PURPOSE: To prevent generation of unnecessary waveguide mode based on camber of an end face of a metallic plate by providing a fixed screw to the end face of the carrier metallic plate on which an integrated circuit substrate is mounted so as to fix the end face of the metallic plate and the bottom of a device case.

CONSTITUTION: Two microwave/millimeter wave integrated circuits 2a, 2b are arranged on the device case 11a and microstrip patterns 5a, 5b of both the circuits are connected by a connecting ribbon 8. In such arrangement, stud screws 14a, 14b are provided to carriers 13a, 13b of both the integrated circuits. Both ends of the carriers 13a, 13b are fixed adheredly to the fitting face of the device case 11a by using the stud screws. Since the change in a carrier gap 16 due to the camber of the end of the carriers 13a, 13b is prevented by using the method above, generation of unnecessary waveguide mode due to disturbed matching of the end face is prevented.