Hi! I've build a RFID reader with my Arduino to read HF Tags. HF is considered to be 13,56 Mhz. I've ordered HF NEOSID Tags: https://neosid.de/produkte/rfid-tags/hf-tags/52340/neotag-plug-mfg-4335-slix?c=188 . But now I realized they have a frequency of 13,1 Mhz so I cant read them with my Arduino. I thought HF is always 13,56 Mhz. Has someone an explanation why this is the case or a solution how to change my arduinos frequency?
Thank you! 
BuildBoy:
Hi! I've build a RFID reader with my Arduino to read HF Tags. HF is considered to be 13,56 Mhz. I've ordered HF NEOSID Tags: https://neosid.de/produkte/rfid-tags/hf-tags/52340/neotag-plug-mfg-4335-slix?c=188 . But now I realized they have a frequency of 13,1 Mhz so I cant read them with my Arduino. I thought HF is always 13,56 Mhz. Has someone an explanation why this is the case or a solution how to change my arduinos frequency?Thank you!
The ISM bands used by various RFID tags are a small range of frequencies, so a manufacturer can use any part of that band they want.
Paul
If you download the datasheet it specifies 13.56 Mhz. The band actually covers 13.1 - 13.7 Mhz. Perhaps it's a typo or the upper band got cut off... who knows. It should work.