The nature of radiation from leaky waves on single- and double-negative metamaterial grounded slabs

In this work we investigate the dispersion and radiation properties of leaky waves on metamaterial grounded slabs. A simple analysis of the dispersion equation of TE and TM waves supported by such structures reveals that leaky waves of only the proper type exist when double-negative metamaterials are employed, while proper or improper leaky waves exist in single-negative grounded slabs, depending both on which constitutive parameter is negative and on TE or TM polarization. Numerical results on specific structures are provided that illustrate the backward nature of radiation from the proper leaky waves and show the behaviour of the frequency scan through broadside as the metamaterial layer changes its constitutive parameters.