Refraction_of_Hertzian_waves_by_a_paraffin_lens_1897.png
Summary
Description Refraction of Hertzian waves by a paraffin lens 1897.png |
English:
Early experiment demonstrating
refraction
of
microwaves
by a paraffin lens, by
John Ambrose Fleming
in 1897, repeating similar earlier historic experiments around 1894 by
Jagadish Chandra Bose
,
Oliver Lodge
, and
Augusto Righi
. A
spark gap transmitter
A
, consisting of a
dipole antenna
made of two brass rods with a spark gap between them inside an open waveguide, powered by an
induction coil
I
generates a beam of
microwave
radio waves
at a frequency of 1.5 GHz (20 centimeters wavelength). This is focused by the solid
paraffin
lens
L
on a dipole receiving antenna in the box
B
and detected by a
coherer
receiver
, which rang a bell every time the transmitter was pulsed. Fleming demonstrated that the lens actually focused the waves by showing that when it was removed from the apparatus, the unfocused waves from the transmitter were too weak to activate the receiver. The historic importance of quazioptical exeriments like this is that they confirmed that radio waves and light waves are both
electromagnetic waves
, differing only in frequency.
|
Date | |
Source | Retrieved 16 June 2020 from John Ambrose Fleming (1916) The Principles of Electric Wave Telegraphy and Telephony, 3rd Ed. , Longmans, Green, & Co., London, p. 414, fig. 10 on Google Books |
Author | John Ambrose Fleming |
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