Characteristics of a double-sided dirac cone metamaterial

We propose a double-sided structure possessing the Dirac cone with non-zero group velocities at the Γ-point in the Brillouin zone for transmission applications. By using an asymmetric single shunt branch to provide a virtual ground, the proposed via-free structure is easy to be fabricated and can be excited by a plane wave. Based on the equivalent circuit theory and full-wave simulations, we design and characterize the unit cell structure with the Γ-point frequency of 28 GHz. To discuss the coupling between the guided modes and a plane wave incident from the far-field, we evaluate the radiation Q-factors at the Γ-point for several structures with various unit cell densities. It has been shown that there exists an optimal value of the unit cell density that minimize the radiation Q-factor.