Chipless RF identification (RFID) technology has emerged as an alternative to RFID systems that have tags equipped with silicon integrated circuits (ICs), or chips [1]-[12]. The main advantage of chipless RFID systems over their chipped counterparts is the lower cost of the tags, which results from the fact that the ID code is contained in a printed planar encoder (implementable with conductive inks) rather than stored in a silicon chip. Low-cost tags (below the USd0.01 barrier) are necessary in many RFID applications involving items that have a moderate or low price and where chip-based tagging would represent a significant penalty in terms of the overall expense.