A novel optimization algorithm, namely the Tree Growth Competition Algorithm (TGCA), is for the first time to be employed for antenna design. The TGCA considers the growth of a tree as a unity of opposite procedures of growing and wilting, and simulates the tree's growth by defining the sunlight adaptability, nutrition factor and shade factor as well as performing the burgeoning, growing and wilting mechanisms. In this paper, a microstrip tree antenna is designed by using the TGCA in conjunction with the full-wave EM simulation based on the Finite-Difference Time-Domain (FDTD) for a wide impedance bandwidth. A design result is presented. A prototype of the designed antenna has been fabricated and tested. Good agreement is obtained between the simulated and measured results, and results show the microstrip tree antenna obtains a wide S 11 < −10 dB impedance bandwidth of surpassing 56.7% (from 2.525 GHz to 4.525 GHz).