Ultra-Wideband Transmission Using Sub-wavelength Antennas on Airborne Platforms

Engineers designing transmitting antennas at long wavelengths have for decades struggled to make antennas compact, efficient, and broadband. These challenges are especially pronounced in the Very Low Frequency (VLF, 3-30 kHz) band, where wavelengths are 10-100 km. Existing VLF transmitters have either extremely short range, or extremely large size with little bandwidth. Solving this problem would impact several defense and civilian applications, including hemisphere-scale subsea communications, underground sensing and detection, navigation and timing, and even space radiation belt remediation. We propose a radical new antenna concept in which we use high-speed time-variation to break the fundamental limits inherent to conventional antennas. Conventional impedance-matching techniques work only in a narrow frequency band, but our technique is a time-domain matching scheme which inherently works at all frequencies. The limitation is the need for components that can simultaneously handle high-speed (ns-scale) and high power. In Phase I, we will investigate available and customizable components, and explore the achievable trade space of bandwidth-free antenna specifications. An existing proof-of-concept will be scaled it up to a higher-power prototype, enabling groundbreaking demonstrations. Concepts for an even higher power prototype that could be built in a Phase II will be designed, enabling demonstrations to build commercial interest.