I'm starting a project to create an RFID writband. I'm planning on putting tags on common objects so that I can use the wristband to detect when I'm holding something. I've googled a bunch but haven't found this implementation using Arduino.
So far I've chosen the 13.56 MHZ frequency because it's low power, has good penetration through metal and water (i.e. flesh). I've bought the SM130 module from Sparkfun and I have an Arduino Uno for prototyping (eventually I will switch to a smaller arduino). I'm hoping to get a range of about 10-15 cm from the bracelet.
My question is all about the building of the antenna. Should I use a PCB antenna or make a wire loop antenna that would fit around the wrist? What's the optimal length and the optimal amount of loops for my purpose? Basically any information about how to select an antenna design and how to build it would be very helpful...
My opinion is that if you have to ask, you are not ready to design an antenna, and you should rely on an expert to design (and manufacture) an antenna optimized for the RFID reader you are using.
10 to 15 centimeters is NOT a trivial distance. Most RFID readers are in the 1 centimeter range.
Not the most helpful of comments previously but does make some valid points. By the sounds of it you might be embarking on a highly iterative process. My advice would be to buy some RFID wristbands, test them with your readers, break them open and observe what others have done and how they ahve designed their wristband for each level of performance. You'll soon get a feel for it and it is the best way to learn rather than be told what to do. You'll understand the fundamentals that way/
If you are using 13.56Mhz I would go for PCB antenna (FR4) and work from there, but go with above route first.
Word of caution - 10 cm is a litte ambitious for HF.
Also keep an eye on the actual application i.e. what your end game is. You product will need to be robust enough and operate within its intended environement.
Good luck - sounds like fun.