Linear virtual fence system using radar and reflector

A system comprising:

• a radar including a transmitter and a receiver, the transmitter configured to transmit an electromagnetic wave;
• a reflector placed a predetermined distance away from the radar, the reflector configured to reflect the transmitted electromagnetic wave back to the receiver;
• and
• a control unit coupled to the radar and configured to
• measure a magnitude of the reflected electromagnetic wave received at the receiver from the reflector by measuring received Doppler signals,
• wherein the control unit is configured to measure a reference value of the magnitude of the reflected electromagnetic wave when no intrusions are occurring if a received Doppler signal is within a percentage tolerance that indicates that the received Doppler signal corresponds to the predetermined distance of the reflector, and
• in response to the Doppler signal being within the percentage tolerance the control unit is configured to monitor for intrusion and trigger an alarm indicating intrusion when the magnitude of the reflected electromagnetic wave changes from the reference value.