Broadband VLF/LF Transmission from an Electrically-Small Structure via Time-Varying Antenna Properties

High-speed time-varying electromagnetic systems have recently been able to achieve feats that would otherwise be impossible with conventional steady-state solutions. Broadband electrically-small antennas and nonmagnetic unilateral networks are two such systems that have come to fruition through time-varying electronics. Here, we present work aimed at combining these two capabilities in order to effectively radiate wideband VLF/LF signals from a nonreciprocal electrically-small transmitter. We discuss the theory of operation and detailed FDTD simulations that serve to validate the concept. We also explore preliminary results from a low-power prototype as well as improvements to said prototype made by moving from GaAs to GaN technology. Finally, we demonstrate a successful communication link between the time-varying transmitter and a newly designed VLF/ LF electric field receiver.