i don’t think that this is really a problem of x-band because a object can also be optimised to have a small rcs in s-band instead of x-band. for sure making radar absorbing materials for longer wavelengths is a problem but imho it is to much simplified that a s-band radar will detect a vlo e.g. at horizon search before a x-band can detect it.

Making RAS/RAM for S-band and longer bands is a bit of a _big_ problem—LITERALLY—on a small airframe. Its a much better choice to VLO on the X-band because of the size considerations, making it harder to lock and guide a missile against it instead.

there are dozens of parameters which have to be considered. e.g. do we speak about a low flighing target which pops up at 30 or 40 km or about a target flighing high enough to be detectable at 150 km? the first one should be no problem because a primary design goal for apar was the early detection of sea skimmers; it performs well on low flighing objects and at this range there is enough power to make vlo targets visible. the maximal horizon search range of apar is quoted to be 75 km which makes sense to me. a high resolution mfr is neither designed for long range search nor is it very useful here. a dedicated long range volume search radar can be used to start a cued search and tracking of targets with the mfr.

APAR’s relative short range to SAMPSON lies not just in using a higher wave length, but that its also in CW as opposed to PRF. But then again CW is likely to expose a target with more energy than PRF over time, and that what’s make VLO objects visible.

i think this is also the main reason why the type 45 also carries the s1850m. bae and others don’t get tired to claim that sampson doesn’t need a second vsr but there is no info about power/time budget if sampson is used without a second vsr.
if i got an initial track from the vsr and if the mfr is not used for volume search, it has much more time for tracking these targets. if the target is difficult to track, more time/power etc. can be used on it.

I think the SMART-L operates at 1-2GHz, while SAMPSON is at 2 to 4GHz. So the two is close. I think that’s what BAE meant.

and using a s-band mfr doesn’t change much on the vlo example if the sarh needs x-band terminal illumination or if the arh-sam has a tiny j (ku)-band seeker. vlo-targets will reduce the performance of all of these systems.

(btw the rcs of a bird at x-band is about 10^-3 to 10^-4 sqm)

Still, having to engage earlier is better than engaging later, as we are all dealing with probabilities here, and we want the probabilities to stack up in favor as high as possible. To lock on and engage the VLO target optimized at X-band is a separate issue that can be handled by a separate development. I suspect if you start getting creative with the way the illumination X-band is modulated, just a theory of mine, it may be possible to lock on to the object. This is something potentially in favor of APAR due to its high power, frequency agility and backend electronics compared to a tiny ARH missile seeker.