EAS system with alternating on/off transmitter operation and loop antenna

摘要

In an EAS system a transmitter alternately drives first and second antennas with the same coded message signal in its entirety. The antennas, in turn, transmit first and second signals each containing the coded message signal into respective first and second partially overlapping parts of an interrogation zone. Also disclosed is an antenna structure comprised of a plurality of loops extending one after the other and successive ones of which are of opposite phase. One of the loops circumscribes an area which is smaller than each of the other loops to realize reduced coupling to adjacent structures.