I think you have struck the nail on the head Alan.
Current in = Current out is probably only true if the coil is very short, i.e.
this is just an approximation to the truth, which breaks down when the coil is
If there were no wire attached to the top, current in would certainly not equal
current out, so why should a bit of wire stuck on the top make a lot of
difference? The coil would then become a helical antenna and would probably
need a lot of capacitance to bring it to resonance.
73 John, G4CNN
From: "Alan Melia"<[email protected]>
To: "LF-Group"<[email protected]>
Date: Mon May 07 16:41:29 PDT 2001
Subject: LF: re Steve's RF currents
Hi all, It occurs to me that Steve's aerials is just 12m up....no top load,>so
there will be a considerable taper in the current from top to
bottom....not like the heavily top-loaded 'T's and 'L's which are supposed
to have almost constant current in the vertical. Might this difference in
current be just what might be expected in that situation....I think the coil
has to be regarded as part of the aerial. If you assume a linear taper in
current that accounts for about 200mA just by the length of the coil (app.
1m) or its height above ground. Maybe that a bit naive, but then if the
other was losses, that would account for the 400mA.
Fascinating....I am learning a lot.
Cheers de Alan G3NYK
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