AbstractThe perfect‐electric‐conductor (PEC) condition implementation for the alternating‐direction‐implicit finite‐difference time‐domain (ADI‐FDTD) method is discussed in this article. By comparing different implementation strategies, it shows that the most accurate implementation method is that the PEC condition is directly incorporated within the tridiagonal matrix. Compared with the other two methods commonly used in conventional FDTD, this method is unconditionally stable and has higher accuracy. The theory proposed in this article is validated through numerical examples. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 526–530, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22185