Cecil Moore wrote:


Quoting "Optics", by Hecht, Chapter 12. "Thus far in our
discussion of phenomena involving the superposition of waves,
we've restricted the treatment to that of either completely
coherent or completely incoherent disturbances. ... There is
a middle ground between these antithetic poles, which is of
considerable contemporary concern - the domain of
*partial coherence*.

"Contemporary" is an interesting word choice. Partial coherence has been
recognized for a long time. There is a very widely referenced paper by
H. H. Hopkins on partial coherence in optical imaging systems that was
published in 1950. He did not invent the concept, but he did popularize
the standard formulation still used today. The math is a bit messy, with
4 dimensional integrals and other complications, but numerical solutions
are widely done.

I would be quite surprised if the radar and other RF experts don't use
the same type of analysis.

Oh, by the way, even a completely monochromatic wave can be partially
coherent if the source is extended. Indeed, that is one of the more
common configurations.

73,
Gene
W4SZ