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Author Topic: Moebius Loop Antenna?  (Read 8955 times)
N3HKN
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Posts: 113




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« on: February 23, 2011, 06:31:05 AM »

There are some reviews on a loop antenna made on the principal of a Morbius Loop - http://www.eham.net/reviews/detail/9441.

I presently have a "conventional" magnetic loop for 20 meters. It works well. However, its bandwidth is limited even with a motor driven high voltage variable. The mystery of the Moebious Loop is that from the little research I have done there is no need for any tuning capacitor and it allegedly covers LF through 10 meters. The reviews seem to say that you can transmit with it but absolutely no mention if that is 10mw or 1kw power level. So a big question there. There is also no information that I can find that shows the performance over its claimed bandwidth. Does it work well at say 7mhz but is bad at 24mhz?

I understand the Moebius thing about crisscrossing wires as you wrap the wire around a 1m circle. However, I can find no info on wire size or number of turns. I am not excited about dropping $400 for a mystery antenna. I built one of those things during the EH antenna craze. Wasted a box of aluminum foil!

Dick  N3HKN
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N3OX
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Posts: 8847


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« Reply #1 on: February 23, 2011, 07:34:23 AM »

The mystery of the Moebious Loop is that from the little research I have done there is no need for any tuning capacitor and it allegedly covers LF through 10 meters. The reviews seem to say that you can transmit with it

The reviewed version is an active receiving loop.  The reviews don't seem to say you can transmit with it.  They talk about transmitting on other antennas.  
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N3HKN
Member

Posts: 113




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« Reply #2 on: February 23, 2011, 10:05:28 AM »

There remains some ambiguity about transmitting. The product has a separate "key input" on its pre-amp box. This causes a relay to disconnect the pre-amp during transmitting or is it really just to remove the pre-amp if a strong signal is overloading it. I suspect the latter..  I really do not see how it can beat a "standard magnetic loop on receive unless the "Moebius" crisscross wiring offers some advantage. I will pass on this product for now.

Dick N3HKN
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KF7CG
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Posts: 834




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« Reply #3 on: February 23, 2011, 10:47:56 AM »

I don't know what it does for Ham Radio signals but the interesting facts of the loop are:

You must go twice around the loop to get back to your marked starting point.

It only has one side, and only one edge. That is you can go from any point on the loop to a point directly oposite it through the media without having to cross an edge.

A Moebius loop must always have an odd number of half twists or it loses its special features.

KF7CG
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KA5N
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Posts: 4380




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« Reply #4 on: February 24, 2011, 01:25:16 PM »

The twists and turns of a Morbius antenna could soon put me in the arms
of Morpheus.

Allen
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W9CW
Member

Posts: 107




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« Reply #5 on: February 26, 2011, 07:36:26 AM »

It's a receive-only loop antenna with a preamp.  They key sense line shuts down the preamp when you are using a separate transmitting antenna in the near field.

Here's a link to the PDF of the antenna specs.  Note line 2 of the headline "(Receive-Only Antenna)"

http://www.pixelsatradio.com/PDF/RF_PRO-1A_Cut_sheet.pdf

73
Don W9CW
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N6GND
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Posts: 374




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« Reply #6 on: March 01, 2011, 01:35:58 PM »

My sense of the performance of the Moebius loop antenna (from the eham reviews of it and of the Wellbrook loop, and from my own experience in designing receiving loops) is that it performs very well as a small loop (less than 1/10 wavelength). Such antennas can very usefully lower your receiving noise floor.

That said, the benefit of this loop's Moebiosity proper is beyond me.

Transmitting loops are other beasts completely.
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N3LCW
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Posts: 149




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« Reply #7 on: March 02, 2011, 10:10:24 AM »

I found an interesting magnetic loop design for increased bandwidth:

http://www.qsl.net/hb9mtn/hb9mtn_adf_loop.html

I built one for 17M using the capacitive loading technique described above and it did in fact work well with an SWR of less than 1.5:1 across the band.  It can't hurt to try.

Andy
N3LCW
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N6GND
Member

Posts: 374




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« Reply #8 on: March 02, 2011, 03:06:33 PM »

I found an interesting magnetic loop design for increased bandwidth:

http://www.qsl.net/hb9mtn/hb9mtn_adf_loop.html

I built one for 17M using the capacitive loading technique described above and it did in fact work well with an SWR of less than 1.5:1 across the band.  It can't hurt to try.

Andy
N3LCW

Very cool. Thanks for the reference.
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WA2ZKD
Member

Posts: 1




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« Reply #9 on: December 16, 2012, 07:53:23 AM »

for more info on Moebius Loop Antenna, see:

http://www.ece.unm.edu/summa/notes/SSN/note7.pdf
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