Stripline filter device having a coupling dielectric layer between two stripline resonators

A stripline filter device comprising at least two dielectric substrate assemblies stacked to each other, each dielectric substrate assembly including:

• a pair of superimposed dielectric substrates, the substrates being superimposed at facing surfaces thereof and each substrate also including outer surfaces different from the associated facing surface,
• at least one stripline resonator of a predetermined pattern interposed between the facing surfaces of the paired substrates,
• a ground conductor provided at least on the outer surfaces of each dielectric substrate, and
• an intermediate dielectric layer having a dielectric constant smaller than that of each of the dielectric substrates, the intermediate dielectric layer being interposed between the dielectric substrate assemblies for adjusting a coupling quantity between the stripline resonators in the stacked dielectric substrate assemblies.