ADF (Automatic Direction Finder) radio waves are propagated as ground waves and/or sky waves. Problems associated with ADF are inherent in the frequency range that ...

Initially, airborne lightning detection was an unintended byproduct of older radios like the ADF, which pilots learned to use as a crude thunderstorm avoidance tool. Dedicated "sferics" devices such ...

Click to open image viewer. IIIF provides researchers rich metadata and media viewing options for comparison of works across cultural heritage collections. Visit the IIIF page to learn more.