W5DXP wrote:

Nope, they're not Reg. For Z0-matched systems (which most ham systems are),
rho^2 is all you need to know along with the forward and reflected powers
to completely solve the voltage, current, and phase conditions at the
impedance discontinuity.

There in one sentence is the whole problem with the "power" approach.
For a complete solution including phase conditions, you have to assume a
Z0-match, and even Cecil acknowledges that is only true for "most ham
systems".

As Reg says, this is because the power approach throws away the phase
information at the start, and if you want it back again, you have to
make assumptions.

So the problem is not that the "power" approach cannot give a complete
solution, but that it cannot do it for all cases. In other words, it
isn't completely general - and that flaw is fatal.

The conventional approach based on voltage (or current) waves doesn't
discard the phase information, but uses it to give a complete solution
for every case. It is completely general, and that's precisely why
engineers use it.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek