Hi Alan,
We'll see. I just bought 16 pcs. 140 mm length and 8 mm diameter ferrite
rods for 30 EUR (transport included) on ebay! 16 were available. The mu
is 400, as written there. I hope the ferrite material is suitable for LF...
At least it will be worth the fun and for learning a bit about these
antennas for amateur LF! I will compare to conventional antennas.
So i can play with that type of "magic" antenna. Otherwise i could take
e.g. 7 psc in parallel and that 2x in series. Should be OK for /p
operation...
73, Stefan/DK7FC
Am 15.08.2011 01:58, schrieb Alan Melia:
I am afraid the tone of the article makes me a skeptic :-)) but if his first
former was 12mm diam and his bigger pictured one a120mm diameter the factor
A =100 in the conventional loop equation....so 20dB ...??????? extra
ferrite cross sectional area does help too, plus bigger former less turns
for the inductance less copper loss, higher Q (also increases the output).
Better but no magic!
For some experimental measurements see a Electonics World article on Loops
by a couple of Itallian amatuers (app 2004 or 2005). Having said that there
may be some mileage in not winding the coil direct on the ferrite. Ferrite
is a lossy "semi-conductor" .It might be interesting to screen the core
electrostatically from the coil (it need a logitudinal slot to avoid a
shorted turn effect.) ....but this has probably been tried by many before.
Accurate comparative measurements on a reliable signal like DCF39 would be
much more interesting.
Alan G3NYK
----- Original Message -----
From: "Stefan Schäfer"<[email protected]>
To:<[email protected]>
Sent: Monday, August 15, 2011 12:08 AM
Subject: Re: LF: Ferrite RX antennas
Interesting!
Can anyone of the experts comment on this concept?
After scrolling down through pages of text i just found a few photos.
The mechanical concept is clear.
But the author appears almost esoteric to me, like a guru of that
antenna, "_*The best compact AM antenna in the world - ever!"
*_So it is said that 20 ferrite rods in that arrangement perform 20 dB
better than a single rod. OK, but how well performs such a signgle rod?
20 dB is maybe not enough, compared to a well designed single turn loop,
which i have now. My goal is always LF/137, not MF BCD stations or so.
The advantage of the ferrite solution, if sensitivity is sufficient to
be well above the noise on a quiet day, would be to be completely free
in all /p sesions (without a car).
Would it be possible to reasonable simulate that antenna (not an
accurate model but rather an estimation)?
73, Stefan/DK7FC
_*
*_Am 15.08.2011 00:04, schrieb Roelof Bakker:
Hello all,
If you have time to read it all, this might be interesting:
http://www.gmweb2.net/The%20FS%20Loop.htm
or Google for Ferrite Sleeve Loop.
73,
Roelof, pa0rdt
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