RFID and antishoplifting systems are different. AS use (most of case) passive tags: RF-systems use precisely tuned tank cct. for 1.75,1.95,2.125 MHz with start-stop TX, 3.5,8.2 and 10MHz for sweep TX.
Magnetic AS-systems use two low freq. for detecting a special alloy (unfortunately some japanese umbrellas also contain it... :lol: )
Magnetic-ultrasonic AS-sytem use magnetic TX and ultrasonic RX for detecting a mechanical resonator in the tag.
RFID use - most of case - a 125kHz TX and these energy activate the processor in the tag, who start transmit a unique code.