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KF5JRV > TECH 14.01.17 14:17l 65 Lines 7415 Bytes #999 (0) @ WW
BID : 8809_KF5JRV
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Subj: Amateur Radio Foundations
Path: IW8PGT<IR2UBX<IZ3LSV<IK6ZDE<F1OYP<KQ0I<KA3BVJ<N3IP<NS2B<KF5JRV
Sent: 170114/1315Z 8809@KF5JRV.#NWAR.AR.USA.NA BPQ6.0.13
The foundation of the hobby of amateur radio were set in place with some of the early discoveries that were made into electrical current, then magnetism and then the mathematical proof of electromagnetic waves, and finally their discovery and use.
Many pioneers were involved in this history, some working as professionals, others as amateur experimenters.
Each of these people contributed to the furthering of electrical and then radio technology, and many being purely amateurs added their bit, enabling the hobby of amateur radio to come into existence.
History of amateur radio: basic foundations
Some of the first discoveries that set the foundations for radio and amateur radio were set in place by some of the key figures in History.
Luigi Galvani was an early pioneer. In 1780, he discovered that the muscles of dead frogs' legs twitched when struck by an electrical spark. Galvani coined the term 'animal electricity' to describe a force that activated muscles. At the time electricity was not understood, and Galvani thought that the movement was caused by an electrical fluid that was carried to the muscles by the nerves.
The next step was taken by Alessandro Volta who invented the electrical battery. This enabled electrical currents to be created, rather than the static electricity that had previously been accessible. He invented the Voltaic pile in 1799, although he previously used a 'Crown of Cups' to provide a battery.
Other pioneers like the French scientist Ampere followed. Ampere began developing a mathematical and physical theory to understand the relationship between electricity and magnetism having seen that a current flowing in a wire deflected the needle of a compass. He also showed that two parallel wires with currents flowing in opposite directions repelled each other.
Another key figure in setting he foundations for radio and later amateur radio was Michael Faraday. Although he received very little formal education, he went on to be one of the most influential scientists of all time. He researched many areas, many of which were associated with electrical science as well as chemistry. In terms of his work that can directly be linked to the development of radio, he established the concept of the electromagnetic field, that magnetism could affect light rays and the fact that there was an underlying relationship between them.
Joseph Henry in the USA had also been looking at electromagnets and he discovered the electromagnetic phenomenon of self-inductance.
Radio signals in theory
With the basic electrical concepts in place, the next step was for these developed towards the idea of electromagnetic waves and then radio transmissions.
A brilliant Scottish scientist named James Clerk Maxwell set the next foundations in place.
Maxwell was a theoretical scientist and sought to express physics in terms of mathematical relationships.
Maxwell was well ahead of his time, and was able to prove that a phenomenon called electromagnetic waves existed, even though nobody could relate to what they were. He even deduced their speed of travel and some saw a coincidence between the speed of electromagnetic waves and that of light which had been measured by other scientists.
Maxwell's work culminated in 1873 with the publication of a book called "A Treatise on Electricity and Magnetism". In this he developed equations, now known as Maxwell's Equations that defined electromagnetic waves. However Maxwell never gave a practical demonstration of his theories.
Radio signals discovered
Trying to determine the first person to see or use radio waves is difficult. A number of people reported what we now know to be radio waves, but then it was not obvious.
A person called Professor D E Hughes built what was a spark gap transmitter in his house and was able to detect the sparks at a range of over 400 metres.
Other people as well undertook similar experiments and were able to successfully detect the sparks at varying distances.
Unfortunately these people did not link these effects to Maxwell's electromagnetic waves and therefore they cannot be honoured with being the first to identify how the effect occurred.
The honour of discovering radio waves fell to a German scientist named Heinrich Hertz. He performed several experiments that demonstrated their presence beyond doubt. His most famous experiment Hertz used two coils of the same size that were placed a few metres apart. Each loop had a spark gap in it. When a spark was made to cross the gap in the first coil, Hertz showed that a similar but smaller spark jumped the gap in the second.
The result of Hertz's were published in many journals and as a result hertz was attributed with having discovered these waves. For some years afterwards they even bore his name being called 'Hertzian Waves.'
The phenomenon of radio waves gained a lot of publicity - the fact that signals could travel between two points with no wire even held a form of magical mystery and public demonstrations were sometimes given. This fuelled the interest of many up and coming radio amateurs, and can be seen as a key period in the history of ham radio.
Coherers arrive
Using Hertz's apparatus where the signal was detected by a second loop with a gap across which a second spark jumped required a very large signal to be received and this severely limited the range.
Several people started to perform experiments and develop radio technology further. One major step was made by a person named Professor Onesti who showed that iron filings placed in a glass tube with electrodes at either end could be made to stick together or cohere when a high voltage was placed across the electrodes. Once the filings had cohered they were able to pass an electric current which could be used to complete a second circuit. This was taken a stage further by Edouard Branley a French inventor, physicist and professor at the Institut Catholique de Paris who discovered the iron filings would cohere in the vicinity of an electrical discharge. Finally Oliver Lodge in Britain used this discovery to detect Hertzian waves. Using this system he managed to receive signals over a distance of about 150 yards.
Marconi develops radio further
As the technology behind radio started to be developed, many others were interested, although initially it was seen more of a curiosity rather than a technology that could be used.
Marconi was different: he saw that it could be a key form of communication, especially for shipping where no wired telegraphs could operate.
Initially Marconi undertook his experiments at his parents' home in Italy, but finding no commercial interest there, he came to Britain with his mother.Marconi steadily increased the distances over which he could transmit. In 1898 he used wire-less (as it was then called) to report on the Kingstown Regatta for a Dublin newspaper. A year later he made the first international contact by communicating between a station at South Foreland, England and another located at Wimereux near Bologne, in France. This was a distance of about 50 km.
Then against all the odds he planned a transatlantic transmission, finally succeeding by hearing signals across the Atlantic on 12 December 1901. In just three years he had increased the distances that could be covered from a kilometre or so to the traversing of the Atlantic.
73 Scott KF5JRV
KF5JRV.#NWAR.AR.USA.NA
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