Research discussions and developments in beyond fifth generation (B5G) have been taking place in academic and research groups all over the globe to address the future technology requirements, and propose the usage of higher frequencies such as Terahertz (THz) frequency bands due to the huge demand for ultra-capacity and ultra-high data rates. This research focuses on the design and analysis of a sub-THz based E-shaped microstrip patch antenna at 140 GHz for B5G applications. The antenna and its 4-element array is designed on a high-performance substrate of Rogers RT/duroid 5880. Parameters like radiation pattern, gain and s-parameters have been examined using Method of Moments (MoM) and Finite Difference Time Domain (FDTD) simulations. The designed THz antenna at 140 GHz achieved a realized gain of 8.021 dBi, and the reflection coefficient was around -34.6 dB. NYUSIM channel simulator simulations are also executed for indoor home scenario for wireless applications.