. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 118 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. The general principles on which practical radiotelegraphy is based are now so well known that I need only refer to them in the briefest possible manner. Wireless telegraphy, which was made possible by the fields of research thrown open by the work of Faraday, Maxwell, and Hertz, is operated by electric waves, which are created by alternating currents of very high frequency, induced in suitabl
. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 118 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. The general principles on which practical radiotelegraphy is based are now so well known that I need only refer to them in the briefest possible manner. Wireless telegraphy, which was made possible by the fields of research thrown open by the work of Faraday, Maxwell, and Hertz, is operated by electric waves, which are created by alternating currents of very high frequency, induced in suitably placed elevated wires or capacity areas. These waves are received or picked up at a distant station on other elevated conductors tuned to the period of the waves, and the latter are revealed to our senses by means of appropriate detectors. My original system as used in 1896 consisted of the arrangement shown diagrammatically in figure 1, where an elevated or vertical wire was employed. This wire some- times terminated in a capacity or was connected to earth through a spark gap. By using an in- duction coil o r other source of sufficiently high tension electricity sparks were made to jump across the gap; this gave rise to oscillations of high frequency in the elevated conductor and earth, with the result that energy in the form of electric waves was radiated through space. At the receiving station (fig. 2) these waves induced oscillatory currents in a conductor containing a detector, in the form of a coherer, which was usually placed between the elevated conductor and earth. Although this arrangement was extraordinarily efficient in regard to the radiation of electrical energy, it had numerous drawbacks. The electrical capacity of the system was very small, with the result that the small amount of energy in the aerial was thrown into space in an exceedingly short period of time. In other words, the energy, instead of giving rise to a train of waves, was all dissipated after on
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