Characteristics of Electrically Small Spiral Resonator Metamaterial With Electric and Magnetic Responses

In this letter, we investigate the design, fabrication, and measurement of square spiral resonator (SR) metamaterial. The simulation, experiment, and the parameter retrieval results all validate that the one-arm SR only has a magnetic response, while multiarm (including two-arm, three-arm and four-arm) SR have a magnetic and an electric response in two different frequency regions, respectively. Moreover, compared to some previous traditional designs of metamaterial with double responses, SR have the advantages of small electrical dimension and exhibit different electric/magnetic responses corresponding to different number of arms under a fixed unit length. Theoretical analysis corresponds very well with experimental results.