That;s a pretty bad example of an AM "transmitter" and I'll leave that
side of things alone.

If you really want to find out how it all works, it comes down to
Maxwells equations - see wikipedia
<http://en.wikipedia.org/wiki/Maxwells_equations> although it's pretty
heavy going.

Personally I understand it no more now than I did in engineering class in 1976!


Essentially the antenna and ground plane behave like a resistive load
for the correct combination of physical dimensions and frequency. The
power that would be dissipated in the equiv. resistor is radiated
instead (mostly anyway, all going well). The exact situation that
causes the radiation is the complicated part above.

I have my own way of trying to understand how this happens but I won;t
try & explain it  here because it's almost certainly wrong and is
likely to cause more confusion than enlightenment!

Hope this somehow assists.

RP




On 31 March 2010 18:27, solarwind <x.solarwind.x@gmail.com> wrote:
> I've been very interested in electrical engineering and radio
> recently. I've been trying to learn how radio waves tie into
> electrical engineering. How do we create them? How do we receive them?
> I've read the howstuffworks article as well as some Wikipedia pages on
> the matter, but still do not know exactly how they "work".
>
> For example, a very simple 1 MHz AM transmitter is described here:
> http://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html
>
> I am referring to the image here:
> http://sci-toys.com/scitoys/scitoys/radio/xmitter_schematic.gif
>
> I understand that the top left pin of the crystal oscillator is the
> input for some voltage. So assuming that I provide a steady +5 volts
> on that pin, what will I see on the output pin (top right)? Will I see
> a 1 MHz wave with a peak voltage of +5 volts? Or will it have an RMS
> voltage of 5 volts?
>
> How is the radio wave generated in this case? If I stick an
> appropriately sized antenna on the output pin, how is the radio wave
> generated? Why is it generated? Is it because of the oscillating
> potential difference across the output pin and ground?
>
> What governs the output power of the radio wave? How do we generate a
> more "powerful" signal? Assuming the photon theory of electromagnetic
> radiation (if that is the correct theory to use here), does the output
> power refer to the number of photons emitted/time? If so, how do we
> increase the power? And why are the photons emitted in the first
> place?
>
> On the receiving end, assuming a properly sized antenna, how is the
> radio wave "received"? When a radio wave strikes the antenna, what
> happens? If I were to have a long, straight piece of wire and clip two
> terminals of a sensitive oscilloscope to each end of that wire, will I
> be able to see the wave (assuming a powerful enough transmitter)? If
> not, why not?
>
> I know bits and pieces of things but I'm still not able to see the big
> picture here. I can only understand this stuff if I know the
> fundamentals on a very low level.
>
> I'm really trying to learn this stuff, and I have searched in several
> books and on the Internet, but it is proving to be a difficult task to
> find this information. I know you guys are the best people to ask. So
> here I am.
> --
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> http://mailman.mit.edu/mailman/listinfo/piclist
>
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