Lodge_spark_oscillator_1894.png
Summary
Description Lodge spark oscillator 1894.png |
English:
Drawing of an early
spark radio transmitter
built by British physicist
Oliver Lodge
for a lecture-demonstration before the British Royal Society 1 June 1894 on the occasion of Heinrich Hertz's death, which was later published as a book. It consists of a 5 in. metal ball resonator flanked by two 1/2 inch metal balls separated by spark gaps. When high voltage pulses from an
induction coil
are applied to the side balls, the current jumps the gaps to get from one side ball to the other through the center ball. The sparks excite brief
standing wave
oscillations in the center ball, which emits the energy as pulses of
microwaves
. Lodge demonstrated that the waves could be detected by a coherer at a distance of 20-30 yards (20-30 m).
The source says wavelength of the waves emitted is about 1.5 times the diameter of the center resonator ball, which for a 5" ball would be 19 cm, or a frequency of 2.5 GHz. The ball is a highly damped oscillator, only producing a few waves before the oscillations die out. |
Date | |
Source | Retrieved 21 February 2018 from Silvanus Phillips Thompson (1897) Light Visible and Invisible: A Series of Lectures Delivered at the Royal Institution of Great Britain, at Christmas, 1896 , The MacMillan Co., New York, p. 222, fig. 121a on Google Books |
Author | Sylvanus P. Thompson |
Licensing
Public domain Public domain false false |
This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 70 years or fewer . This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office ) before January 1, 1929. |
|
This file has been identified as being free of known restrictions under copyright law, including all related and neighboring rights. |
https://creativecommons.org/publicdomain/mark/1.0/ PDM Creative Commons Public Domain Mark 1.0 false false