I am working on a smart shopping system and would like to know if a UHF rfid signal can pass through few layers of clothes in a bag as multiple clothes would be present in a bag and system has to detect it correctly.
I have experience only with some very simple RFID systems about 10 years ago, so I don't know what advances have been made recently, but from what experience I have, I can say that it'll pass through the fabric, but it's probably an ineffective mechanism against theft as the customers can shield their bags.
Furthermore, I think most RFID tags need very close distance between the reader and the tag (a few centimeters) so you'd need to choose a tag that can be read from further away. And then it might be difficult to be sure exactly who has the item in his/her bag when they walk out the store. Also, you must make sure that if you have several RFID tags in the bag, you can still read them separately without them interfering with each other.