Miniaturized microstrip and CPW filters using coupled metamaterial resonators

In this paper, it is shown that the application of metamaterial resonators to the design of planar microwave filters provides a high level of miniaturization for such devices. Specifically, split-ring resonator, complementary split-ring resonator, and spiral resonator are used to synthesize microwave filters using the coupling coefficient approach. Some considerations in order to improve and control the coupling coefficients between resonators are exposed. The magnetic and electric character of the coupling coefficient is analyzed in detail, and a method to identify this coupling is proposed. Finally, several prototype device filters operative at S-band are provided to illustrate the proposed techniques.