Wideband Isolation and Gain Enhancement of Sub-6 GHz MIMO Antenna Using an Asymmetric Epsilon Negative Metasurface Reflector

In this paper, a plus-shaped epsilon negative metamaterial-based reflector (called as PS-ENG reflector) is proposed for gain and isolation enhancement of MIMO antenna designed using slotted rhombus radiating elements. The PS-ENG reflector is designed on 0.8-mm-thick FR-4 substrate, by placing newly designed epsilon negative unit cells asymmetrically in the form of 1-4-1 array. The performance of the PS-ENG reflector is validated by placing it at a minimized distance of 8 mm (≈λ/8, where λ is operating wavelength at 3.0 GHz) beneath the ground plane of the MIMO antenna. The PS-ENG reflector-loaded MIMO antenna covers a wide range of sub-6 GHz ranging from 3.3 to 6.0 GHz and exhibits enhanced MIMO performance metrics such as high isolation, high gain (improved gain by 3.2 dB (1.18–4.38 dB), low envelope correlation coefficient (ECC < 0.02), and high diversity gain (DG = 9.999 dB) over a wide bandwidth of 2700 MHz. Thus, the proposed antenna is perfect fit for various sub-6 GHz, IOT applications.