Broadband negative refraction at microwaves with a multilayered mushroom-type metamaterial

In this paper, a multilayered mushroom-type structure is proposed as a bulk metamaterial, which creates a broadband negative refraction. The metamaterial is modeled using homogenization methods as a multilayered structure formed by a uniaxial wire medium loaded with periodic metallic elements (for example, patch arrays). It is shown that the phase of transmission coefficient decreases with the increasing incidence angle, resulting in the negative spatial shift of the transmitted wave. The homogenization model results are obtained with the uniform plane-wave incidence, and the full-wave CST results are generated with a Gaussian beam excitation, showing a strong negative refraction in a wide frequency band.