz (THz) MIMO antenna. The presented simple and compact decoupling method could also be employed for any THz device. An isolation enhancement of about 30.41 dB has been achieved at the frequency of operation. The decoupling structure has the ability to suppress mutual coupling caused by any radiation mode of the MIMO element. The change of 0.2 eV (i.e., from 0.5 to 0.7 eV) in chemical potential (${\mu }_c$) provides a frequency tunability of about one THz in the transmission coefficient of the decoupling structure. The proposed decoupling technique is applied to the slot ring-based dual-polarized MIMO/diversity antenna. The diversity antenna provides a bandwidth (BW) of 0.83 THz (5.68–6.51 THz) with isolation of 47.56 dB at resonant frequency (6 THz). The gain and efficiency of the proposed diversity antenna at 6 THz are better than 3.99 dBi and 90.17%, respectively. The envelope correlation coefficient (ECC) calculated from far-field and diversity gain (DG) are 4.818 × 10 ${}^{-7}$ and 10, respectively. Total active reflection coefficient (TARC) is found to be less than -10 dB for different values of input feeding phase $\theta$ and the mean effective gain ratio (${\text{MEG}}_i$/${\text{MEG}}_j$) is close to one, which confirms the antenna’s applicability for diversity application in multipath rich wireless channels.