Hello Stefan and Wolf!
I used to try single-loop antenna some years ago. It worked well.
73!
Lubos, OK2BVG
________________________________________
Od: [email protected] <[email protected]> za
uživatele Wolfgang Büscher <[email protected]>
Odesláno: 27. dubna 2016 19:11
Komu: [email protected]
Předmět: Re: VLF: A single turn RX loop for VLF
Hello all,
I can confirm such a single-turn loop with a big ferrite transformer
works well - even with a very simple amplifier.
Construction details and a few spectrograms at :
http://www.qsl.net/dl4yhf/vlf_rdf/vlf_single_turn_loop.htm
(this 'ferrite cylinder' can frequently be seen at hamfests, but none of
the dealers could tell who actually made them, and what their original
purpose was..)
Cheers,
Wolf .
Am 27.04.2016 um 18:31 schrieb DK7FC:
> Hi VLF,
>
> Today i've installed a second loop into the tree. It is a simple
> copper tube having 10 mm diameter and about 4m length.
> https://dl.dropboxusercontent.com/u/19882028/VLF/20160427_084708.jpg
> The loop is not resonated. The ends are just hold together with a screw.
> https://dl.dropboxusercontent.com/u/19882028/VLF/20160427_092012.jpg
> It is a very stable / robust construction which needs no further
> elements to hold it into the tree.
> The screw is protected against rain with some bonding tape. Before the
> mounting, a ferrite transformer with Al ~ 6000 nH was put on the tube.
> First i tried 20 secondary turns.
> https://dl.dropboxusercontent.com/u/19882028/VLF/20160427_092420.jpg
> Later i choose 40 turns and finally 80 turns.
> The results between the N-S loop and the E-W loop are still visible at
> http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
> DHO38 is much weaker, the Alphas are much stronger, HWU is stronger.
>
> All in all it appears that this loop performs better then my 80 turn
> hula hup circle loop (0.8m diameter). And by using the transformer it
> can be adapted optimally to the preamp input impedance. It even works
> down to 100 Hz, with limited performance of course.
>
> I'm now looking forward to receive something from the East or West. Is
> there someone out there ready to radiate a signal?
> Also, a VLF RDF grabber would be fine, maybe even by using idenetical
> antennas (to be built).
>
> 73, Stefan
>
> PS:
> BEWARE: This is not new! Someone has done it before, maybe even in the
> 1920s. VLF receptions on the Dreamers Band were done with such a loop
> for example by F5WK
> (http://f5wk.blogspot.de/2010/09/antenne-loop-vlf.html).
>
Single-loop_scheme.JPG
Description: Single-loop_scheme.JPG
|
