In a letter by Yang (Microwave Opt Technol Lett 50 (2008), 2965–2967), the bandgap characteristic of a new uniplanar compact electromagnetic bandgap is considered. The authors use the dispersion diagram related to the irreducible Brillouin zone (IBZ) to determine the bandgap. We have already noticed the IBZ used by the letter is not correct, according to the symmetry of the structure. So, the resulted bandgap characteristic is not true. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26153