MOBIUS cross loop antenna
#1
Hi all
I`m a new participant and I had running the system blue, first with two 200mm indoor rod ferrite antenna, that later I changed to MOBIUS cross loop. The system seems working very well with ferrite antennas, but it pickup strong noise from switching power supply in my house and Neighbors (I live in an apartment), especially from cell phone chargers. So I build a cross MOBIUS loop with coaxial cable HELIAX 3/8", with PL 259 connectores, and respective SO panel connector. I used a square metal box for coaxial connectors, that shunt all shields in the point oposite to the inverter connections of the coaxial cable. I had run this antenna for some days, and it working great, with much lower noise and more directivity that give the possibility of optimizing the noise floor. With this "shield shunted" MOBIUS cross loop I was able to detect lightning at 6600Km. I read about MOBIUS and I always saw that the shields were not interconnected. So, I decided buil a new "shield isolated" MOBIUS cross loop and test again. I was desapointed, because the noise go up and the directivity drop. I tested this "isolated loops" by a pair of days, and the detection drop a lot. Again, I returned to the "Shield shunted" cross loop, and the detections ratio was go up again. I use a gray color toroid transformer with 50 turns of 0.25 isolated wire.  Has someone  done other tests with MOBIUS cross loop?
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#2
Made my first Mobius Loop Antenna a week ago.

It consists of 4 turns of RG6 Quad Shield Coax, (Just because it was readily available).
600mm in diameter & mounted in 65mm PVC pipe.
Not finished yet; need to shorten the leads & move it to it's final location.

Would be interested in feedback & in particular whether adding  transformers will be of benefit.
(Have some toroids on order).

Would also like to know what the major difference in it being a Mobius loop, Vs just a plain coax loop is,
considering it's only whether it's joined at the centre or not, (and the shield connected).

Obviously my first attempt & know there's still a lot to be learnt.

Thanks

Phil.
 
   
Stations: 1928
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#3
(2017-08-03, 01:32)Phil23 Wrote: ... Would be interested ... in particular whether adding  transformers will be of benefit.

Would also like to know what the major difference in it being a Mobius loop, Vs just a plain coax loop is,
considering it's only whether it's joined at the centre or not, (and the shield connected)....

I would too!  Smile

Also, the difference between different coax loops and ferrite antennas. From what I've read here --and what I have seen on many BT stats pages-- there is absolutely some benefit of using large coax loops vs. ferrite antennas.

Here are some of the many stations running non-ferrite H-field antennas made from coax, etc. 
  • 1199 Waterville, Ohio. This is one of the very best stations in Region 3!
  • 1112 Springfield. He just solved his noise issue this evening, and almost immediately surpassed everyone on this list and on this other one.
  • 658 Kingsport 
  • 1943 Cedar Park 
There are others (some not in Region 3), that I couldn't find just now. And over time, I see some of them consistently outperforming many other nearby stations that use ferrite loops.

Of course, it goes without saying that being in a quiet location, as well as where the thunderstorms are, matter a lot. But I have taken all those things into account.

I am seriously considering building three loops like the one below, to replace the 4-turn unshielded 1m diamond wire loops here. (I will use RG-11, since I have a 1000' spool of it.)

But should I build a different loop with a transformer ("trafo") instead? Might it be superior? @Richo in his post at https://forum.blitzortung.org/showthread...0#pid12970 seems to imply this.

   
Regards,
Mike
Station information
Stations: 1977
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