There is a particular piece of digital signal processing used in radar (or at
least, it was in use when I was an undergraduate electrical engineering student
25 years ago) called the "chirp Z-transform." The singularities in the function
are called the "poles," after an analogue computing technique used in the 1930s
for finding those points. It may be that pilots are taught to figure out the
poles in the particular function in use and to fly a pattern that corresponded
to the singularity, or perhaps their onboard computers do this.

Just a guess. Perhaps there are some more current EEs reading who can fill in?

David

Paul Tomblin wrote:

I'm told that fighter planes use the same technique to evade enemy radar
guided missiles, flying an arc around the in-coming missile (although they
use terminology like "putting your z-pole on the target" or something). I
believe fancier radars can apply the speed gate to your speed even if it's
parallel to the antenna, even if it's primary only, but I don't believe
either ATC radar (which is, after all, designed to track cooperative
targets) or older missiles like Sparrow have that capability. I wouldn't
be surprised if AMRAAM and other newer missiles do.