The following topics are important, but didn't seem to  fit neatly anywhere else.

The 3 presentations below are for:

180 degree duHamel coupler

90 degree LC phase network (a 1967 simulation benchmark)

90 degree Gingell Polyphase RC  network

and here is a javascript routine for designing Polyphase networks with optimum RC values for an equal ripple error:

 Polyphase RC Network Calculator ,

Just a two-slide sim result below duplicating the results of Carl Pfeiffer at Microwaves101 for an asymmetric tapered line 180 degree duHamel coupler.    Carl's simulation is here .