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Have you done radio physics experiments?

Jul 29th 2011, 07:58

LeeM

Joined: Jul 28th 2010, 06:46
Total Topics: 0
Total Posts: 0
Hello this is Lee, AG6CB. I am interested in hearing from a ham or hams who have done radio experiments and physics study that explore the fundamental puzzle of how radio waves produce action or communication at a distance.

First I am asking for a mention of book titles and web sites that you have found that have helped with your version of an inquiry into the fundamental nature underlying a radio wave.

For experiments, I'm thinking about setting up a pair of wire loops and driving one wire loop with a very small signal and watching the other loop with an oscilloscope. This is a lot like the original Marconi and Hertz experiments.

Now what will I see when I drive the sending loop with a single cycle of rf electricity? How about two cycles? Is there a wave front delay? How many cycles are needed for the receiving loop to develop magnetic fields and electrical potential?

An interesting thing is there is a mathematics package called "Sage" and this package has the ability to solve differential equations. What will happen if I measure what I observe and try actually running a real copy of the Maxwell wave equation with real data from the experiment?

Now, can I go beyond the wave equation and do the comparable math using what the physicists say are the actual subatomic particles involved?
Aug 4th 2011, 01:33

KC7ZO

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I set up a nice experiment once for a batch of boy scouts. Two wires strung up side by side. Used a signal generator to put a signal on one and a meter on the other. Moved the frequency up from sound waves into ultra sound then into low RF. A very visible way of seeing radio at work.
Aug 7th 2011, 02:50

ka9wgn

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Having a big interest in wave physics, one area I've always wanted to set up some "observability" experiments is how antennas establish their directionality. And it's more than just knowing that in some directions, the signal cancels out while in other directions it adds, because that alone does not explain the whole effect.

A single radiator (fed with say 100W) will give a specific field strength at some distance. If you split that 100W into two radiators so each is now at 50W, some people might think that in the direction where the phasing adds together, you'd just have the original field strength. If that's all that ever happened, antennas would not have gain. But in fact at that point in the far field, the strength is now doubled even though the total power radiated remains the same.

That should be a relatively simple experiment to set up to show the real effect. How to illustrate why this happens would be a lot harder (the only "illustration" I've ever seen is mathematics).

BTW, I've seen a few different variations on this, addressing different wave effects. In physics they are called "the two slit experiment" where it is argued that individual particles not just can, but always will, behave like waves. I personally believe waves are the foundation of all existence. Related effects of interest include X-ray crystallography (scale it way up and you can do the same thing at radio frequency) and diffraction (scale that way up and you can consider knife edge effects of hills on radio propagation). Fun stuff, these waves.
Aug 18th 2011, 21:00

KM3F

Joined: Mar 6th 2008, 13:50
Total Topics: 0
Total Posts: 0
For a signal gain in any direction, I alway learned from known antenna theory that power applied to the radiating elements (total antenna assembly), no matter in what configuration, must alter the radiation field pattern to produce a higher concentrated field in a given direction.
Since an antenna can not make or produce power on it's own, it can only, by it's configuration and using phase addition/canellation process, alter the radiated power to a concentration in a preferred direction (gain type antennas).
In contrast, a vertical antenna usually does not concentrate it's field in any peticular direction radially. Again here one would have to compress the radiated pattern vertically to get gain at a distance.
Bottom line is you have to concentrate the power applied to favor a direction in order to see a rise in field strength.
This is done by phase additions and cancellations using mechanical configurations and spacing of the elements.
In phase addition and cancellation there are time delay elements involved that vary with element spacing, element shapes, ground effects and losses.
What other mechanics would be used if this does not explain the science?
Aug 24th 2011, 01:47

AA6E

Joined: Apr 4th 1998, 00:00
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Total Posts: 0
There are some nice YouTube videos about directional antennas. I like this one by Diana Eng http://www.youtube.com/watch?v=lslHtCUSfN4

73 de AA6E
Martin
Dec 15th, 19:54

WD4PLB

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Hello Sir:
I am Walter / WD4PLB.
I am looking for anyone who has build a working tunable light receiver and transmitter?
Thank you.
E-Mail: wd4plb1@yahoo.com

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