Antenna Now a Loud Speaker
RADIO “freaks” or hearing of programs without apparatus, are reported occasionally; but are usually hard to verify. However, an occurrence at the Hilversum (Holland) station, reported by no less an authority than Dr. Balthasar van der Pol, in a letter to Nature, is well authenticated by competent observation. Increased power, during exceedingly dry weather, was followed by the appearance of a “coronal” discharge—that is, light surrounding the antenna wires, produced, of course, by the ionization of gas affected by the leakage of electrons from the wires. The corona, however, appeared in the shape of balls of light, a few inches in diameter, first at one end of an outside wire, and then inside. When the power of the station was reduced to its normal figure—about 10 kilowatts, 296 meters—the light disappeared. In addition to being luminous, the antenna was loudly audible.
The program of the station was heard by passers-by, as sound from the antenna, up to a distance of a mile, on later high-power experiments. The action is undoubtedly similar to that of the glow-discharge loud speaker, with which interesting experiments have been performed in the past; but needs voltage too high for ordinary use.