Abstract: Future radio systems，such as software defined radio and cognitive radio have posed a significant challenge to antenna design，particularly reconfigurable antenna design.The paper presents a simulation method of the reconfigurable antennas，in which the fullwave simulation is adopted for the unloaded array，while network analysis is used along with genetic algorithm to search for network characteristics and radiation patterns of arbitrary loading arrays.Using this method，a square ring reconfigurable antenna is simulated to find the reconfigurablity of frequency and radiation patterns.The simulation result shows that the reconfigurable antenna concerned in the paper has frequency reconfigurablity and pattern reconfigurablity，making it a promising application in the future cognitive radio and smart antennas.