A system and method for monitoring the inventory of a medical storage container that has a required inventory of medical articles. An enclosure is used to isolate, scan, and take an inventory of a tray or other container of medical articles each of which has an RFID tag. The enclosure having a size smaller than the size needed for a resonant frequency at the RFID frequency of operation of the tags. An injection device is used to create a robust electromagnetic field standing wave of constructive interference in the enclosure and a program compares the scanned present inventory of the tray to the required inventory database and indicates any differences. Expired and recalled articles are identified.