Magnets attracting wireless attention

"Magnets are beginning to gain the attention of home-electronics manufacturers and government agencies as an alternative to Bluetooth and other short-range wireless techniques."


CNET Article

Cool stuff,
Mike

Hmmm, sounded more like an April 1st article, but I suppose it would work /ubbthreads/images/graemlins/smile.gif And, best of all, your cellphone can be stuck to the fridge when not in use...

Actually, it sounds very sophisticated based on what I've read. Short distance ~4 ft., very long battery life, much more secure than RF due to limited range. In Steve Jobs' parlance, "Think whisper."

But...

"Magnetic fields also create waves, but the waves form a kind of bubble, which stops growing after four feet, making them more secure than waves wafting endlessly in every direction, Cui said." (quote from that same CNet article)

What concept in the land of physics could that word "bubble" be referring to which limits the influence to negligable after a given distance?

Maybe I'm missing something here, but I've tried very hard to keep any and all magnetic fields from coming anywhere near my computer stuff. There are just so many bad things that can come from stray magnetic fields.

For one, your hard drive is so very sensitive to magnetic fields that it's been proven that even the Earth's magnetic field is enough to corrupt data stored on a hard drive if left idle for years in one spot (as in being stored on a shelf). They recommend that if you store a hard drive on a shelf for any extended period of time that you rotate the orientation of the drive about every 6 months in order to help keep this from happening.

Another thing that is adversely affected by magnetic fields is your CRT monitor (Non-LCD). I used to work in TV repair and have actually seen CRTs damaged by being exposed to a strong magnet. In less severe cases, they can usually be saved by being demagnetized, but I've seen some that were totally ruined by it. In really old televisions I've even seen the CRT be damaged by poorly magnetically shielded magnets in the TV's own built-in speakers.

Then there is all of the old media that is stored using magnetism such as audio cassette tapes, video tapes, floppy disk, backup tapes, zip disk, etc.

Even if they tried to convince me that this technology is safe, I would still avoid it in preference to something that I already know is perfectly safe to have around all of my electronic stuff. Maybe I'm more than just a bit paranoid, but that paranoia has saved me a lot of money and trouble over the years.

X-CalBR8,

Here is a link from Dans Data regarding magnets around computers, it's an interesting read.

Unconventional Wisdom

Mike

"What concept in the land of physics could that word "bubble" be referring to which limits the influence to negligable after a given distance?"

It seems to be referring to the way that magnetic flux works. Just take a lot of iron filings, put them on a piece of paper and then put a magnet under the paper and you can get a visual representation of the way that the lines of magnetic flux travel. This is such a common demonstration in Physics that I'm sure a Google search would turn up a picture of this phenomenon. Just do a search for "magnetic flux" "iron filings" and you should get some pictures of this experiment.

yam: Well, all I can say is that you can find web sites that say just about anything these days, but I know from first hand experience what I'm talking about because I used to work on the things and I've seen the damage that can be done with magnetic fields.

Right now I have an audio cassette tape sitting on my computer desk that was ruined by an average run-of-the-mill low gauss magnet getting near it. It wasn't even one of the much more powerful rare-earth magnets.

I also have a friend that has a picture tube that was ruined by his kids playing with magnets in front of it.

I even knew of a guy that nearly ruined his monitor by having a common household fan running near it. You could see the magnetic flux coming in on the monitor (looked like a rainbow effect). Lucky for him, the monitor's built in deguasser was enough to restore his monitor back to normal, but if the fan had been a little closer for a little longer before we noticed it, he might not have been so fortunate.

I guess it's just like anything, you can either take a chance or you can play it safe, but at least you now know that you are indeed taking a chance if you put strong magnetic fields anywhere near your computer stuff. Believe me, this is no urban myth no matter what others may claim to the contrary.

While it's true that there is quite a bit of bogus information on the Internet, Dan's Data is pretty well regarded.

I worked in research at the University of Washington for about 11 years, then in IT for another nearly 5 years. Although we did have one guy mess up a monitor by getting over zealous with a magnet I have never witnessed firsthand any problems because of small magnets being in the vicinity of a computer. Now tapes and floppies would obviously be a different matter.
Anyhow, while in research and IT many of us used refrigerator magnets on our towers with no problems. In fact some of the guys used old hard drive magnets and never had problems. Though old hard drive magnets are much more powerful than your run of the mill "Got Milk" refigerator magnets.....I didn't use them.
As far as networking with a magnetic field is concerned. I would say in my most humble of opinions that it is not very powerful. I would also speculate that there are much more powerful magnetic fields around us right now than what will be produced by these new gadgets.

In any case, nice debate, that's what it's all about here. It's all theory til it works anyhow. If it causes problems they will certainly have hell to pay!

Now....I'll have to dig up the links about providing broadband Internet access via the power grid. They have had home electrical outlet networks for awhile now. I would love to see another option for broadband where I live.


/ubbthreads/images/graemlins/smile.gif
Mike

Except that power line networking will put an end to ham radio operation as it uses much of the same bandwidth and radiates out of those non-shielded wires like crazy. Somewhere on the internet there is video of a ham driving around a test neighborhood and dialing his receiver and all you can hear all the way up and down is noise. We all need to be awash in even more RF...

I haven't been convinced that it's a good idea yet.

Although I'd also love to see options for broadband. Right now my choices are the phone company or the cable company, neither one is really known for great customer service /ubbthreads/images/graemlins/smile.gif

My prediction is that if the electric company wants to offer it they will have to bring in some really crack customer service consultants from the DMV to run their call center /ubbthreads/images/graemlins/icon15.gif /ubbthreads/images/graemlins/grin.gif

James S

Yea I agree with your comments on RFI. The FCC regularly fines cable TV service providers for unterminated cables and RFI. Internet over powerlines will be a nightmare for us hams.

GregR, KC6ZWO

Broadband over power lines...new thread here.

mike

I can't let this go. I guess if I had some time I'd research it, but for now I'll just state my objection to this concept of space-limited influence of the magnetic field... (My apologies to Gauss, Maxwell, and many others for my poor memory)

Point 1.
If you vary a current, then you get a corresponding induction of magnetic field. The converse is also true. E&M are intertwined as long as one is variant. As a result, a varying magnetic field is electrically detectable. (And if it's a very small amplitude, then its detection only requires more sophisticated electronics. Thus, 4ft limit is BS.)

Point 2.
If you look carefully at the 2-D image of a magnetic field, say you're remembering what those iron filing experiments look like, then you'll notice that the field does not die off at any point. It drops very quickly yes, and approaching the poles there is lots of dissipation. However, nowhere around the magnet is the field nonexistent. Thus, the "bubble" blather still sounds like marketing BS.

Someone please correct me...

Careful with those magnets; there is some evidence that they can affect brainwaves and other physiological processes. There's already too much EMR. Try detuning a portable headphone AM radio and walk around any urban environment. It will be a revelation (and a pretty good storm predictor). A vacant FM channel might hold some surprises also.

Brightnorm

Not to worry Brightnorm, I wear one of these.... AFDB

/ubbthreads/images/graemlins/grin.gif

Mike

yam: Yeah, but we need something stronger that that these days. The standard tin foil hat just doesn't cut it anymore. I mean, that's only aluminum after all, it won't even block all of these magnetic waves that we've been talking about.

I think it's time to take the tin foil hat to a whole new level! What about the ever growing threat of mind control through magnets? I think it's time to rethink my whole anti-mind control strategy now. To think, all of this time I thought that I was perfectly protected with my now, obsolete, 2-ply tin foil hat. /ubbthreads/images/graemlins/grin.gif

The 4ft bubble is kinda BS, but not totally. The fact is that the intensity of a magnetic field does fall off rapidly with distance. The intensity of radio waves, like light and gravity, follows an inverse square law. The strength of a magnetic dipole follows an inverse cube law.

So, if you move from 1 foot away to 4 feet away from a signal source, a radio signal would be weaker by a factor of 16, but a magnetic signal would be weaker by a factor of 64.