Article ID: 13.20160281
The Γ-point group velocity, vgΓ, of lossy Dirac cone composite right/left-handed (CRLH) metamaterials is derived theoretically for the first time based on the equivalent circuit analysis. With the balanced CRLH condition, it is theoretically shown that vgΓ takes the maximum value of a half of the speed of light in the background medium under the condition where the quality factors of the resonators in the series and shunt branches in the unit cell, Qse and Qsh, are equal, whereas under the condition of Qse ≠ Qsh, vgΓ becomes smaller with the slow wave factor of κ = (k1/2 + k−1/2)−1 where k is the quality factor ratio k = Qsh/Qse.