The numerical analysis of highly iterated Sierpinskimicrostrip patch antennas by method of moments (MoM) involvesmany tiny subdomain basis functions, resulting in a very largenumber of unknowns. The Sierpinski pre-fractal can be definedby an iterated function system (IFS). As a consequence, thegeometry has a multilevel structure with many equal subdomains.This property, together with a multilevel matrix decompositionalgorithm (MLMDA) implementation in which the MLMDAblocks are equal to the IFS generating shape, is used to reduce thecomputational cost of the frequency analysis of a Sierpinski basedstructure.