Electromagnetic Applications in
Security and Surveillance Systems
Security and surveillance systems are used throughout business establishments and households. Most types of systems have electromagnetic applications. The two systems I'm going to focus on are electric circuit security systems and electronic article surveillance systems. One is used for monitoring commercial goods and the others for intruder safety purposes.
Electric Circuit Security Systems
ECS are used for security rather then surveillance. These types of systems can be simple electric circuits. When the circuit is closed that means the window or door that it is on is also closed. When the window or door is open it opens the circuit, therefore sounding the alarm. Closing the door cuts off the flow of electricity through the circuit which then triggers an alarm.
EAS systems are used mainly for commercial purposes. In EAS systems there is always an antenna and different electromagnetically charged tags(as seen to the left). The antennas are constantly emitting electromagnetic energy. On the antennas there is a transmitter and a receiver. "The hard tags or labels themselves do not contain transmitters but an electric current is generated by the electromagnetic field of the antennas." The tags are either activated or deactivated. When they pass through the antenna and they are deactivated the alarm doesn't sound. "Electric current is only generated during the short moment that the article is carried past the detection antennas and an electromagnetic interaction occurs between the antenna and the hard tag."
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