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Date: Mon, 15 Aug 2011 02:16:47 +0200
From: =?UTF-8?B?U3RlZmFuIFNjaMOkZmVy?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Ferrite RX antennas
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Hi Alan,

We'll see. I just bought 16 pcs. 140 mm length and 8 mm diameter ferrite=20
rods for 30 EUR (transport included) on ebay! 16 were available. The mu=20
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=20
antennas for amateur LF! I will compare to conventional antennas.
So i can play with that type of "magic" antenna. Otherwise i could take=20
e.g. 7 psc in parallel and that 2x in series. Should be OK for /p=20
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 fa=
ctor
> A =3D100 in the conventional loop equation....so 20dB ...???????  extra
> ferrite cross sectional area does help too, plus bigger former less tur=
ns
> for the inductance less copper loss, higher Q (also increases the outpu=
t).
> Better but no magic!
>
> For some experimental measurements see a Electonics World article  on L=
oops
> by a couple of Itallian amatuers (app 2004 or 2005). Having said that t=
here
> may be some mileage in not winding the coil direct on the ferrite. Ferr=
ite
> 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 befo=
re.
> Accurate comparative measurements on a reliable signal like DCF39 would=
 be
> much more interesting.
>
> Alan G3NYK
>
>
> ----- Original Message -----
> From: "Stefan Sch=C3=A4fer"<Stefan.Schaefer@iup.uni-heidelberg.de>
> To:<rsgb_lf_group@blacksheep.org>
> Sent: Monday, August 15, 2011 12:08 AM
> Subject: Re: LF: Ferrite RX antennas
>
>
>   =20
>> 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 loo=
p,
>> 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:
>>     =20
>>> 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
>>>       =20
>>     =20
>   =20