July 24, 2018


Hi Friends,

     One of the early guys who spoke of radio waves was Faraday, in Europe. Then came out an American, Maxwell, who wrote on it. They all spoke and wrote about the SINE WAVE, as a wave traveling in space. It is AC in characteristic as how waves are, it shifts polarities. We all know that  a since wave has a positive phase and a negative phase. It was Maxwell who wrote a paper that we can send information using this radio wave. The theory came way ahead of being able to produce sine waves. We also know that Marconi, Italian, registered his patent in England on how to produce sine waves. There no vacuum tubes yet, no semiconductors. Marconi used SPARK GAPS. Yes, he was creating sparks just like the spark in a spark plug of a motorcycle. Did you hear your radio pick up a passing motorcycle? That was how Marconi did it and sent the first trans Atlantic signal to the U.S. Basically, it must have been like the ignition coil in a car or motorcycle. It was all battery and coils. But the sparks he produced was very very broadband. The FCC would have been after him. Fortunately there was no FCC yet! and nobody minded because people did not have sophisticated receivers to hear his sparks! But Marconi had one in the east coast of the U.S., Newfoundland I think. His people heard the spark. How did he built in information. Well, he adopted the Morse Code. He must have found a way to create two distinct sounds of sparks.

     To detect the signal, galena crystals became popular. It became know n as the detector. Then Edison of Ohio, USA came into the picture. He was not concerned about radio. He was concerned about lighting up the streets of Ohio and the entire USA. During his time, dynamos were already known. Faraday and Volta used batteries which DC. Later on, it was discovered that a magnet running around coils of wires produced electricity. It was AC but since the orientation at that time was DC, a commutator was installed in the dynamos to collect all the + and the - separately. So, it was DC dynamos everywhere in the U.S. Edison was a DC believer. All over the place DC current lighted up streets. How? with ARC LAMPS. Two carbon elements continually burning which needed constant adjustments. Edison invented the vacuum light bulb. Since there was no oxygen inside the bulb, the element did not burn.

     Experimenters picked up on Edison's bulb and one of them was Fleming in England. No not Ian Fleming who produced James Bond. they moved on to invent the Fleming valve. Here is a copy-paste from Wikipedia.


The Fleming valve, also called the Fleming oscillation valve, was a thermionic valve or vacuum tube invented in 1904 by Englishman John Ambrose Fleming as a detector for early radio receivers used in electromagnetic wireless telegraphy. It was the first practical vacuum tube and the first thermionic diode, a vacuum tube whose purpose is to conduct current in one direction and block current flowing in the opposite direction. The thermionic diode was later widely used as a rectifier — a device which converts alternating current (AC) into direct current (DC) — in the power supplies of a wide range of electronic devices, until beginning to be replaced by the selenium rectifier in the early 1930s and almost completely replaced by the semiconductor diode in the 1960s. The Fleming valve was the forerunner of all vacuum tubes, which dominated electronics for 50 years. The IEEE has described it as "one of the most important developments in the history of electronics",^[1] and it is on the List of IEEE Milestones for electrical engineering.


Open this link about Faraday:

https://www.bbvaopenmind.com/en/science/.../faraday-electromagnetic-theory-light/

Please copy paste to open.


.This was Faraday in 1856. He spoke of radio waves in 1846.

Electromagnetic waves

This section gives a brief introduction to light and electromagnetic waves.
The idea that light is an electromagnetic wave had occurred to Faraday while Maxwell was still a schoolboy, but Maxwell was the first person to possess a complete set of equations describing the dynamical behaviour of electric and magnetic fields. Believing that Faraday was correct, Maxwell set out to show that his equations have wave-like solutions that propagate through empty space at the speed of light.
Electric and magnetic fields are produced by charges and currents, but these fields also extend into surrounding regions of empty space. For example, charges and currents in the Sun produce electromagnetic fields which travel across almost empty space before reaching sunbathers on a beach on Earth. The detailed relationship between the fields and their sources will not be discussed here. Instead, we take the existence of time-varying electric and magnetic fields for granted, and concentrate on their propagation through space. In empty space, the charge and current densities are equal to zero, so Maxwell's equations become

Our aim is to show that these equations have wave-like solutions which describe oscillating electric and magnetic fields that propagate through space. These wave-like solutions are called electromagnetic waves.


 This link summarizes it all. Hertz ( German) demonstrated the arc transmiter at the end of the 10th century and Marconi made a practical transmitter in the early 20th century.

https://en.wikipedia.org/wiki/Transmitter