Bulk Acoustic Wave-Mediated Multiferroic Antennas: Architecture and Performance Bound

Time-varying magnetic flux can be induced from the dynamic mechanical strain of acoustic waves in multiferroic devices that are comprised of piezoelectric and magnetostrictive material. Such devices can be used to create electromagnetic radiation and to alleviate the platform effect associated with low-profile conformal antennas. In this paper, a bulk acoustic wave (BAW)-mediated multiferroic antenna structure is proposed. Its potential for efficient radiation of electromagnetic waves is evaluated by analytically deriving the lower bound of its radiation quality factor (Q factor). A one-dimensional (1-D) multiscale finite-difference time-domain (FDTD) technique is developed to predict the bilateral, dynamic coupling between the acoustic waves and electromagnetic waves. The simulation shows a decaying stress profile in the BAW resonator structure, which implies that the radiation of the electromagnetic waves acts as a damping load to the acoustic resonance. The simulated radiation Q factor matches well with the analytical derivations and the agreement validates both the operating principle of the proposed antenna and the FDTD algorithm developed. The study concludes that efficient antennas may be realized at GHz frequencies with thin film multiferroic material that has thicknesses of the order of 10^-5 wavelength.