Seventy-five years ago this month, the March 1944 issue of Radio Craft magazine presented this idea of how invading forces could blanket the enemy with radio by sky. The idea was to alert civilians as to the invasion and give instructions. The expendable 500 watt transmitters shown here would be dropped over the teritory in question and would broadcast a prerecorded message from magnetic tape or wire. Another possibility would be to drop PA systems, which would begin playing at 3000-4000 feet.

The advantage of this system was said to be that the aircraft could leave the area immediately. In more recent times, the U.S. military has, indeed used airborne transmitters, but stationed in the aircraft.