Abstract
A LECTURE on the above subject was delivered on Friday evening, November 13, by Dr. J. A. Fleming, to the members of the Wireless Society of London, at the Institution of Electrical Engineers. Dr. Fleming said that the present period of enforced inactivity for all loyal radiotelegraphists, except those engaged at the seat of war, offered an opportunity to reconsider some of the purely scientific questions involved in the art. He proposed therefore to discuss the function of the earth in radiotelegraphy. Apart from the disputed question whether the aerial wires should preferably be earthed at the base or connected to an insulated balancing capacity, it was well known that the nature of the soil or surface between the transmitting and receiving stations had a great effect on the signal strength. This effect depended much upon the wave-length. Thus Dr. L. W. Austin had shown that the ground to the north and north-east of Newport, Rhode island, U.S.A., exercised a powerful absorption on radio-telegraphic waves of about 1000 metres wavelength. Experiments made between Brant Rock wireless station and a U.S. cruiser Birmingham, lying at Newport, showed that whereas electric waves of 3750 metres wavelength suffered little or no absorption in travelling over the 45 miles other than that die to the normal space decrease of energy, waves iooo metres in length lost 95 per cent. of their signalling energy in passing over the same district.
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The Function of the Earth in Radio-Telegraphy . Nature 94, 320–321 (1914). https://doi.org/10.1038/094320a0
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DOI: https://doi.org/10.1038/094320a0