Systems used in an external environment to detect the presence of an intruder attempting to breach a defined perimeter. An Example of a Perimeter Intrusion Detection System is our HALO system. Our systems deliver maximum protection of a perimeter due to advances in Microwave Technology and Signal Processing. This allows our systems to employ a detection zone of up to 200m in length, 12m in height and as narrow as 1m in width at optimal deployment.