An attack warning system for alerting ground troops or ships to the possiity of attack by enemy aircraft. The system establishes a detection shell at a range of 3 miles covering 360.degree. in azimuth and 60.degree. in elevation. The bearing measurement is obtained by a combination of antenna pattern...http://www.google.de/patents/US3956749?utm_source=gb-gplus-sharePatent US3956749 - Bearing measurement device for a portable attack warning radar
