what is the cut off frequency of a filter?

Hi,everyone,I want to design a filter for RFID reader. But I want to know what the cutoff frequency usually should be. And some paper say the bandwidth of the filter could be tuned. Does the the filter of the reader have no fixed cutoff frequency?Why?Thanks to everyone!

Which RFID standard you're referring to?

Generally, the transmitter part of a reader has most likely a low-pass filter to supress harmonics, necessary to comply with RF regulations. Some readers (particularly 13.56 MHz) also involve tuned antenna filters.