Directional Antennas for Sub-THz and THz MIMO Systems: Bridging the Gap Between Theory and Implementation

Multiple-Input Multiple-Output (MIMO) systems have been proposed to increase the capacity and transmission distance of sub-THz and THz communication systems. Although much work has been done to pave the way for arrays and arrays of subarrays using omnidirectional or semi-omnidirectional antenna elements, few works explore the benefits of directional antenna elements in (sub-)THz MIMO systems. This work presents a brief survey of what has been done for sub-THz and THz multiple antenna systems and builds on the previous work to suggest using more directional antenna elements in sub-THz and THz MIMO systems. The first experimental implementation of a sub-THz diversity scheme is also used to verify the findings. Both the numerical and experimental analyses demonstrate that directional antenna elements in sub-THz and THz MIMO can increase the achievable data rates due to their focusing power and the shape of their radiation pattern.