Abstract: The aliase-free field of view directly determines the field of view range that can be observed by the aperture synthesis, which is of great significance for improving the quality of brightness temperature images of mirrored aperture synthesis within the observation field. Therefore, based on the discrete cosine transform (DCT) domain convolution theorem, this article derives the array factor of the mirrored aperture synthesis and obtains that the aliase-free field of view of the mirrored aperture synthesis is half of that of the aperture synthesis. In addition, the reconstructed brightness temperature image of the mirrored aperture synthesis can be represented as the product of the extended scene and the extended array factor. Then, the theoretical correctness of the aliase-free field of view for one-dimensional and two-dimensional mirrored aperture synthesis is verified using the simulations and existing mirrored aperture synthesis experimental systems. The research method in this paper can provide reference for improving the quality of brightness temperature images for mirrored aperture synthesis.