I am working on a project that requires a larger-than-usual RFID anteanna read surface. I don't need long range, but I need it to read the tag over a 6" diameter circle. To accomplish this, I decided to make my own custom antenna (as done in these tutorials: One. Two)
However, I have a different RFID module than the one used in the videos, and I'm unsure of if it uses the same inductance in the antenna, which is necessary for designing my own.
In googling around, I have found a few data sheets for my module (such as here) but they only seem to have pinouts and state that it works with an external antenna, with no info on the antenna itself. I don't have an oscilloscope or anything else that would be able to determine the inductance of the provided antenna (unless someone knows how to do this with a basic multimeter). I've even tried to google the three main components on the board in the hopes that one of them is the actual RFID chip (equivalent to the ID-3LA in the videos) and would have that info, but they seem to be a signal booster, a microprocessor, and a voltage regulator, with no info on antenna requirements.
If anyone knows either where I could find the info, or if I can assume that all 125Khz RFID modules will have the same inductance (so I can just use the value from the ID-3LA chip), that would be greatly appreciated. Thanks.