Abstract
THE arts of wireless telegraphy and telephony involve the use in the receiving circuit of some device named a detector, which is sensitive to electric oscillations of very high frequency. In the earliest years of radiotelegraphy the appliance used was the so-called coherer, in which a small mass of metallic filings or an imperfect contact between two pieces of metal was converted into a better conductor by the passage through it of the high-frequency oscillations. All the various forms of coherer have now been abandoned and are no longer used as detectors. In modern radiotelegraphy, so far as regards the spark or damped-wave system, only three types of detector are at present in practical use. The first of these is the magnetic detector, chiefly the rotating band form, invented by Marconi; the second type is some form of rectifying contact or crystal, such as the carborundum detector due to Dunwoody, or the zincite-chalcopyrite rectifier of Pickard; and the third is some modification of the thermionic detector, or Fleming oscillation valve.
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Thermionic Detectors in Wireless Telegraphy and Telephony . Nature 99, 105–108 (1917). https://doi.org/10.1038/099105a0
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DOI: https://doi.org/10.1038/099105a0