ELF-VLF Transmissions via Motion-Induced Radiation of Charges

Mechanical antennas have garnered interest as a potential method of transmitting extremely low-frequency (ELF) to very-low-frequency (VLF) radiation in a manner that possesses a high efficiency of radiation and a low form factor. In this article, we investigate these claims by solving for the exact field solutions for one particular example, a rotational-oscillating charged thin spherical shell. The field solutions allow the analysis of the radiation pattern, radiation efficiency, and spectral output as a function of several geometric and kinematic quantities of the sphere. The results indicate that high efficiency with a low form-factor appears to be plausible, assuming that the required mechanical conditions for the motion can be achieved.