I don't really understand the physics involved in dxing.  The atmospherics
the ionisphere, and all that.  could someone explain?
--mark KI6DJZ

9 responses total.

This isn't a simple and quick subject, as propagation has a lot of
variables that need to be taken into account.

Start with this page:
http://en.wikipedia.org/wiki/Radio_propagation

Then follow the links of interest there.

You didn't specify if you wanted more information on AM Broadcast,
Shortwave, or specifically ham HF DXing.

I often listen to the radio in my car and noticed recently that at
night I can hear many more (and more distant) AM (medium wave)
stations than I can during the day.  During the day, is the D layer
absorbing signals from the other stations, or merely reflecting
signals from stations less far away because it's lower than the E and
F layers?

The D layer absorbs the signals, which is why the lower HF
frequencies, and MF frequencies, don't propagate well during
the daylight hours. When you can hear an AM Broadcast station
during the day, it is from the groundwave.

This is also why those stations must reduce their broadcasted
power, and HD Radio isn't allowed, during local nighttime.

That makes sense then.  Interesting point about medium wave
HD Radio btw!

I just read, in Popular Communications, that the FCC is
possibly going to allow HD broadcasts at night. There are
people not happy with that possibility.

This really makes me wonder about the decision making processes
the FCC has been using, between this and the whole BPL issue.

Decision making process: "Right, who's going to give us the
most cash?"  ;-)

Surely you're not suggesting our all-knowing Federal regulatory
agencies would be seduced by the all-mighty dollar? How dare
you, sir, how dare you.
</sarcasm>

*snort*

<grin>

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