Foxhole radio

The maker of the first foxhole radio is unknown, but it was almost certainly invented by a soldier stationed at the Anzio beachhead during the stalemate of February – May 1944.

[4] That radio was built by Private Eldon Phelps of Enid, Oklahoma, who later claimed to have invented the design.

It was fairly crude, a razor blade stuck into a piece of wood acted as the detector, and the end of the antenna wire served as a cat whisker.

Many veterans of Anzio refer to the female announcer they heard as "Axis Sally", the nickname usually used when referring to propagandist Mildred Gillars, however Gillars broadcast from Berlin, and the men at Anzio were more likely hearing Rita Zucca, who broadcast from Rome.

The G.I.s would listen at night near the front lines to phonograph records played on a radio station in Rome.

The oxide layer on the blade and the point contact of the pencil lead form a semiconductor Schottky diode and only allow current to pass in one direction.

Only certain sites on the blade acted as diodes, so the soldier moved the pencil lead around on the surface until the radio station was heard in the earphones.

By varying the inductance of the coil with a sliding contact arm, a crystal radio can be tuned to receive different frequencies.

In one case a soldier, Richard Lucas, built earphones by binding four nails together with cloth then winding wire and dripping wax over the turns.