Abstract: The proximity readers for opening a door are typically located on a lock, a metal prison wall, on a metal fire door, on a metal door frame. Traditionally, a proximity reader had to be made thick so that the pickup coil/antenna was not close to the metallic mounting surface otherwise the reader's read range would be drastically reduced. The present invention eliminates the problem of these metal surfaces reducing the read range of the proximity reader when mounted on these types of metallic surfaces. The present invention allows the pickup coil/antenna to be mounted close to the metallic mounting surface, be low profile without reducing the read range.

Abstract: An intrusion detection system employs a microwave subsystem and a passive infra-red subsystem. Both systems must produce an output signal indicative of an intrusion in order for the system to produce an alarm. There is disclosed a supervision circuit which monitors the number of trips of the microwave system as well as the number of trips of the PIR system. If the number of trips which are indicative of false alarms exceeds preset counts then an alarm is produced indicating that there is a failure in the microwave or the PIR system. The system further monitors the microwave system to determine whether the transmit and receiving diodes are functioning properly. The system will also indicate a fault if an intruder or an object is placed within a predetermined protection dome implemented by the system. Hence the system can produce multiple faults indicative of subsystem failures to notify the user of the system that such a failure has occurred.