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Dear Rik, LF group,
----- Original Message -----
Sent: Monday, December 13, 2004 11:34
AM
Subject: Re: LF: Hoar-Frost and Antenna
Losses
Hi Tom,
few weeks ago the item of wet wood in/near a loading coil
was discussed and it seemed to increase the losses. But these would be
"magnetic loss" while at the antenna it is the dielectric loss that
counts.
I don't think so - bear in mind that the loading
coil will be grounded at one end, and have the full antenna votage at the other,
so as well as the magnetic field of the coil, there will also be an intense
electric field. So the dielectric losses in the coil materials will also be very
important.
BTW, the de-icing article is interesting - getting
a 1m long "antenna" tuned up on 100kHz is quite impressive - they have used a
set of ferrite-cored loading coils in series, immersed in oil to improve
insulation. Allthough in spite of this, the Q of about 200 they got wasn't the
best, and they seem to have had voltage breakdown problems, as you might expect.
I wonder why they didn't use an air-cored loading coil?
Cheers, Jim Moritz
73 de M0BMU
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