Question: It is known that S400 SAM is capable to detect any threat from 400km apart & shoot down, my question is Earth is round so normally stationary/fix located radar have limited capabilitie to detect long range threat due to curvature of the earth. How S400 SAM is capable to detect long range threat? ~ Prajapati Maulik
The entire effectiveness of Air Defence is based on layered sensors and weapons. And working together only the system itself is safe and provides the airspace denial to adversary. S400 is a component of this layered defence.
It is correct that the curvature of earth along with features like mountains and valleys reduce the effectiveness of a radars capability. But then again S400 relies on several components, not just one. Here as the question is focused on the long range 40N6E missile which can take down targets at 400km range, I will focus on sensors useful for this only and not the ones for smaller ranges.
The basic S400 detachment/deployment is based on a S- Band Panoramic Radar 91N6E (Big Bird) which can pick up an AWACS/Bomber sized targets at approx 550+ kilometres in ideal conditions and a fighter jet sized target at upto approx 350 kilometres. It is necessary to understand that the ultra long range 40N6E missile with 400km range is used against larger aircrafts like bombers, AWACS and Tankers usually.
The 91N6E is supplemented by a 400km range capable multifunction radar 92N6E (Gravestone). It is the fire control and tracking radar for S400. These two radars can track and manage between 100-300 targets at a given time. These two radars are sometimes supplemented with a 96L6 Cheese Board 3D surveillance and tracking radar to augment it’s capabilities.
For long range anti stealth operation against stealth bombers , a special radar functioning in UHF mode is added. This may not be cleared for export.
AWACS can provide target and mid course guidance updates to the long range missiles too. But it will need data links for this capability.
Hopefully this solves the question of how is targetting at such long ranges possible?