Book Description

While there is a need for low frequency (30-300 kHz) communication through lossy media like seawater and the human body, these dielectric cluttered environments present challenges to conventional communication devices in the form of signal attenuation. This is due to the interaction of the electric field component of electromagnetic radiation with the conductive portions of the surrounding media. Magnetoelectric antennas provide a solution to this problem in that they primarily output magnetic energy in the near field. Furthermore, by using strain-driven magnetoelectric antennas, antenna miniaturization is realizable by operating at acoustic resonance rather than electromagnetic resonance. While there have been successful experimental demonstrations of low frequency magnetoelectric antennas, the community lacks a systematic approach for antenna design and characterization. This first half of this work presents a decoupled system of models including a method for predicting magnetic moments of bulk samples using Landau-Lifshitz-Gilbert micromagnetic simulations, enabling radiation predictions via an analytical dipole model, resulting in a paradigm shift from dipole radiation validations to dipole radiation predictions. This work includes a methodical testing approach to assess the antenna's performance in terms of signal strength, quality factor, and radiation patterns, determining the antenna to be comparable to state-of-the-art pacemaker antennas. The second half of this work discusses the design and characterization of a Galfenol antenna which resonates at two distinct frequencies. This second antenna, called a dual band magnetoelectric antenna, allows for communication via frequency shift keying (FSK) and is the first magnetoelectric to accomplish FSK at two resonance frequencies. This work demonstrates that the data bandwidth can be increased by an order of magnitude and discusses potential for future improvement in data bandwidth. This dissertation also features a discussion on parasitic effects and mitigation techniques as well as material parametric studies for improved antenna performance. This work presents a comprehensive procedural guide for the design, fabrication, and characterization of low frequency magnetoelectric antennas, effectively bridging a gap in the existing literature.