Abstract: Time Reversal (TR) is a new method for wave propagation and control with electromagnetic environment adaptability. Time reversal method can simplify the pattern design of antenna arrays with complicated structures. In this paper, a time reversal method is investigated for determining the excitation of a micro-strip antenna array. Both simulations and experiments are performed. The results show that the time reversal method can exactly determine the array excitation for beam patterns with different desired main-lobes. Compared with the traditional array excitation-determining methods, time reversal has remarkable advantages in determining the array excitation since it does not require coupling compensation computation and has no limitations to the element geometrical structures and array configurations.