This letter presents an unconditionally stable locally one-dimensional (LOD) finite-difference tune-domain method based on the simplified sampling biorthogonal algorithm (SSB-LOD). The suggested approach requires fewer arithmetic operations than in the SSB-ADI scheme. This leads to a reduction of CPU time relative to the SSB-ADI method while equivalent numerical accuracy is retained. The numerical implementation of two parallel conducting plate shows that the CPU time of the SSB-LOD has been reduced to approximately 85% of that of the SSB-ADI. (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2183-2185, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25461