We present a reconfigurable one dimensional leaky wave antenna (LWA) in the terahertz region. The proposed LWA can steer its beam at a fixed operational frequency using liquid crystals (LC). It consists of a rectangular waveguide filled with three layers of dielectric: an LC layer sandwiched between two spacers. The dominant TE 10 mode leaks into the free space through a partially reflecting surface (PRS). Using numerical analysis, we optimized the PRS reactance for maximum gain and beam steering angle and confirmed the results by full-wave simulation.