Drones have quickly become a common part of our everyday world—used in everything from aerial photography and farming to security and delivery services. But as their numbers grow, so do the problems. Not every drone is used with good intentions. Whether it’s buzzing too close to an airport, spying on a secure facility, or carrying…

The world of radio communication covers an extremely wide frequency spectrum, but most everyday applications focus on the VHF, UHF, and SHF bands. In contrast, there are extremely low frequency ranges such as VLF (Very Low Frequency: 3–30 kHz) and ELF (Extremely Low Frequency: 3–300 Hz), which, due to their unique physical properties, offer special…