Introduction To "Radio Communication"

Abstract

The short-wave era in commercial long-distance radio communication began with the revolutionary discovery of the “daylight” wave by Guglielmo Marconi in October 1924, when a series of experiments which had begun in the spring of 1923, systematically culminated in successful daytime transatlantic communication at 32 m of wavelength. Soon after Marconi’s epoch-making discovery, short waves, which in those days were defined as wireless waves below 200 m, began replacing long waves (in the 60 kHz‐150 kHz range, or 5 km‐2 km waves) for transoceanic communications. Short-wave communication with 15 m was soon found to be better than that with 32 m. Short waves became the workhorse of worldwide communications until the late 1960’s, when satellite communications began replacing its functions. Short-wave communication was the main medium with which World War II was conducted. In this reprinted paper (the record of the address Marconi delivered on October 17, 1927, in New York City), Marconi describes the details of this discovery in the context of the contemporary technological state of wireless communications. A short time after Marconi’s 1927 address, Appleton explained the long-distance propagation of the daylight wave through a new mechanism of ionospheric reflection through the “F ” layer that often goes by his name (as opposed to the ionospheric “E” layer, the Heavyside‐Kennelly layer that explained propagation of Marconi’s original transatlantic propagation of “long” waves). Appleton received the Nobel prize in physics in 1947 for the discovery of the ionospheric “F” layer, explaining Marconi’s achievements. The reader is urged to read this reprint of Marconi’s address thoroughly to get a first-hand glimpse of the excitement generated by his pioneering work. II. SHORT WAVES AND THE RADIO AMATEURS The glory of inaugurating the short-wave era in long