Are 5 GHz telephones safe?

I do not see the relevance of the copper skin depth here. Are you talking about the excitation of the what, ions in the brain? I am not sure of that. It's my understand that 10 mm is perhaps enough to change human metabolism for bone healing and that brain cells don't need much current to be provoked. In fact picoamperes might do nicely.

I know in the literature you fellows use there is a lot of talk of Cu skin depth. Is copper the culprit with electromagnetism radiation then? It's interesting but what has this to do with the power law I was referring to? I was not referring to invasively entering the body.

You are talking about 10mm and I have measured the ELF at 100 meters! So this kind of boggles my poor brain what you are referring to. Aha, 5 GHz is very low invasively then, that is what you are referring to? Most likely. Nothing stops ELF short of nu-metal, Faraday cages, and so on. Okay, we are talking at cross purposes but the basic equations are the same, fine.

Thanks, I was worried.

I was what, glad to read that it is the same stuff. This is what I suspected but I have only personally played with, tested, and messed around with mostly 60 Hz electromagnetic radiation.

I have used the simple power law of 1/r or 1/r[2]squared or 1/r[3]cubed.

It works. I have also seen that taking two lines I can cancel out the radiation to a large degree because the phase of the waves do cancel each other out. You know, the right hand rule in physics. High school stuff.

This is not trivial and not what the resident experts and geniuses say BUT IT IS WHAT THE INDUSTRY HAS DONE TO MINIMIZE THE PROBLEM.

What industry?

Try electric blankets which no longer radiate as they used to. How? They placed the wires together. It's so simple and safe and effective. They were ELF generators placed right up against the body. Not a good idea. And extraordinarily simple to completely well almost completely solve a problem even if there was not a problem. I forget now. Pregnancies were one of the first indications. Not getting pregnant, although you all could joke about that, but miscarriages.

Try schools where the children were getting headaches. An engineer comes in and balances the fields by making sure the neutrals are done correctly. This actually happened. Nothing complicated. Someone had separated the wires in the walls unnecessarily when building the school. Just a case history that always stuck in my memory. An electrician actually, not an engineer, just balanced the neutrals, not even knowing any of this stuff.

And another thing that is not so funny are the blood disorders on those who work on high power lines. Yes, electrocution is the first job danger. But the second are the medical issues which Washington State once studied in detail, yes? You all should know about that.

I do not see why Maxwell has to be brought in here, but if you can direct me to a source, then fine. It's a simple power law.

I don't see what the fuss is about except what? Solutions should be as simple as they can be until they are not correct.

ELF and what you all are discussing may follow the same laws, but the health problems are quite different since ELF penetrates. I guess we were talking at cross purposes.

As Roger Penrose pointed out, it's amazing that humans ever understand anything anyone else says, especially when I chime in :)

Thanks for the reply. I have to be careful here or someone will suggest I am denigrating you. I am not.

Are we talking at cross purposes here? You are referring to 5 GHz radiations, which is the subject of this thread, yes? I was talking about the ELF which started all this decades ago. You remember that really good fellow who prevented the USA from wiring up the state of Wisconsin with ELF to detect whatever perceived threats from the old USSR? And they destroyed his career. He wrote the seminal, to me anyways, books, The Body Electric? He was working for the VA here [veterans administration] and they took away his lab. The early work was on magnetism and healing of bones which has become standard in the medical industry, just as an aside. Not quackery. Really works to heal bones that cannot be healed or are not knitting together as they should.

The power law works wonderfully with ELF since it's so powerful and extremely difficult to contain. It goes through everything, believe me, unless you live in a Faraday cage.

Well, mu-metal or whatever it's called can stop it but that's way too expensive. I would use balancing the wires act [which works for ELF {extremely low frequency}] or graphite sprays or anything because it's a terrible, terrible problem when dealing with delicate equipment for medical purposes as I was doing.

I don't have the tools or knowledge to start measuring 5 GHz so I'll leave that to you. What you said makes sense for 5 GHz except for that fellow who fell into the microwave radiation dish as a practical joke and was about to, well, take apart his fellow soldier who turned it on when he fell into it. I can assure you that the GHz radiation can boil your blood at those levels. It's a bad pun but maybe not a pun.

I'm always out of line but I was not denigrating Mr. Woodgate. I was just bringing up the place where what he said was not true. We were talking at cross purposes. I may be full of smoke. I'll let you know when I peak in a mirror.

Now what you said above is not quite accurate.

Although I used terms that come from magnetism, like Gauss and Tesla, I was referring to radiation, but a specific type of radiation and IT IS RADIATION. But electromagnetic radiation. So stop denigrating my type of radiation and I'll stop denigrating whoever you designate as the non-denigrator.

Whether a magnetometer is a field strength meter, I'll leave for you to figure out. I think you are wrong here too. Why? The meter I was using only worked in 60 Hz fields because it was built only to detect ELF which is Extremely Low Frequency radiation, which is a health problem. So for me it's a field strength meter, literally, but you don't like electromagnetic fields that pulsate at 60 Hz. They don't exist for you? What a snob!

Now regular magnetism, call it DC as opposed to AC which is ELF, is what you are referring to above.

I don't see the difference between an ELF meter, and here comes the joke and the whatever field strength meter you mentioned above. Just different fields, yes? I was jabbering about 50 or 60 Hz fields and you all are going on and on about 5 GHz fields. Mine come from electromagnetism. I don't know where yours come from. Mine are oblivous to most obstructions. Yours are not. It's in the same ballpark. And once you're into medical questions, then well, we'll see.

Personally I don't use a cellular phone except at the most for one hour per month, because that's all I paid for ;) under the university's contract. Hard to believe that I got out of kindergarten, right?

So you owe me an apology for denigrating me, harumph, take that you blazing hypocrite :)

bringing up the place

What he said is not true for "ALL" and that's what I was bitching about. It's not true for ELF which does follow the simple power law because ELF follows anything. You can't stop ELF. It's like the current administration. What a great pun, if I may say so.

So I stand behind my original assertion.

Let me give you an anecdote. Mr. Woodgate is a revered fellow. So is Albert Einstein, so here this goes:

One time Wolfgang Pauli went to the blackboard and said: "What Einstein says is not so stupid..."

What that has to do with the power law is well empowering :)

Like what? Clue me in, that's why I post to the internet.

What's the different between my measuring the milliGauss of an ELF field and whatever you measure with your field strength meters?

Are you sure it's not the same thing, just a different frequency?

I am measuring the 60 Hz field in terms of magnetism because that is what the meter converts it to but it is a field measurement. I am really measuring the 60 Hz emanations, discharges, effusions, et cetera. I am calling it milliGauss because that is what the meter says but it's really measuring the 60 Hz field.

Now what does your field meter measure and how? I could look this up on the internet but forgive me. It's snowed out and I have to go and make track in the snow.

Chew on that while you think up more aspersions to cast upon me.

If I'm wrong, then give it to me logically. You're using ad hominem arguments. That won't work with me. Whoever said I was human?

transmission

a badly designed "tumour cord" (as I heard a yuppy refer to it once) can actually make the problem worse - ie more radiation delivered to head than by holding cellphone there.

1MVA+ =?= 1 million+ volt-amps? how big is that as a transformer? 2 meters? just asking. thanks for the explanation. explains why 250 mA can kill and will skim across the body, if i understood you correctly? well, it shorts out the heart's rhythms but i wondered why it skimmed across the body if one was not careful, and across the heart is a big no-no.

wonderful, wonderful, where were you when i had this problem:

measuring brain waves, let's say, mostly around 10 Hz, really 6 to around 20 Hz

the wires at the time are not shielded, for various reasons at that time the wires are about 2 meters in length the wires are stranded and thin and again, not shielded

how many twists would you have suggested based on what you wrote above?

the current is probably picoamperes and the volts are maybe 10 millionths of 1 volt i was measuring only volts, really, microvolts and also computing frequencies and phase angle octants with discrete FFTs

i just twisted the wires as comfortable as i could, around 1 twist every couple inches or so? i would braid the wires as i used to braid things like a child, must be still a child for i found this very easy to do if there were only 3 wires

now if there were over 24 wires, we have a problem but that's for another post then we might need a thicker, shielded-grounded cable conduit

the simple case, 1 signal wire, 1 reference, 1 ground for the 3 wires of 2 meters in length, braided

but what would have been ideal to get rid of 60 Hz noise? how many twists in 2 meters would you reckon? it was a problem. we had filters and filters but what a PITA.

problems are quite

Recent work too? I recall first reading about this when Wertheimer and Leeper first published their stuff which caused a wild reaction. She was a student of Becker, the fellow who lost his lab because he kept the USA Department of Navy from wiring up Wisconsin with ELF, presumably to look for USSR missiles and stuff. Becker wrote _The Body Electric_ I mentioned previously.

I think some fellows in Italy did the very first lab experiment showing ELF could affect human cells.

But when I read the actual studies, it seemed so small. Granted that you could double the rates of leukemia if you lived within 200 meters of 128,000 KVA or more wires, that is, within a 2+ mG field, but that was from 2 to 4 cases per 100,000. That just did not get me all worked up. Too bad. The headlines were terrific and the response, awful, just full of rhetoric and counter-rhetoric!

Even if statistically significant, practically it did not seem especially powerful. Now if it made you depressed, well, those who have to live near high-powered lines might be depressed as though who have to live near railroad tracks. In any case, I moved away from high-powered milliGauss fields but I became more depressed! Maybe it was self-medicating.

Gets complicated, yes?

anything anyone else says,

getting a cold? snort ;)

Microwaves operate at 2.4 or so GHz. 2.4 GHz is a popular frequency for cordless phones. Other popular frequencies for cordless phones range from a bit under a GHz to a few GHz but less than 10. Some may be only a few hundred MHz.

- Don Klipstein ( snipped-for-privacy@misty.com)

And lets not forget that most real materials are inhomogeneous and anisotropic. Why do you think FEA is so widely applied in electromagnetics? because, when considering anything other than geometrically well conditioned systems (eg toroid), this stuff gets seriously complex. Alas the authors of textbooks often deliberately pick such technical "straw men" to demonstrate how "easy" it is to solve Maxwells equations, thus leading the gullible to the erroneous conclusion its all easy stuff.

It is also interesting that you firstly asked for:

when of course its all just Maxwells equations. Perhaps some basic electromagnetism texts would be a good start. And pretty much all of the so-called "high frequency stuff" is the *same* as the low-frequency stuff - its just that Cu skin depth is around 10mm at 50/60Hz (which is one of the reasons that AC line voltages increase as power levels go up)

Cheers Terry (neither drunk nor trolling)

about the excitation of

mm is perhaps enough

much current to be

the relevance is simply this: electromagnetic theory holds for *ALL* frequencies, big and small.

depth. Is copper the

this to do with the

body.

no, skin effect is a manifestation of electromagnetism. When AC current flows in a conductor it generates a magnetic field. This magnetic field cuts through the conductor, affecting the conductors impedance (ie current is *not* distributed evenly throughout the conductor, but is concentrated at the surface. The skin depth d is the depth into the surface at which current density has fallen to 1/e ie 37% (just like an RC time constant). By the time the conductor radius is > 5*d, *all* of the current flows in that 5*d worth of material - none flows in the inner bit. high frequency coax is sually built with a hollow center conductor, for this reason. And skin depth is a function of material resistivity & permeability, and frequency.

For Cu d = 66mm/sqrt(frequency)

Unfortunately much 50/60Hz design work is done by ignoring these so-called high frequency effects. They are still there, but the low frequency requires correspondingly large dimensions before it becomes significant. Its often ignorable in small transformers, but by the time you get to 1MVA+ its important all right.

kind of boggles my

that is what you are

and so on. Okay, we

exactly.

depends how close you look. If the wires are infinitely thin, and occupy the exact same space, then cancellation is perfect. But of course they are not, so it isnt.

As the voltage increases, a host of other effects come into play which maximise the allowable distance between conductors, which of course screws up this cancellation.

Another trick is to twist the wires together. The EM field is directional, so a pair of conductors carrying equal and opposite currents, with two twists, generates two fields, of opposite direction, with a center-to-center spacing that of the twists. If this "twist pitch" is very small compared to a wavelength (which at 50Hz is several

1000km) then the two opposing fields pretty much cancel each other out.

completely solve a problem

first indications. Not

done correctly.

in the walls

in my memory. An

knowing any of this

work on high power

medical issues which

to a source, then

in a trivial case yes. As others have mentioned though, it can get a lot more complex depending on the adjacent materials & geometries.

as they can be until

problems are quite

There has been some interesting work on the effects of low power EM radiation on proteins and DNA.

anything anyone else says,

Cheers Terry

yep

not very. perhaps 1.5m x 1.5m x 1.5m

the body, if i

wondered why it skimmed

thats pretty much it (he says, well outside his area of understanding. still, never let that stop me before...)

the tighter the twist, the better the cancellation. BUT inter-wire capacitance goes up, as does cable length and hence resistivity. most cables require a bend radius about 10x cable diameter to prevent insulation creep & hence degradation/failure. look at a piece of CAT5 - about one twist per centimetre for 10mbps/100mbps.

volt

couple inches or so?

a child for i found

to attenuate 50/60Hz (differential mode) this would be just fine. dont forget common-mode noise though.

meters in length,

meters would you

I invariably use CAT5 cable, its cheap and comes pre-twisted. STP is real handy stuff...

problems are quite

first published their

who lost his lab

presumably to look

previously.

I recall reading a few years back (New Scientist IIRC) about an experiment showing proteins lining up under the influence of an EM field. ditto with gene expression. Mostly I think it shows that the "heating is the problem, not enough energy = no problem" argument is no longer valid.

could affect human

double the rates of

within a 2+ mG

all worked up. Too bad.

counter-rhetoric!

these are trivial compared to a recent study on the leukemia rates of children living near gas stations - 11x to 15x or so.

years ago a buddy of mine was in the NZ army engineering corps, and led a study on the health effects of radar installations. They went through the medical records of all NZ soldiers, and found no correlations at all. They also found no 65 year old armourers, and painters didnt make it past 70. Conclusion: bugger EM fields, stay the hell away from nasty chemicals.

powerful. Now if it made

depressed as though

high-powered milliGauss

anything anyone else

no, a gram of coke

Cheers Terry

Information from the IEC:

The new International Standard IEC 62209-1 was developed jointly by the IEC, by the European Committee for Electrotechnical Standardization (CENELEC) and by the IEEE, who worked together informally through common membership in various technical committees. This is the first of a multi-part series of standards and it covers devices, such as mobile phones, with a frequency range of 300 MHz to 3 GHz.

This is about measuring SAR by a method compatible with both European and US exposure provisions.

--
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk