any antenna using 3D-FDTD method

hello everybody..............
i want to solve the antenna parameters like return loss curve , input impedance and far field of probe feed rectangular DRA and i am unable to solve so plz help me .............
plz send me fully calculation of any antenna using 3D-FDTD method....i want to see how can i proceed ?
provide me algorithm step by step to solve my problem........................
i need it for example to solve my problem..................

i'm also looking for that-----if u get that please RAVi-send me