I should explain the situation regarding the Rafale radar.And I had also believed that Rafale's superiority is ensured only with the arrival of GaN for radar and EW suite by 2025. Sadly, even that's been postponed to 2030+. Now we know that the radar will be the same one as before, which puts it in the same class as what DRDO has already developed for the LCA, and they also claim it's better than what's on the Rafale. And F4.2 largely serves as a program meant to bridge the gap between the Rafale and F-35, like the addition of AGCAS and patrol link. GaN by 2025 was necessary to compete with the J-20, but now both F-35 and Rafale will get GaN around the same time.
First I would like to talk about pulse compression, which is a process used to emit more energy to the target by spreading it out in time and compressing the return signal to get a detection.
I've already talked about it using the example of compression up to 30, because I thought that larger compressions were classified, and then I read in open source that the order of magnitude of the compression used by the ATL2 radar was of the order of 500. So that allows me to take more realistic examples for the Rafale.
Then I was also disappointed not to hear any more about GaN for F4.2, but a Thales insider told me that the price of this technology had dropped but that it was still expensive, so in the meantime we are doing something else: what is being developed is a multi-channel receiver, I was told that it also increases the range and that it has other qualities.
It is considered a new generation, the AN/APG-85 that will equip the F-35 will be multi-channel and so will the ECRS Mk2. Using this technology before GaN is interesting because the longer you wait for GaN the cheaper it will be, while the price of multi-channel is the same now and later.
The Rafale AESA antenna allows a detection of 160 km for a 1 m2 target, so assuming that the F-35 has a RCS of 0.0015 M2 it will be detected at 31.5 km. If we switch to GaN we multiply the power by 3 and the range becomes 41.5 km.
All this is well below the IRST range, which can be estimated at 100 km to detect the F-35. But we still have to measure the distance and for that we can use the Radar that we point in the direction given by the IRST, with a pulse compression of 100. If we have a GaN antenna, the necessary compression will only be 34. This is an advantage, but it is not essential.
On the other hand, one could not use these levels of compression to scan a large area, or one would have to do it very slowly so as not to generate heat that could not be extracted. But for one track or even 40 the extra heat generated is negligible.