An encapsulating meta-molecule: U resonator containing spiral line

A new kind of planar metamaterial is investigated. It consists of meta-molecules where a first resonator encapsulates a second resonator. The near-field coupling between these resonators is the dominating effect determining the characteristics of the material and is discussed in detail at a physical level. The technique of encapsulating allows both to miniaturize the unit cell, which is advantageous with respect to making the material homogeneous, and to invoke strong coupling, which is advantageous for tuning the material.