DANIEL M. DOBKIN, Enigmatics, Sunnyvale, CA., STEVEN M. WEIGAND, WJ Communications Inc., San Jose, CA

Basic antenna theory shows that the scattering cross-section of an antenna is often much larger than the physical cross-section of the metal wires from which the antenna is constructed. In the case of RFID tags, a large number of tag antennas may be present in close proximity to one...