Millisign battery-less RFID tag guides drones without relying on cameras, GPS

https://newatlas.com/drones/millisign-guides-drones-rfid-tags/

"big landing-pad-based RFID tag receives radio signal from drone-based millimeter wave radar unit taking place of handheld RFID reader, and transmits response back to drone... response indicates tag's/pad's location relative to drone, so easily located, and more intense received signals indicates drone is closer... tags incorporate corner reflectors enabling signals over wide 3D angle... less installation, maintenance and no need for imaging, unlike GPS... tag can be read by an airborne drone from a distance of 33 to 49 ft."