Both are 90 degree elbows- from my measurements the ones that have a
square block of metal at the elbow were fine. The ones that looked like a
90 degree plumbing sweep had bad return loss. This may vary from mfg to
mfg, but Al Ward W5LUA who has had experience up through 24GHz agrees.
Perhaps I'll get time and inclination to mill one of the sweep styles open
and see what's up.
Dale W4OP


This is a very strange result, the non 90 degree elbow ones, normally
referred to as "swept radius" are intended to reduce the step
discontinuities that the a 90 elbow type introduce. They are usually used at
microwave frequencies where these discontinuities are more apparent.

73
Jeff