Abstract: An intelligent security system capable of sensing the presence of an object to be identified, interrogating the object with an encrypted code, and receiving and processing an encoded response from a passive transceiver carried by the object so that the intelligent security system can be utilized for controlling access to a location, performing inventory control, controlling toll access systems, operating multi-station complex machinery systems, or providing object locating information, for example. The intelligent security system is particularly characterized by its utilization of a totally passive transceiver including a transmit circuit which will only be activated upon receipt by the transceiver of a predetermined encrypted interrogation signal. In response to receipt of a proper interrogation signal, an encoded response signal is transmitted by the passive transceiver and then received, decoded and processed by other elements of the security system.

Abstract: An improved electronic article surveillance device of the type utilized a parallel resonant circuit and primarily intended for use in tagging retail items for the purpose of preventing unauthorized removal of theft of such items includes, within the parallel resonant circuit, at least one transmission line resonator whereby the device may be easily and efficiently deactivated. The length of the transmission line resonator is one-quarter wave length of the deactivation frequency, and deactivation frequency is preferably selected from readily available electromagnetic radiation such as, for example, microwave energy or police radar energy.