We firmly think that it is proven that most of the ideas, results, and discussions presented in C. Huang, C. L. Du, and X. G. Luo, Appl. Phys. Lett. 91, 143512, 2007 were already present in our previous paper (M. Beruete, I. Campillo, J. S. Dolado, J. E. Rodríguez-Seco, E. Perea, F. Falcone, and M. Sorolla, IEEE Trans. Antennas Propag. 54, 340, 2006) and that the antenna design in Huang et al. cannot be considered original at all since it is identical to our design. The only innovative aspect in Huang et al. is the discussion about the multiple slit source.
