Planar microwave lens based on complementary metamaterials

With the developement of metamaterials in recent years, more and more interests have been attracted in the potential applications of these novel materials. Metamaterials are usually composed of periodic subwavelength units, which can produce electric or magnetic responses under the excitation of external incident waves. Since the characteristic dimensions of the composing units are far smaller than the working wavelength, effective medium theory can be utilized to describe the electromagnetic properties of the periodic structures. A number of applications have been verified by experiments like invisible cloaks, microwave lens and tunneling structures [1–3].