Parallel plate mode suppression in LTCC-integrated stripline circuits using periodic bandgap structures

This paper presents a way to enable extended passive structures in stripline technology by means of controlling the parallel plate modes in the desired frequency band of operation. This is achieved by periodic structures of the Sievenpiper type. They enable microstrip-to-stripline transitions that were previously very difficult to realize at very high frequencies. Simulated and measured data is given to verify the feasibility of circuitry designed in this proposed kind of stripline environment and in particular in LTCC technology. It turns out that this concept enables submerged RF structures and circuits up to 120 GHz and possibly above while avoiding many disadvantages and side effects observed in previous approaches.