Sixty years ago this month, the February 1962 issue of Popular Mechanics carried this hint for using an outdoor antenna in the fallout shelter. The magazine noted that the shielding required for fallout protection could also shield against vital radio broadcasts. Since most radios didn’t have an external antenna jack, the magazine showed how to add one. A small coil was placed over the loopstick antenna, and that coil was hooked to an outdoor antenna. For optimal reception, you would tune in a station close to 640 or 1240, the CONELRAD frequencies, and slide the coil along until the signal was strongest. At that point, you would add a little cement to fix the coil in place.
The antenna could be unplugged when in normal use, but quickly put to work in the shelter in time of emergency.