I recently purchased the SonMicro SM130 chip for a few RFID projects that I’m working on. It worked great – Tom Igoe’s Processing library (http://www.nearfield.org/2009/04/sonmic … ng-library) made it really easy to communicate with the chip, and the firmware updates let me read multiple tags simultaneously. However, I need a bigger antenna for a variety of reasons – SonMicro’s antennae are simply too small for my needs.
Given that this is a 13.56 MHz RFID system, I assumed that any 13.56 MHz antenna would work. So I bought a Feig Antenna (http://www.digikey.com/product-detail/e … ND/1015926) that was the size I needed, hooked it up, and… it, well, sort of worked.
Tags can be read if they’re right around the coils, but there’s a huge ‘hole’ in the center of the antenna where tags cannot be read. I’m assuming this means that either the antenna can’t get enough power from the reader, or that the antenna isn’t properly tuned for the chip. Is there a way I can test which one is the case? If it’s a power issue, I may be able to amplify the signal (depending on exactly how the RFID is read), or I could find a way to tune the antenna if it wasn’t quite right.
Regardless, I need an antenna approximately 12" x 12" – I can either find a way to make this antenna work, make my own antenna, or move to a new chip that already has a suitable antenna built for it. Does anyone have suggestions / recommendations for how to do this?
thanks!