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Archive for November 6th, 2010

The cacophony of the Radio Frequency Spectrum ( and Guide)

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The wireless world is taken for granted – from the low frequencies that deliver the time to your “Atomic Clock” and AM broadcast Radio, through RF frequencies that provide digital television, cell phone infrastructure, and home networking, up through the satellites that guide you through GPS and provide global communications.

If you could see RF it would be a cacophony of signals.  Did you ever wonder how all this is arranged and packed into the RF spectrum?  Well, I found this wall size chart that lays it all out for your scrutiny.  Maybe you want to take a look-see

Look and take a wall chart of the RF Spectrum Allocation from 3 kHz to 300 GHz –
https://frrl.files.wordpress.com/2010/11/frequency-allo-chart.jpg

Historical Perspective

When you take a look at the complexity of that RF spectrum allocation chart think about this.  None of that existed 150 years ago.  All of this are the result of  discoveries, formulations, and inventions of great men.

The first comprehensive formulation of the behaviour of Electromagnetic waves was given by James Clerk Maxwell in 1861.  And, as Newton said about his work, “I have stood on the shoulders of giants” so did Maxwell.  Those giants were Faraday, Gauss, Ampere, and many more.

The precise formulation of the time-space laws was the work of Maxwell. Imagine his feelings when the differential equations he had formulated proved to him that electromagnetic fields spread in the form of polarised waves, and at the speed of light! To few men in the world has such an experience been vouchsafed . . it took physicists some decades to grasp the full significance of Maxwell’s discovery, so bold was the leap that his genius forced upon the conceptions of his fellow-workers                                                           —(Science, May 24, 1940)

Much of what Maxwell published is highly mathematical in nature.  However, he did write for the general populace in such places a Popular Science.  For example, here is an article of Maxwell from 1876 … regarding protection of  a gunpowder-manufactory from lightning strikes.  What could be more practical than this?  Compare this to some of his other papers.

What we really wish is, to prevent the possibility of an electric discharge taking place within a certain region, say in the inside of a gunpowder-manufactory. If this is clearly laid down as our object, the method of securing it is equally clear…

Popular Science Monthly/Volume 10/December 1876 – The Protection of Buildings from Lightning

Resources

Read more about Maxwell’s equations –
http://en.wikipedia.org/wiki/Maxwell’s_equations

Read some published papers of Maxwell –
http://en.wikisource.org/wiki/Author:James_Clerk_Maxwell

Written by frrl

November 6, 2010 at 2:39 am

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