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Old December 22nd 10, 10:56 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Dec 2010
Posts: 21
Default SWL for Newbies (was: Balcony Antenna for Shortwave Listening)

Hello,

On Fri, 17 Dec 2010 09:20:48 -0800, Richard Clark wrote:

Reg Edward's software, that you already have access to, will answer that
far faster than asking here. Reason for that is because of all the
variables that come into play. You can judge for yourself when you
enter them into the program and observe what results are returned.


Tonight and yesterday night I played with my experimentation board
(loop...s on my shelves).

I have a 4 loops (square) web :
1 - 8 turns - 1.5 m /side
2 - 3 turns - 1.0m /side
3 - 1 turn - 0.8m /side
4 - 1 turn- 0.65m /side

Each one is inside the other one.

I used the second to be the matching one from the previous, the firts.
The third, to be the mathcing one of the second, etc.

The resonant one gets a variable air capacitor (I change it every time I
need to go higher....).

Very interesting, indeed.

If I understand well, the loop gets the role of inductance and the
capacitor the role of the capacitance... (Lapalisse...). Matching both
gets the best result for a given frequency. I succeed in making apparent
signals that I was not aware of... With this antenna I can tune in the
frequency from 300 KHz to near 7300 KHz... Completely amazing. That's the
first time I can exactly see (thanks to the waterfall information
display) how it does increase, not only the signal, but what's more
important, the signal/noise ratio. I understand now how this is very
important...

What I can see, is that depending on the size of the loop and the
frequency I am monitoring, the variable capacitor may or may not be very
difficult to use, and the bandwidth lack of noise, narrow or wide...
Interesting to see that it is possible to increase the signal without
increasing a lot the signal/noise ratio (better than nothing . But you
can't play when the signal is too weak....

I am quite happy. It does not tell anything about the antenna efficiency,
but it helps me understand how it works. I get somebody in my family who
is a physics teacher... I need to ask her information about "RLC
oscillators for newbies" to be able to put some rational things upon my
experimentations

To do next :
- Try to carry out the tiny preselector from Wim (need to find some coper
wire... And need to try to recover some old radio parts to play with....
(get some ferrite rods, low value variable capacitors, etc.)
- Try to get some time, and some place, to play with long wires, dipoles
and their related matching systems...

Sebastien.
 
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