Dual-Band Closed-Slot MIMO Antenna for Terminal Wireless Applications

This article presents a dual-band closed-slot multiple-input multiple-output (MIMO) antenna for terminal wireless applications. By simply inserting additional slots between the closely spaced parallel-arranged radiation slots, the signal impedances of common mode (CM) and differential mode (DM) can achieve similar status, and the strong mutual coupling effect is then eliminated. The proposed slot antenna pair shows good isolation of better than 20 dB across the desired Wi-Fi bands. In addition to the one-wavelength slot antenna, flexible extension to a more compact half-wavelength slot pair is given for future industrial design (ID), which provides further validation of the method. We fabricate the
$4\times4$
MIMO antenna system constituted by two sets of one-wavelength closed-slot pairs. The experimental results show that the proposed MIMO antenna can offer isolation of better than 18 dB, an envelope correlation coefficient (ECC) of lower than 0.1 between all ports, and a wide −3 dB efficiency bandwidths across the desired bands. The results confirm that the proposed antenna is a viable candidate for Wi-Fi communications inside routers.