Comparison between millimetre waves and infra-red for short-range surveillance

The system characteristics of short-range surveillance by millimeter waves and by infrared are described and contrasted. The basic advantages of IR are its passivity, day and night detection ranges of at least 5-10 km on aircraft targets, the elimination of mutual interference problems, and typical angular accuracy of 1 mR resolution in two planes. Some of the disadvantages are that no range or velocity is intrinsically available, that the performance depends on weather conditions, and that a considerable burden is placed on the data processing system in trying to reject all signals except the target. In some ways, the pros and cons of mm radar are the antithesis of those for IR. A hybrid system combining both systems is deemed a very attractive possibility.