Author Topic: What about a magnetic loop for stealth and emergency communication?  (Read 10374 times)

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Captain Crunch

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I've been looking around for awhile to see what is available concerning magnetic loop antennas. I've found a lot of flimsy stuff and a crap load of junk. But today I've found the following:

http://chameleonantenna.com/PORTABLE%20ANTENNA/CHA%20M-LOOP/Chameleon%20M-LOOP.html

It looks amazing!!

CC

Tempstar

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #1 on: October 06, 2014, 03:48:12 AM »
Hi Captain,
 I have a 20 meter magloop from bluecollarants.com. I bought serial #1 to evaluate it, and found it works as advertised. By that I mean it will kill electrical noise which is what I was seeking for SSTV. Would I use a magloop for EMCOMM? No. While it is great for pulling noise from a decent signal, it has no magical receive properties and even less magic for transmitting. Add the fact that you need one for each band to be super efficient.  The best product I have found from Chameleon is the Hybrid with a V1L and the MIL whip. This is my travel setup and goes up quick, but with anything easy there are drawbacks, and anytime a matching transformer and network are used there are losses to contend with. Carl at Chameleon does some amazing things, but at the end of the day they are still compromise antennas.
"Preparedness is a lot more than just buying stuff"

Tevin

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #2 on: October 06, 2014, 07:44:45 PM »
I've been looking around for awhile to see what is available concerning magnetic loop antennas. I've found a lot of flimsy stuff and a crap load of junk. But today I've found the following:

http://chameleonantenna.com/PORTABLE%20ANTENNA/CHA%20M-LOOP/Chameleon%20M-LOOP.html

It looks amazing!!

CC

I'm always skeptical of new & amazing antennas that would look small on a Smart Car and claim to work on every band and outperform 100 year old proven designs. Almost all of them work to a degree but I've never seen or heard of one that truly delivers on all its bragging.

I have a buddy who once had a similar loop antenna...and this was 30+ years ago. I think it was a Butternut product. He referred to it as "a dummy load on a mast."

The link does not give a price; I bet it'll be over $300. And if that 35/65 watt power limit is for real, it better have one mofo sweet SWR. And it needs to be  a genuine straight radio-to-antenna SWR, not a run-it-through-some-coils-and-lie-to-the-transmitter SWR. I won't be fooled by a glorified antenna tuner. 

This one may indeed be the magic bullet antenna. But over the years I've seen enough gimmicks not to get excited.

We'll see how it goes. Or doesn't.
« Last Edit: October 06, 2014, 07:53:04 PM by Tevin »

spacecase0

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #3 on: October 06, 2014, 11:23:31 PM »
one of my friends has built 2 of these
http://www.hlmagneticloopantennas.com/
he showed it to me, and they work amazingly well

Captain Crunch

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #4 on: October 08, 2014, 12:31:26 PM »
I'm always skeptical of new & amazing antennas that would look small on a Smart Car and claim to work on every band and outperform 100 year old proven designs. Almost all of them work to a degree but I've never seen or heard of one that truly delivers on all its bragging.

I have a buddy who once had a similar loop antenna...and this was 30+ years ago. I think it was a Butternut product. He referred to it as "a dummy load on a mast."

The link does not give a price; I bet it'll be over $300. And if that 35/65 watt power limit is for real, it better have one mofo sweet SWR. And it needs to be  a genuine straight radio-to-antenna SWR, not a run-it-through-some-coils-and-lie-to-the-transmitter SWR. I won't be fooled by a glorified antenna tuner. 

This one may indeed be the magic bullet antenna. But over the years I've seen enough gimmicks not to get excited.

We'll see how it goes. Or doesn't.

Wow!! That's a great attitude to have toward new stuff and people trying to innovate!
Have you read about their M-LOOP?

I'm following them on their Google + page. I don't know how to link a Google + page but search for Chameleon Antenna. You can use the M-LOOP with the basic 36" loop and they'll also offer a telescopic square loop of 45" long. You can also use various lengths of wire to create larger loops like 20' or 25' in diameter or maybe larger for 160M. It's pretty neat!

Do you really think that they'll sell that for under $300?
Have you seen it? The amount of work is astronomical. I haven't seen something like that on the market yet!
This thing plug directly into the rig and nothing else!

If you can buy an Alex Loop for more than $350 USD (http://www.hamradio.com/detail.cfm?pid=H0-012701#results) which is something that is very light built or a MFJ Loop at $500 (http://www.mfjenterprises.com/Product.php?productid=MFJ-1788) I think that it is going to be more than that.

Tevin

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #5 on: October 08, 2014, 06:27:11 PM »
I've had my ticket for over thirty years and "Magic Antennas" have been around much longer than that. I'm all for innovation but those pesky laws of physics keep getting in the way. There is only so much you can squeeze out of an aluminum hula hoop and a box of coils.

Long ago when I lived in a small one bedroom apartment I made a loop antenna from plans in an ARRL book. It worked OK. Not great, but OK. And I sure as hell didn't pay hundreds of dollars for it. Nobody uses, as Tempstar very accurately observes, compromise antennas when they have other options.

These products are always a last resort, never a first choice. When an antenna's biggest selling point is its size and not its performance as an antenna, then it's a tipoff you are looking at a gimmick, especially at the prices theses things go for.

Anyway, I'm not looking to be argumentative, I just want to point out that loop antennas have been around for decades and there is nothing amazing or "innovative" about them. YMMV. Everyone's gotta do what they think will work best for them. 



« Last Edit: October 08, 2014, 09:14:24 PM by Tevin »

Lamewolf

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #6 on: October 15, 2014, 03:20:42 PM »
I've been building and experimenting with magloops for a few years now and I have to say I am impressed with their performance for such a s mall size !  In fact, after I showed my 15 thru 40 meter magloop to a friend, he built one and was working DX with it hanging from the rafters of his basement workshop - yes, the loop was basically underground and he was running 10 watts from an old Yaesu FT-7 on 20 meters.  Southern Ohio to Croatia, Hungary, and a few other countries running 10 watts from a 3 foot loop is impressive !

spacecase0

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #7 on: October 15, 2014, 09:00:00 PM »
the big advantage I have seen with the magnetic loops is that the bandwidth is so narrow that you get almost no noise,
so perfect if you live in a space with many other people close by that all have CFL lights and noisy computer hardware
« Last Edit: October 15, 2014, 09:01:31 PM by spacecase0 »

Captain Crunch

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #8 on: October 24, 2014, 06:05:32 PM »
Magnetic loops, when considering size vs power used, are excellent performers! I've built several of them already. They aren't hard to build but you need to be precise and meticulous about how you build them.

The most easy to build is the inductive loop made with a faraday coupling loop. They work great but are usually limited at about 10W to 20W. The other type of magnetic loop do not uses a faraday coupling loop but multiple capacitors instead. I've read somewhere that they can cost about $14K each like the Elbit antenna system:

http://www.elbitsystems-us.com/sites/default/files/imported/c4i/Communication_Solutions/Micom/Micom_Tactical_Antennas_ESA_4_11.pdf

I would love to have one like this one for about $600 USD:






Or this one here from an European manufacturer but the cost........... $1500 USD OUCH!



MFJ is manufacturing some magnetic loops too but I do not trust MFJ products. The MFJ manufacturing quality is worse and you would need to buy two antennas to cover only 10M to 40M.

CC

spacecase0

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #9 on: October 24, 2014, 08:44:27 PM »
magnetic loops will cost you a bit if they are done correct,
the current gets quite high in them, so you need big solid connections,
and the capacitor needs to be very low loss and high current and high voltage rated,
it by itself will cost 350 to 400 $ if you get one cheep, like out of russia,
(the russian vacuum capacitors are quite nice)
and the capacitor should be remotely adjustable if you are to have any hope of using it.
doing it all yourself as low price as you can is still going to be about 600 $

the MFJ ones are not very efficient due to the capacitor and connection limits.

Lamewolf

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #10 on: October 27, 2014, 11:35:46 AM »
magnetic loops will cost you a bit if they are done correct,
the current gets quite high in them, so you need big solid connections,
and the capacitor needs to be very low loss and high current and high voltage rated,
it by itself will cost 350 to 400 $ if you get one cheep, like out of russia,
(the russian vacuum capacitors are quite nice)
and the capacitor should be remotely adjustable if you are to have any hope of using it.
doing it all yourself as low price as you can is still going to be about 600 $

the MFJ ones are not very efficient due to the capacitor and connection limits.

Does this mean that the DX I've worked at 5 watts with my $20 homebrew magloop doesn't count ? :-[  DRATS !

spacecase0

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #11 on: October 27, 2014, 02:01:26 PM »
Does this mean that the DX I've worked at 5 watts with my $20 homebrew magloop doesn't count ? :-[  DRATS !
it counts,
just means that if you have 300W out and you want to talk on the days where band conditions are horrible,
it costs way more to keep up with or exceed what wire antennas do.

Lamewolf

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #12 on: October 27, 2014, 03:23:34 PM »
Well, I know what you are saying, but I do have a wire antenna - a 40 meter extended double zepp that is 178' long and fed in the center with 450 ohm window line and a tuner for 10 thru 160 meter operation.  And I have compared it on good and bad days with the magloop antennas I have built and while the zepp did outperform it in some cases, the difference was not a big difference.  In fact, on the magloop I could hear some of the weaker stations better due to its narrow bandwidth which causes it to be much quieter than the zepp.  On the other end folks were hearing about an S unit less than they were on zepp.  And to top it off, the comparisons were made with the magloop sitting on a tripod about 3' off the ground and the zepp is 35' at the center with the ends at 20'.  If I had the loop up at the same level as the zepp, I would bet that the difference would have been even less.  So, for a person that is not able to put up wire antennas, a magloop would be a great option for them as they do work and they do work quite well.  Give me a good hunk of wire any day but my magloops are mainly for portable operation anyway.

spacecase0

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #13 on: October 27, 2014, 08:29:33 PM »
if ti matters any
I have tried the magloops 4 foot over the ground, and up off the ground quite a bit more,
and as long as they don't have anything in the way (like a tree) they seem to work pretty much the same regardless of elevation

Lamewolf

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Re: What about a magnetic loop for stealth and emergency communication?
« Reply #14 on: October 29, 2014, 06:15:26 AM »
if ti matters any
I have tried the magloops 4 foot over the ground, and up off the ground quite a bit more,
and as long as they don't have anything in the way (like a tree) they seem to work pretty much the same regardless of elevation

Yeah, I agree.  Some folks say they work better up higher but I haven't seen much difference either way.  But that's why I like them for portable use.  Just set them on a camera tripod and start operating.