Building a UHF RFID Reader, FCC regulations?

Question

I've been working on a project that involves tiny UHF transponders (ex. OMNI-ID Fit 220) that fit into a product with very limited space. We wanted to build our own reader (5 or 6 of them) because it's cheaper, easier to integrate into our system using a reader board and a little Arduino, and we can utilize the reader for our application better. We aren't exactly electrical engineers but more hobbyists as the place we work usually like to build everything in-house so that's why we went this route, we have access to everything possible to build one ourselves. We had very poor read results and reliability with the Sparkfun M6E Nano, so we abandoned that module. So I brought in some evaluation kits (Impinj RS1000 and STI) We were really happy with the Impinj development board but Impinj is telling us we need FCC approval and UL certifications to build our own device. Is this correct? To my knowledge I thought as long as we didn't exceed 1 Watt in TX power and move out of the UHF frequency range here in the FCC we would be fine to use our small batch of devices, we wouldn't even sell them.

The readers we have seen are around $1000+ or USB desktop readers but cheap. If we 3D print our own cases and build them ourselves our costs would be only ~$300-$400 per device.

Do the FCC regulations stop us from building our own reader device? Do we have to get approval that doesn't go over 27dBm? I can't exactly find anything saying so.

Am I missing something bigger?

Thank you!

Answer 1

I recommend going over TI's technote ISM-Band and Short Range Device Regulatory Compliance Overview.

Big takeaway: Unlicensed != Unregulated.

Unlicensed means that the users of your systems don't need a license and that would be the case if your device complies to FCC Part 15 (ISM or non ISM).

Regulation means that any device on the US market must go through the compliance testing in order to ensure it meets FCC Part 15 specification.

FCC requires to test all transmitters but not receivers. However, for receivers you still need to write a document (DOD) describing how your system is Part 15 compliant.

Now (fully passive) RFID is a special case because it uses passive backscatter. RFID itself is never mentioned in Part 15 but FCC has published for few memorandum on how they treat these systems. Essentially they do not treat the tags as active radiators which hence do not have to be tested. However, readers (being active readers and transmitters) have to be tested.

So, if you sell your product in any way in the US ("on the market"), it must be tested and certified. For internal setups and usage this may not be necessary.