PURPOSE: To miniaturize a beam synthesis circuit, by arranging a beam antenna terminal group and a synthesis signal terminal group in matrix, connecting cross points of the matrix with switches and couplers and controlling the switches and the couplers.

CONSTITUTION: Inputs of beam antennas A1∼A3 and output lines T1∼T3 are arranged in matrix and the input and the output are coupled at each cross point of the matrix via the couplers C1∼C9 and the switches S1∼S9. The degree of coupling is formed as a coarse coupling so as not to change it with the switching of the switches S1∼S9 or the impedance of the switches is made constant. Further, an optional single beam or a synthesized beam is formed by selecting the switching of the switches S1∼S9 and the degree of coupling of the couplers C1∼C9. The beam synthesis circuit is miniaturized and simplified in this way and the degree of freedom of the beam synthesis is improved.