A one dimensional finite-difference time-domain (1D FDTD) method is proposed to analyze the performance of a planar strain-mediated multiferroic antenna. The FDTD code simulates the interaction between electromagnetic radiations and acoustic waves through piezoelectricity and magnetostriction by modeling electrodynamics, ferromagnetic dynamics and dynamic mechanics in a cross-coupled fashion. The radiation efficiency of the antenna is plotted, as well as the mechanical-magnetic figure of merit. The interactions between the bulk acoustic resonance (BAWR) and the ferromagnetic resonance (FMR) are observed in the frequency domain. It is concluded that the interactions between the FMR and BAWR can be optimized to obtain enhanced radiation efficiency or to broaden the bandwidth.