Simultaneous Maximization of Voltage and Power Efficiencies in Magneto-Mechanical Transmitters

Magneto-mechanical resonator arrays (MMRAs) have emerged as a promising transmitter solution for compact ultralow frequency (ULF) wireless communication systems and can be extremely power-efficient compared to traditional electrical antennas in the ULF range. The efficiency of ULF signal generation using magneto-mechanical transmitters (MMTs) is dictated by multiphysical effects from mechanical, magnetic, and electrical domains, leading to an interesting trade space. In this work, we show that an MMT's most power-efficient and most voltage-efficient driving frequencies always differ, forcing designers to sacrifice one efficiency for the other. To address this issue, we propose an efficiency optimization method that minimizes the total impedance of the MMT at the most power-efficient driving frequency, by means of a compensation capacitor added to the electromagnetic actuation coil system. Our experimental results show excellent agreement with our analytical model, and we demonstrate that our approach enables simultaneous maximization of voltage and power efficiencies of an MMT at the same driving frequency. We additionally describe how to apply this optimization method on multiresonator magneto-mechanical arrays and present numerical analysis that predicts much greater improvement factors in systems having larger net magnetic moments and drive coils with larger sizes.