Characteristic modes (CMs) provide deep insight into the electromagnetic behaviour of any arbitrary shaped conducting structure because they are unique to the geometry of the object. In this paper, we propose a novel approach using the theory of CMs to analyse metamaterials and provide physical insight of their synthesis applications. It is shown that the magnetic response of a split-ring resonator when a magnetic field is perpendicular to the ring, can be achieved with a reactive impedance substrate when the magnetic field is parallel to the substrate. Application of this analogy is reported by explaining the performance improvements for patch antennas achieved by some researchers. The proposed approach prove to be useful for analysing metamaterial inclusions when associated to radiating elements.
