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Message-ID: <8CA4D9371AE446EDAA7576F42D258CF1@JimPC>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
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Date: Tue, 30 Aug 2011 23:57:30 +0100
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Subject: LF: Re: Ferrite wideband antennas?
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Dear Peter, LF Group,

----- Original Message ----- 
From: "pws" <pws@legal-medicine.de>
> These rods are working fine even at VLF. But according to my own 
> experiences in the late 90th bundling is not worth the effort. Two tight 
> (!) stacked 15cm rods achieved better SNR compared to a bundle of 7 rods.
>

I would be interested to know what method you used to determine SNR for the 
different rod configurations. In my experiments, the difficult thing is to 
measure the noise level of the antenna itself, due to the fact that it *is* 
an antenna and usually picks up plenty of noise from external sources. The 
"dummy antenna" consisting of a screened inductor with the same inductance 
and Q as the rod works OK, but not very convenient if you want to try 
several different rod configurations with varying L and Q. Another 
possibility is a screened enclosure to exclude all external fields, but that 
would have to be quite big not to de-tune or increase losses in the antenna, 
as you mentioned.

Cheers, Jim Moritz
73 de M0BMU