While testing out the new PN532 NFC/RFID Breakout Board, we tried comparing the range of our board with some of the commercial NFC devices we have in the office that are also based on the PN53x family. It's not really fair to publish any numeric comparison since, particularly with RF, there are always a number of compromises and choices to be made between physical size of the device/antenna, power consumption, etc., all of which change with the intended use of the device. Suffice it to say that we're extremely happy with the performance of our own open-source board thanks to the great work of Roel Verdult and colleagues from the libnfc project, but obviously a small USB-stick device like the SCL3711 (SCM Microsystems) is going to have different perfomance characteristics than a much larger antenna like that found on our own board or the commercial ACR122 reader (Advanced Card Systems). They don't have the same intended use and so comparing metrics like absolute range isn't particularly fair.
The SCL3711 in particular, though, is an interesting device since it packs what should be a fairly 'large' antenna into a very small package. We were kind of curious how they accomplished this, but weren't all that keen on pulling apart the only device we had lying around since we were still using it for testing purposes. Thankfully, most commercial devices have a little number on them that often provides a window into what's inside your device without having to pull it apart yourself: the FCC ID.
As was recently mentionned over at Adafruit (Symbols and FCC IDs), itself a repost of a response over at ars technica (Ask Ars: What are those symbols on the back of the iPhone?), you can often use the FCC ID to find photos of the PCB or inside of the device, along with test-results and a number of potentially useful technical details. As an added bonus, if you're interested in the different tests that devices need to go through to pass certification for agencies like the FCC, spending a few minutes reading through the documentation for a few products can be very illuminating.
If you look at the back of the SCL3711 (a small USB-stick sized 13.56MHz NFC/RFID reader based on the PN533), you'll see the FCC ID MBPSCL3711-0200.
The first three letters ("MBP" in this case) represents the "Grantee Code", and the remaining letters and numbers are the "Product Code" (SCL3711-0200). By entering these two values in the FCC's FCC ID Search Form (http://www.fcc.gov/oet/ea/fccid/) you can probably find some useful information about the product in question.
The initial search results for the SCL3711's Grantee Code and Product Code can be seen below, showing two different entries:
Click on the first entry, we then get a list of publicly accessible documents associated with this product/FCC ID:
While we can't publish the photos for copyright reasons, you can see photos of the front and back of the PCB in "Intenral Photos" (sic.) where the antenna and 27.12MHz crystal are clearly visible on the back, and the PN533, inductors, antenna matching network, etc. on the top. "Test Setup Photos" contains a number of interesting photos if you're curious about the testing process as well. While most companies request confidentiality for the schematics, etc., you can still learn a lot about different devices through the FCC database without having to pull your devices apart. Though, of course, pulling things apart can be enlightening as well, particularly if you're interested in how the physical assembly of common devices is made!
In this particular case, the PCB is quite well layed out, which isn't surprising since the device has decent performance for something so small. Particularly for RF devices, using the FCC ID can often provide a starting point to your own antenna design. If you're just getting started and wondering how other people have solved problems like fitting large antennas into small packages, this can sometimes be a great place to start.