I initially used one on 73kHz. Two turns of 10mm diameter water pipe,
overall loop dia 3m. Efficiency was about -50dB compared with -40dB for a
modest 7m high T antenna so the loop went in the bin. However, did manage
to communicate on 73kHz over a 20km path to a portable Rx, which was a
record distance then - using wideband CW !
I produced a spreadsheet to calculate loop parameters; at these frequencies
small loops were very difficult to get down to reasonable losses - there was
certainly no comparison with the same amount of copper when used as a wire
antenna.
A pity I threw out the 3m dia loop, it would probably have done quite a good
job on Topband.
===============
On another matter - does this reflector now not reflect messages to the
originator ? This morning I posted the earlier note about magnetometers,
but it never came back to me, but replies did so it obviously got out.
Noticed this at other times too. Other messages seem to be coming in OK.
Lets see if this one comes back..........
Andy G4JNT
-----Original Message-----
From: Paul A. Cianciolo [mailto:[email protected]]
Sent: 2001-06-18 13:38
To: [email protected]
Subject: LF: Anyone using a magnetic loop for 136 Khz?
Hello Folk.
I have had a sudden interest in small manetic transmitting
loops lately.
Have seen manty designs for 160 meters and above but not too
much on LF.
Anyone running one of these at 136Khz? How is the feeding done?\\
Most designs that I have seen use tubing to reduce the I*R
losses. Do to
skin effect I realize that current flows only on the
surface of the conductor. This maseem like a very basic
question but do
current flow on the inside of the tubing?
And if it does of what use is it? Seems to me like it would
not be useful
for radiating purposes since it is inside of a shielded pipe.
Would not a flat strap cable be better?
Thank you
Looking toward 136 Khz!!!!!!!
Paulc
W1VLF
Cloudbounce Webpage http://www.qsl.net/w1vlf/
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