Dynamic Analysis of Thin Film Multiferroic Radiation via FDTD Methods
A bulk acoustic wave (BAW) based multiferroic antenna structure is proposed, to overcome the platform effect associated with low-profile antennas. Numerical analysis based on the one-dimensional finite-difference time-domain (1D FDTD) technique, as well as analytical analysis is applied. The dynamic stress profile within the resonator and the radiation quality factors (Q factors) are simulated. The radiation of the electromagnetic waves acting as a damping load to the acoustic resonances is represented. In addition, both electrical conductive loss of nickel and magnetic damping loss of yttrium iron garnet (YIG) are considered and simulated with full dynamics via the coupling of Maxwell's equations and Landau-Lifshitz-Gilbert (LLG) equations. In the LLG/Maxwell modeling, the simulated relative permeability curves match the theoretical plot obtained by classical analysis. Furthermore, the radiated power is simulated, which increases as the thickness of the film increases or the line width of the material decreases. It should be noted that the normalized radiation power is maximum at the ferromagnetic resonance frequency (FMR), which opens up a new antenna design strategy to make the antenna work at FMR to enhance the radiation. The agreement between the numerical solutions and the analytical solutions provides a validation to the operating principle of the proposed antenna.