USA 1957 3¢

USA stamp for the International Geophysical Year - IGY (1957-1958). During the IGY, many ionospheric research projects were carried out, some of them involving amateur radio.

The peak solar conditions on 1957-1958, with a SSN of 285 in March 1958, resulted in a major boost in amateur radio, as many young hams managed to have worldwide QSOs on 28 MHz with modest stations.

Many propagation beacons were installed during IGY; these included amateur radio beacons OZ7IGY and GB3IGY (later GB3RAL) on 144 MHz, which are still operational, as well as the now defunct DM3IGY in East Germany on 28001 kHz.