Separation of Coupling Coefficient Between Resonators into Magnetic and Electric Components Toward Its Application to BPF Development

A new concept on resonator's coupling coefficient is applied to various structures. The main idea is to discriminate the magnetic and electric contributions based on the coupled mode theory. Strong to weak coupling of open-ring resonators when they are faced on broadsides, is clarified together with the magnetic coupling's survival at the long distance. Combline and interdigital couplings are well explained to have different coupling property. Some new BPFs are proposed on the basis of the present theory, which could realize significant miniaturization of multi-stage BPFs.