Digital devices that have a power consumption not exceeding 6 nW are exempt 
from specific technical standards per FCC Rules 15.103(f).

There are no such exemptions for intentional radiators. See FCC Rules 15.225 
for radiated emission limits applicable to radio devices operating on 13.56 MHz.


Best Regards,
Mike

From: Ken Javor <[email protected]>
Sent: Friday, October 19, 2018 5:54 PM
To: [email protected]
Subject: Re: [PSES] NFC (near field communication): FCC Approach?

I don't know what the FCC rules are on something like this - others on this 
forum are much better informed on that topic - but if the ERP is 0 dBm (1 mW), 
then at three meters away the field intensity would be 58 mV/m, or 95 dBuV/m.  
Now this is at 13.56 MHz, where there is no FCC RE limit. But the FCC Class B 
three meter limit at 30 MHz is something like 40 dBuV/m (someone jump in if I 
got this wrong) so that means the third harmonic must be 55 dB down from the 
fundamental.  That is certainly doable, but I wouldn't take it for granted 
without some sort of verification.

Ken Javor
Phone: (256) 650-5261


________________________________
From: MIKE SHERMAN <[email protected]<mailto:[email protected]>>
Reply-To: MIKE SHERMAN <[email protected]<mailto:[email protected]>>
Date: Fri, 19 Oct 2018 17:22:50 -0500
To: <[email protected]<mailto:[email protected]>>
Subject: [PSES] NFC (near field communication): FCC Approach?

Esteemed fellow listers --



I'm looking at a very low power, intermittent NFC card reader/writer. Alkaline 
battery operated device. NFC is only energized for 10 seconds at a time on 
demand, and range to read/write is less than 1 cm from the surface of the 
device.



I'm not an EE, but my simplified thought process is: "I can barely get this to 
couple magnetically with a card sitting on its surface. How could I possibly 
interfere with broadcast services or other equipment?"



So, oh wise ones, from your experience what actions with respect to FCC are 
reasonable to do? For example, radiated emissions testing seems to me like a 
total waste of time and money.



More technical details: maximum input power to the NFC chip is 17 mW. Chip is 
coupled to a flat 30mm x 40mm "NFC Ferrite Antenna (13.56 MHz)" that my EE 
describes as "zero gain." We're rating RF output as 0 mW (i.e., rounding off, 
it's a lot closer to 0 mW than to 1 mW).



Looking forward once again to interesting wisdom from this group.



Mike Sherman

Graco Inc.
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