Uses the same high-speed heterodyne detection method sensors as a cell phone. Align the circuits to the printed substrate (b), and place them between the aluminum plate frames ((a) and (c)) into which grooves have been carved and that are in a horn antenna-shape (resembling a bugle). Each sensor is separated by an aluminum plate. Mutual interference does not, in principle, occur. Further, the sensitivity of the microwaves increases by using the horn shape. The horn shape improves the sensitivity of microwaves.