AbstractAn interdigitated split‐ring resonator is proposed and obtains negative permittivity (εr), magnetic permeability (μr), and negative refractive index (n) over a narrow frequency band. This article demonstrates that the proposed structure has a linear frequency response the geometry of the structure and small planar resonators for low frequency metamaterials are possible. The experimental results show that the resonators exhibit a negative refractive index at frequencies of a few hundred MHz to a few GHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:174–177, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25683