Coplanar waveguide bandpass filters with separated electric and magnetic couplings

New coplanar waveguide bandpass filters with controllable transmission zeros (TZs) have been developed by using separated electric and magnetic coupling paths. Either magnetic-dominant coupling or electric-dominant coupling generates a TZ, but different positions. Filter TZs are attributed to the electromagnetic couplings, and the additional coupling resonators are not required. The new designs have been demonstrated by an experiment. Advantages of the proposed filters are not only their simple and compact circuit topologies, miniature circuit sizes, but also their controllable TZs without requiring via hole.