Dual-band microstrip filter based on near-zero propagation

In this paper we present a new class of dual-band filters based on near-zero propagation - a new paradigm emerging from recent developments of metamaterials. By using two different metamaterial unit cells and by properly coupling them to a microstrip host, permittivity- and permeability-near-zero propagation is achieved at two different frequencies, thus allowing the design of dual-band filters with arbitrary positioned passbands. At the same time, due to specific properties of NZ propagation, such filters will exhibit low insertion loss and good selectivity, as well as a reduced variation of group delay in comparison to the conventional solutions.