AbstractResonant frequencies of shielded rectangular and circular microstrip patches have been determined using the modified Wolff model (MWM). The model determines effect of top‐shield, side‐walls, and end‐walls on the resonant frequency. Results of the MWM have been compared to those of SDA and FEM. The MWM has an accuracy of 0.2% compared with experimental results. Numerically, the MWM is fast even on a desktop computer. The model is suitable for CAD applications. © 1995 John Wiley&Son