the APG66 is a doppler radar. Learjets have that for weather radar now. And AIM 9 won’t need radar regardless since it is IR.
There is really no such thing as shoot down for that slow a speed. AMRAAMs have semi active terminal guidance so there’s no huge need. And the whole point of the matter is not to have to look down. These are slow vehicles and they are not terrain following. No reason to be above them.
But it’s all meaningless. You should not be wasting manned aircraft on cruise missiles if you have any reasonable integrated air defense.
It’s probably all bogus anyway.
AIM 9 doesnt have the range for this - engagement volume is a big issue - you want to track and engage multiple targets over a large area, not have to close in to engage targets one by one. Also look down with IR missiles is a problem.
Plenty of reason to be above them. Way above them, in order to track and lock multiple targets coming from many axes.
F16s are near ideal.
Ukraine has an integrated air defense system, its just short of missile batteries, as its friends have never provided enough to replace its out of ammo S300 systems.
The other big advantage of F16’s is that they can take off and climb really fast. A bunch of F16s on cockpit alert can be at 30,000 feet in 2-3 minutes or less. Ukraine gets much more alert time than that - Ukraines friends will certainly tell them when a buch of these TU95 or TU22’s have taken off. These TU95 and TU22’s are the primary cruise missile platforms and vital to any saturation attack. So they can be up high enough very quickly to do the look down-shoot down.
And then there is speed - they can do Mach 2, which is important for an interceptor. They can be dispatched in time, from CAP or takeoff, to probable missile tracks.
All of these things are major advantages when the Russians send a saturation attack.
The main similarity it has with possible Learjet radars is the planar array, which likely don't have coherent pulse doppler or monopulse (3-channel) processing which are going to add more hardware and processing on the down side.