A simple design to compute accurate resonant frequencies of circular microstrip antennas using artificial neural networks. (ANN) is proposed. ANN model is developed to calculate the antenna dimensions for the given resonant frequency, dielectric constant and height of substrate. ANN is designed using radial basis function networks. The results show better agreement with the trained and tested data of ANN models. The results are verified by the experimental results to produce accurate ANN models. This presents ANN model practically as an alternative method to the detailed electromagnetic design of circular microstrip antenna. We have also used a simulator to validate the present model.