Dear all, This is my first post in the forum. I am working on a RFID technology used in door opening systems. The wall readers, we use are typically placed behind the door, as is the case with the metal being used on the front side of the door and in the key hole casings there is the obvious problem of intereference by the metal in communication between the RFID tag & reader. So we thought of experimenting, by bringing the antenna of wall reader a little forward i.e. to be placed inside of the KEY HOLE CASING (made of metal) on front of the door while keeping the main electronics of the wall reader behind in hopes that bringing the antenna forward would help in the communication between tag and reader, BUT it doesnt work as the reader antenna coil is placed directly on the KEY HOLE CASING courtesy Eddy currents et al. Acc to the RFID H-book, by introducing a highly permeable ferrite btw the antenna coil and metal surface it´s posssible to prevent the occurence of eddy current (Sec 220.127.116.11) I would like to know about the highly permeable ferrite. exactly what kind of ferrite should I use [dimension (MAX. PERMITTED THICKNESS: 3-4mm, 52mm x 35mm), material etc]? If anyone has worked on this problem, can you share some details? Retuning the system, isnt allowed. Please suggest about the ferrite material, ways to enhance the T<--> R communication and any other ideas you have. I hope, I was able to communicate my problem clearly. Thanks in advance, Kern P.