On 9/28/2015 6:18 PM, Ian Jackson wrote:
In message , Roger Hayter
writes



It would probably make more sense to call return loss "return gain",
but, since it is always less than one, that would merely cause a
different set of ambiguities.

The reflected signal is an attenuated version of the forward (source)
signal. It is a 'loss' - in exactly the same way as the signal at the
output end of an attenuator is an attenuated version of the source
signal at the input end. The RLR (in dB) is the ratio of the what you
put in to what you get out. It cannot be less than 1, so the RLR is in
positive dB. There is absolutely no ambiguity. No one in RF engineering
quotes or uses negative values for RLR (or for attenuators). The greater
the RLR, the less signal is reflected.

I have seen a number of references that give the formula as Pout - Pin.
Clearly both forms are in use. I can offer a book that shows a graph
of negative RL values.

https://books.google.com/books?id=nH...0ratio&f=false

--

Rick