UCLA

The goal of this dissertation is to propose, elaborate, and validate a modeling, simulation and design tool for magnetic RF devices that encompasses the fields of electrodynamics, micromagnetics and other possible physics such as elastodynamics. Comparing to conventional approach based on magnetostatic approximations, our solution with full dynamics can provide a correct prediction to the electromagnetic power flow which determine the impedance match and radiation efficiency of a thin film magnetic filter or antenna.

First, we introduce both one-dimensional (1-D) and three-dimensional (3-D) modeling frameworks, with the former serving as the proof of the concept and the latter as a comprehensive modeling tool. The 1-D algorithm is based on an unknown reduction strategy to overcome the multiscale problem. The 3-D modeling is based on modified alternating-direction-implicit finite-difference time-domain methods (ADI FDTD) with unconditional stability. It has the capability of modeling the anisotropic and dispersive properties of magnetic material. The proposed algorithms solve Maxwell’s equations and Landau-Lifshitz-Gilbert (LLG) equation jointly and simultaneously, with verified accuracy and efficiency.

Second, we propose a novel antenna radiation mechanism, bulk-acoustic-wave (BAW) mediated multiferroic antenna. Such multiferroic antennas compose of piezoelectric material and magnetostrictive material, in which time-varying magnetic flux can be induced from the dynamic mechanical strain of acoustic waves. The BAW mediated multiferroic antenna can be used to create electromagnetic radiation and to alleviate the platform effect associated with low-profile conformal antennas. Its potential for efficient radiation of electromagnetic waves is evaluated by analytically deriving the lower bound of its radiation quality factor (Q factor). Moreover, the performance of the antenna is predicted by both the 1-D and 3-D modeling tools that we have developed. The study concludes that efficient antennas may be realized at GHz frequencies with thin film multiferroic material that has dimensions on the order of 10-5 wavelength.

Finally, we summarize the research results and discuss future potential research opportunities and challenges in this field. There are still many unresolved questions in this new research field. Nevertheless, the multiphysics time-domain solver that we proposed has shown the potential of an unprecedented ability to accurately model and design next-generation magnetic RF systems and components.