In synthetic aperture terahertz time domain spectroscopy (THz-TDS) imaging, the image of closely spaced targets is degraded due to the high correlation between the waves reflected from the targets. As a method to reduce the correlation, the authors have proposed a position estimation method that applies spatial averaging and MUSIC algorithm to virtually generated array antennas. In this paper, we report the accuracy of DOA estimation based on the position of virtual array. Furthermore, in order to show the effectiveness of the proposed method, we compare it with the conventional BF and MUSIC.