This paper is about deriving expected values for antenna gains in the presence of antenna movement. The focus herein is on the THz band (0.3–10 THz) backhaul and fronthaul links. In the THz band communications, high antenna gains are required and this causes strict constraints on the antenna misalignment. In the backhaul links the motion of the antenna is mainly coming from the building or antenna mast swaying. This is the reference scenario in this paper. Three different movement models are applied: Gaussian motion of a single antenna, Gaussian motion of the both ends of the link, and 2-dimensional Gaussian motion. The expected antenna gains show a degradation of the performance as the movement increases. This is well expected and has an impact on the high directional links where angular tolerances are low. The derived models can be utilized and modified for link budget calculations and stochastic models for various different use cases and scenarios.