Diple antenna & FDTD

I am trying to simulate a dipole antenna operating at 900MHz in free space by using FDTD method (sinusoidal excitation), but I have some probelm because the obtained results of electric field intensity arround the dipole are the high order(E+37 . Can anyone help me to resolve this problem.
Thank you.

hi,

may be you didn't make a check for the maximum stable time step, in such cases the solver becomes unstable and gives very high and nonphysical results.