In this paper, an SMMW interferometric radiometer concept is demonstrated by a two-element interferometer with dedicated high accuracy SMMW devices. Point-source calibration method is introduced in order to reduce instrument errors. Interference fringes and point target images are presented by this SMMW interferometer. The linear phase error of the interference fringes is less than 2° and the angular resolution is better than 0.57°. The measured performance characteristics of the two-element interferometer are consistent with the theoretical analysis. This interferometer demonstrates a new method for passive SMMW remote sensing.