Rediscovering the radio

Thread Starter

Ioanp

Joined Oct 18, 2015
25
I would like to retrace how radio transmissions came about. In other words, I would like to understand the math and physics behind it and possibly reproduce on my own wireless transfer of information and energy from point A to point B.

Does anybody know if such a study already exists? If yes, where would it be?
 

alfacliff

Joined Dec 13, 2013
2,449
first came Maxwell, with the theory, then Hertz with the demonstration, then Tesla, Bose, Marconi and the rest. Also, Steinmetz with the math of how the spark transmitter actually worked.
 

nsaspook

Joined Aug 27, 2009
6,265
A large fraction of technical people don't consider Telsa as a very important character in the development of 'Radio'. His theories of large scale wireless energy transmissions were completely wrong because of his extreme skepticism of the Maxwell/Hertz concept of fields but his designs of high frequency (audio range) alternators lead the way for efficient RF generators later.
 

alfacliff

Joined Dec 13, 2013
2,449
tesla's most important contribution was the introduction of resonance and tuned circuits. marconi systems were basicly untuned extremely broadband spark transmitters and recievers. also, how about all those patents of tesla's that marconi violated when "inventing radio"?
 

joeyd999

Joined Jun 6, 2011
4,239
A large fraction of technical people don't consider Telsa as a very important character in the development of 'Radio'. His theories of large scale wireless energy transmissions were completely wrong because of his extreme skepticism of the Maxwell/Hertz concept of fields but his designs of high frequency (audio range) alternators lead the way for efficient RF generators later.
Are you trying to start a war?
 

nsaspook

Joined Aug 27, 2009
6,265
Are you trying to start a war?
No, I just like to keep Tesla and his great contributions in their proper place. The man was an absolute engineering genius and deserves all the accolades he was given for his real accomplishments but his contribution to radio 'science' was minimal.
 

alfacliff

Joined Dec 13, 2013
2,449
first off, Tesla built radio controlled boats long before marconi "invented" radio. Tesla was a colege trained engineer. and the remark that his contributions to radio "science " was minimal is incorrect., while most others were using untuned spark transmitters, he was using resonance, even modulation to control his boats. Marconi"s system used a ground, spark gap, and antenna as a transmitter, sometimes a capacitor across the spark gap, no tuning at all. basicly he generated some rfi at high voltage with an antenna to make it a bit longer range. tesla's system used a tuned primary, spark excited, inductivly coupled to a resonant secondary and antenna. he also experimented with high frequency alternators coupled to tuned circuits to transmit and recieve CW. one of his circuits used a small arc oscilator to hetrodyne signals in a reciever. arc exciters are better than spark, becasue they give a cleaner continous wave carrier, rather than the racous noise generated by a spark.
 

nsaspook

Joined Aug 27, 2009
6,265
http://earlyradiohistory.us/tesla.htm
Radio, formally defined, is the transmission and reception of electromagnetic radiation -- also known as "radio waves" -- for signalling or other forms of transmitted information. Two of the most celebrated scientific achievements of the 1800s were Clerk Maxwell's mathematical prediction, and Heinrich Hertz's subsequent experimental proof, of the existence of electromagnetic radiation (i.e. radio signals). These two scientific giants showed that a high-frequency alternating electrical current, when sent through an electrical conductor such as a wire antenna, produces electromagnetic radiation, identical to visible light, but with much lower frequencies. A key characteristic of all electromagnetic radiation is that it travels through space as a "transverse wave", usually represented mathematically as the repeating up-and-down tracings of a sine-wave.

Hertz's groundbreaking experiments are best known for showing that radio waves could travel through the air. (Although at the time most scientists still believed in the existence of "the ether", so sometimes they were called "ether waves"). Less well known is that Hertz also showed that, unlike light, radio waves also could travel along the surface of an electrical conductor, such as a wire -- one of his publications was a March, 1889 paper, "On the Propagation of Electric Waves along Wires". In other words, this means that an electrical conductor can act as a "wave guide" for radio signals. It was later discovered, initially by Marconi, that the ground, and especially sea water, also act as waveguides for longwave and mediumwave radio signals, and these "ground waves" (also known as "surface waves", or, in the early days, as "gliding waves") made distant signalling possible, initially to the far side of hills, and later over-the-horizon.

Nikola Tesla always dreamed big. It wasn't just telegraph and telephone wires that offended him, but also electrical power lines, especially the ones running between power stations and consumers. Another thing that made him unique was that, at least through 1919, he didn't believe that the radio signals predicted by Maxwell and experimentally shown by Hertz really existed. He was insistent that no form of unguided "free radiation" could be successfully used for distant communication, instead, what he later called "the true wireless" involved "transmission of electrical energy through the natural medium".
It seems a large number of people see 'Wireless' and think 'Radio'. The term of art 'wireless' as Tesla and many others at the time was not the far field electromagnetic radiation we commonly call radio waves today. The 'facts' speak for themselves on this matter.

http://ieeexplore.ieee.org/stamp/stamp.jsp?reload=true&tp=&arnumber=1694723
 
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alfacliff

Joined Dec 13, 2013
2,449
yes it is the same as we use now, just a bit improved, and different modulation methods. spark transmissions were inherently broadbanded but that was corrected by the advent of CW, continous wave, generated by first alternators and arc transmitters. the range improved with the cleaning up the spectrum used. modulation methods changed from simple of off keying to adding voice, first am then fm. digital modes started with RTTY sent as frequency shift keying, and fax over the air. the pioneers of radio did a pretty good job of getting the basics down for what was to follow. Tinkerers, inverntors, engineers, scientists, and mathemeticians all worked to "invent " radio as we know today.
 

nsaspook

Joined Aug 27, 2009
6,265
yes it is the same as we use now, just a bit improved, and different modulation methods. spark transmissions were inherently broadbanded but that was corrected by the advent of CW, continous wave, generated by first alternators and arc transmitters. the range improved with the cleaning up the spectrum used. modulation methods changed from simple of off keying to adding voice, first am then fm. digital modes started with RTTY sent as frequency shift keying, and fax over the air. the pioneers of radio did a pretty good job of getting the basics down for what was to follow. Tinkerers, inverntors, engineers, scientists, and mathemeticians all worked to "invent " radio as we know today.
Tesla talked about induction not transverse radio waves but I agree with the rest of your comments.
 
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