AbstractThe computation of impedance matrix for layered structures is time‐consuming because each element requires the evaluation of quadruple integrals. To increase the efficiency, we propose a technique referred to as the fast matrix generation. In this method, conventional and rigorous numerical methods are still used for generating the impedance matrix elements that are associated with the near‐field interactions, whereas a more efficient scheme is employed where the separation distance between basis and testing functions exceeds a threshold value. A significant saving in computation time, sometimes over 90%, can be achieved via the application of this approach, as is demonstrated by numerical results for a number of typical microwave circuits. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 204–213, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24015