Smartcard emitting 13Mhz EM field

[osci]

Hi all,

I need some help and some links into any research that has been done on the safety of these particular smartcards that emit a 13Mhz EM field.

A friend of mine told me that his employer is introducing these smartcards and will be used for staff identification, building access & cumputer access & security.

This is the only information he can give me at this stage but I have asked him for more on what type of card this is or anythng that may help, so I can report back here

He's concerned about any health affects, side affects these EM emitting smartcards may have individually or especially in clusters.

if anyone can give us any links that I can pass onto to him to read up it be much appreciated.

cheers all

[tristen]

I assume that they are passive (not active) devices and respond only when in or near a card reader of some kind.
This being the case, they will not emit any form of radiation until "energised".
I do not think that they will pose any risk, especially at only 12 MHz.

The anti-theft devices attached to clothing in department stores and similar devices placed in books are also passive devices, which respond only when energised in the appropriate electro-magnetic field.

Interesting topic. I must do some more research on such devices to find out what current developments are.

There is some (fairly dated) information at , but not at first glance, specifically concerning the devices you mention.

[ericdog]

Going along with what Tristen has said, *most* building security access systems use a passive device, or "tag", commonly referred to as an RFID device or "proximity card".

The reader (on the wall/door) is the thing that emits an electromagnetic (EM) signal (field), usually at around 100 to 200KHz, this "field" is used to "excite" the RFID access device (tag), the tag then uses this field to power itself where it "responds" with its unique ID number which is then fed by the reader back to a processing system for verification. If the tags code is valid, the processor then grants access and (usually) records the time/date of access.

Smartcards, as such, generally aren't used much now for building access, although, some RFID cards look like white smartcards but have no contact pads on them.

RFID tags are much the same as used in companion animal "micro-chipping" for identification.

There would be no risk of EM radiation exposure from the use of these devices or the reader as the levels of EM emitted are extremely low.

[trash]

13MHz is the RFID standard frequency. I've forgotten the exact frequency, it'll be something I pay a little more attention to in the future.

13MHz is completely harmless especially with the power levels used for RFID.
If you'd like to know the Australian standards for non-ionising exposure etc.
Arpansa is the government organisation responsible.

[ericdog]

The RFID tags that I have been using run at 125KHz.....

From the IDxx PDF data sheet:

The ID-2, ID-12 and ID-20 are readers for the
popular EM4001 format 125KHz tags. Read
ranges of 1-15 cm are possible with ISO cards
(25cm with a well tuned matched antenna on the
ID-2). With CMOS/TTL Serial, Wiegand26 and
NEW with this series..

But I'm sure that other frequencies are used, there are a few different standards..

[osci]

thnaks guys, the bloke hasn't got back to yet about the exact type of card they are, as soon as I do receive info will post here.

cheers

[rob916]

I think I would be more worried about the mains wiring in your house or sleeping with your rf emitting electric blanket on.
Get a gauss mauss and check things out.
I think your employer, by law has to provide an msds on anything in your workplace, but the government will not acknowledge risks from emr, so good luck.
Better buy a few rolls of tinfoil.

[ericdog]

Better buy a few rolls of tinfoil.

That'll keep the aliens away too, if you stick it on your head!

[bulbous]

The employees walk through the tiny RF field at 13MHz and walk up to a taxi transmitting 25W of 500MHz RF through a 4dB gain antenna at face/chest height whilst the taxi driver argues for 30 seconds about his last job....

Magnitudes greater danger !

[porkop]

there are EM fields of all frequencies and guassian densities all around us all day and night, every day. Should we be worries about all them as well??

personally, I stay away from fields of 2.45GHz in the 5 Watt plus level, but you still can not avoid everything.

I once had a customer concerned about the Foxtel cable lead in to her house coming in near her bedroom, I asked is she was also worried about the 240v 50 Hz power lead in also coming in near her bedroom!

[ericdog]

I once had a customer concerned about the Foxtel cable lead in to her house coming in near her bedroom, I asked is she was also worried about the 240v 50 Hz power lead in also coming in near her bedroom!

Back in the 80's, when I was working for a communications company, we had a woman call up because she wanted someone to go and check her place out as she thought she was being "bugged" through her water pipes..

Gees, some people get a little crazy....

I would also avoid things in the 2.45GHz range at 5W+.. That frequency is good for cooking by "exciting" water molecules, so I believe.

[trash]

I would also avoid things in the 2.45GHz range at 5W+.. That frequency is good for cooking by "exciting" water molecules, so I believe.

Still a bit of that old microwave oven myth happening there ED.
it's not just water molecules, it's all molecules
And it's not just 2.45GHz, it's everything from about 1GHz to 5GHz.

Which is the worse of these three to have you head in front of the antenna ?
100W at 2.2GHz, 2.45GHz or 3.0GHz.

Think of it like this, a 9mm Bullet is representative of the 100W power.
The frequency is representative of the model gun. Glock, Toz, Browing.
Your head is going to respond much the same way to all three in each case.

Have a look at the ARPANSA non-ionising exposure level vs frequency chart.
You'll notice something about it which reflects how microwave ovens work.

S-Band is used for Microwave ovens because food absorbs most of the RF power. If the wavelength was longer, the RF energy would just pass through the food without being absorbed.
On the other side of the coin, if the frequency is too high, then the RF energy is reflected from the surface of the material and again less energy is absorbed by the food.

The exception when it comes to the arpansa chart is the are some resonance issues when it comes to high power and humans. Some parts of them are more resonant than others.
The height of the person ~1.7m quater wavelength = ~40MHz
A person's arm ~75cm = 100MHz ..opps FM braodcast band.
Those RF skin burns from finding yourself as a quarter wave stub in a high power near field. Ouch !

===

I'm thinking about offering a service to deal with mental problems like fear of EM fields and other radiation.
It'd be some great money doing house calls for nut cases and sweeping their house with an RF meter and a geiger counter. I may even get myself one of those ghost busters ectoplasmic detectors too !

Here's a test I prepared earlier


If anybody really still has any doubts about the various forms of radiation after that then I can a site inspection of "trash labs" where I will scare the living shit out of them. Their home will from that day forward be viewed as a sanctuary !

[ericdog]

A person's arm ~75cm = 100MHz ..opps FM braodcast band.
Those RF skin burns from finding yourself as a quarter wave stub in a high power near field. Ouch !

Oh, no, now I know why my arm hurts... Must be from those years of tuning/working on those 20Kw FM transmitters at the 7/10 site at Artarmon....

Those were the days... now the old NEC and RCA (4CX15000 tube) transmitters are replaced with Harris solid state ones..

Oh well, thats progress for you !

And yes, I understand the "trash labs", it would be scary.. I have an "ericdog" workshop full of nasty RF gear too that would be almost as scary.. 10GHz at at decent power makes your eyes go all blurry!

Im sure I have been half-cooked inside from all the RF absorbed over the years..

[porkop]

Im sure I have been half-cooked inside from all the RF absorbed over the years..

mhhhh...medium rare ericdog

[Onefella]

Oh, no, now I know why my arm hurts... Must be from those years of tuning/working on those 20Kw FM transmitters at the 7/10 site at Artarmon....

My work has a 350kW Thomson, 2 x 300kW Thomsons and 2 x 150kW Continental tube transmitters, but we're only transmitting in the 900-1700kHz range. We still tend to avoid the antenna field when we're tx'ing though.

The 350kW unit alone uses ½MW when it's on full power. Glad I'm not paying the electricity bill.

[ericdog]

My work has a 350kW Thomson, 2 x 300kW Thomsons and 2 x 150kW Continental tube transmitters, but we're only transmitting in the 900-1700kHz range. We still tend to avoid the antenna field when we're tx'ing though.

The 350kW unit alone uses ½MW when it's on full power. Glad I'm not paying the electricity bill.

Sorry if we are a little O/T here, but, this discussion is interesting... We went from micro-power RFID to 5W on 2450MHz to 20kW on 105MHz to 350kW at 1000KHz...

350kW on AM, ouch, that is high power... It makes the little field from an RFID tag/reader pretty insignificant! Although, at 900 to 1700KHz, the 1/4 wavelength is long, 83m to 45m in free air!

350kW out/500kW in = 70% efficiency, not bad..

I wonder what tariff/rates per kWh (MWh) the broadcasters get these days?

[trash]

10GHz, my back shed is emitting a little higher in frequency.

[ericdog]

10GHz, my back shed is emitting a little higher in frequency.

He he he, I knew you would be emitting higher than that trash, you're a legend!

I can only go to 24GHz at 200W EIRP (directional of course), then I stop!

[Onefella]

350kW out/500kW in = 70% efficiency, not bad..

I wonder what tariff/rates per kWh (MWh) the broadcasters get these days?

Sorry to wander off-topic, but seeing as we're talking about RF fields..

The 350kW Txer is usually only putting out 300kW useful power when it's using 500kW total. We don't normally run at full steam except by accident or for testing.

At those sorts of power levels all sorts of stray RF fields develop. Doorways, certain steel conduits, even the chain on one of our roller-doors, can go RF "hot".

[ericdog]

Yeah, I can just imagine, Onefella what it would be like with pieces of metal becoming "receiving" antennas and RF hot spots on an AM TX site... Ive seen some strange things on these high power multi-TX sites....

Its all good fun and interesting to work on that kind of gear - I loved it when I was actively doing it in Sydney..