Microstrip antennas are one of the most popular antenna types, since they are lightweight, have simple geometries and are inexpensive to fabricate. In a circular microstrip antenna designing, it is important to determine the resonant frequency of the antenna accurately because the antenna has narrow bandwidth and can only operate in the vicinity of the resonant frequency. So, a theory to determine the resonant frequency is helpful in antenna design.Neural Network Model (NNM) is an emerging field of mathematical analysis which has acquired major role in recent times as a powerful tool for numerical solutions to problems. It consumes less computation time.In this book, Neural Network Model has been developed for the calculation of the resonant frequency of a circular microstrip antenna.The results from the developed model have been compared with the results from the model derived from Genetic Algorithm and also with the theoretical and experimental results reported by other scientists. The results from the developed neural network model are in close agreement with the results reported by other scientists.