Increased importance of VHF radars in ground-based air defense

The basic military operational requirement for air defense surveillance systems is to detect all kinds of threats in the airspace, to identify or recognize them, and to track them. The population of civilian aircraft with low radar cross section has increased, and their density in air surveillance areas has also increased. Interference resistance of long-range radars, which are essential for the defense of national airspace nowadays, is weak compared to improvements in electronic warfare, extensive use of passive and active capabilities. A compromise has to be found between the reduced probability of detection and the required signal-noise ratio for a good quality of target detection. The track and plot fusion solutions have been described above. The fundamental idea of the coherent processing is to make more effective use of information contained in the spatial characteristics of the electromagnetic field.