The invention provides a dielectric substrate; a ground conductor pattern is formed on one surface of the dielectric substrate and which has a ground conductor pattern omission portion; a strip conductor pattern formed on a surface of the dielectric substrate opposite to the surface having the ground conductor pattern; a conductor pattern for shorting of a waveguide formed so as to be continuously connected to the strip conductor pattern; connecting conductors for connecting the ground conductor pattern and the conductor pattern to each other within the dielectric substrate; and a waveguide connected to the dielectric substrate so as to correspond to the ground conductor pattern omission portion. Also, a microstrip line is constituted by the strip conductor pattern, the ground conductor pattern, and the dielectric substrate. Further, a dielectric waveguide shorting portion is constituted by the conductor pattern, the ground conductor pattern, and the connecting conductors.