Institute for Telecommunication Sciences / December 1941

December 1941: FCC Suspends All Amateur Radio Use During Wartime

On December 7, 1941, Japanese planes attacked Pearl Harbor, Hawaii, decimating the U.S. Pacific fleet. This act brought the United States into World War II. For many, it was a day that the world changed forever. The National Bureau of Standards Radio Section changed forever, too. The day after Pearl Harbor was attacked, the FCC issued a formal order suspending all amateur radio operations for the duration of the war. The Bureau immediately renewed its close ties with the Navy and the Army Signal Corps. By the summer of 1942, the Radio Section was renamed the Interservice Radio Propagation Laboratory (IRPL) and its work was directed by the National Defense Research Council. Radar was a new technology and IRPL researchers worked to make it better and to fool the enemy devices. IRPL worked with Very Long Frequency (VLF) radio waves to improve direction finders for ships and planes. They improved weather stations so that the military could drop them behind enemy lines for planning. One team worked to create radio sensors that could detonate ordinance. NBS had begun to map the ionosphere several years previously, and in 1942 the IRPL began to issue quarterly predictions of the best frequencies for military communication. This propagation prediction work became the primary thrust of the IRPL and its successor laboratories for 20 years. Today ITS continues to work with the military in times of need just as the IRPL did. Many Department of Defense components use ITS’s Propagation Modeling Website for wireless communication planning, and ITS is working closely with the Defense Spectrum Organization to make spectrum sharing work in frequencies now used by military radars and communication systems.