Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>
At 10:49 AM 10/29/2005, you wrote:
Original poster: Ed Phillips <evp@xxxxxxxxxxx>
"Like it
is been said before, "if it cant kill ya it aint a real radio" and Tesla
did invent them also.
Rich , kd0zz , from the middle of Missouri"
Sorry, but he didn't. His gas-filled bulbs were for lighting
purposes and no amplification was involved. Follow the
Edison-Fleming-DeForest trail.
Hmm. is amplification necessary?
J.C. Bose transmitted radio waves at 60 GHz in the late 19th century
in Calcutta. He also identified them as being like light, in that
they were polarizable, could refract, etc. all of which were
predicted by Maxwell.
Spark gap transmitter (using a cavity resonator) and a point
contact detector.
google for "bose calcutta millimeter" for lots of useful info.
"
In 1895 Bose gave his first public demonstration of electromagnetic
waves, using them to ring a bell remotely and to explode some
gunpowder. In 1896 the Daily Chronicle of England reported: "The
inventor (J.C. Bose) has transmitted signals to a distance of nearly
a mile and herein lies the first and obvious and exceedingly
valuable application of this new theoretical marvel." Popov in
Russia was doing similar experiments, but had written in December
1895 that he was still entertaining the hope of remote signalling
with radio waves. The first successful wireless signalling
experiment by Marconi on Salisbury Plain in England was not until
May 1897. The 1895 public demonstration by Bose in Calcutta predates
all these experiments. Invited by Lord Rayleigh, in 1897 Bose
reported on his microwave (millimeter-wave) experiments to the Royal
Institution and other societies in England [8]. The wavelengths he
used ranged from 2.5 cm to 5 mm.
"
Bose was interested in scientific inquiry. Marconi was interested in
commercializing.
The work by Bose was way, way ahead of its time. His mm wave
work included rectangular waveguides, EM horns and he made a lot of
material measurements which were analogous to those of Hertz,
except at about 100 times the frequency. Fascinating reading. For
some reason he's not very well known but should be. Unlike Tesla,
he demonstrated his work in public and wrote clear explanations of it.
As for Marconi, you're exactly right. He started off by studying
under Professor Righi after he'd read about Hertz's work. His
objective soon developed into commercialization of "wireless
telegraphy" and he pursued that objective quite successfully. "Word
on the street" is that he stole Tesla's ideas and his double-tuned
transmitter and receiver circuits but I can't buy that. He came up
with similar arrangements but, if he'd really stolen something from
Tesla, he'd have done better earlier. His receivers and his
"jigger" are really mickey mouse! Tesla had prior art but I can't
belive that as bright a kid as Marconi would have done what he did
if he'd read Tesla's patents, which are pretty clear as to
construction techniques.