US Patent 7561011 Dielectric device

A dielectric device includes a dielectric substrate and a resonator unit. The resonator unit includes first and second holes. The first hole opens on a first surface of the dielectric substrate and extends toward a second surface opposite to the first surface. A first internal conductor is provided inside the first hole. The second hole opens on a third surface of the dielectric substrate, extends toward a fourth surface opposite to the third surface, and is connected to the first hole. A second internal conductor is provided inside the second hole with one end connected to an external conductor film on the third surface and the other end connected to the first internal conductor. The first hole has a recess opposed to a junction with the second hole. The first internal conductor in the recess is opposed to the external conductor film on the fourth surface across the dielectric substrate.