Roger I was very fortunate in that my second job out of college (I got a BS in electrical engineering) was with HP. Back when HP was the instrumentation company. In those days (1982) I doubt anyone would disagree that HP was THE premier designer of RF test equipment. VERY active in everything RF.
As part of the training for sales people, so we could intelligently talk with our customers, they spent 9 weeks, in 3, 3 week segments, teaching us the basics of rf and of their instruments.
While much of what I learned has been relegated to the dust bin in my brain, a few things remain. One was that return loss was always positive. If you do the math this will be born out. If you just think about it, its a ratio of incident vs reflected rf (or maybe the other way around. I just don't recall). A ratio of two rf power levels should always be positive. But again, do the math.
Sure many many folks make it negative. Many, in their explanation, first say one thing then later in their article, the other. Of course confusing! And some conflate return loss with insertion loss. But, insertion loss will also always be positive so I've not understood that one.
Anyway, as you said, its an argument that's been around forever. And, one side will always be wrong :)
Ron
N4XD
