Reg Edwards wrote:
Forward and especially reflected power are even more imaginary than
the SWR on a non-existent 50-ohm line.

My old Heathkit HM-15 SWR meter samples the peak forward and
reflected currents. A pot is used to set the meter to full
scale using a voltage proportional to the peak forward current.

When the voltage proportional to the peak reflected current is
then switched into the meter circuit, it reads SWR from the
precalibrated scale which is linear with |rho|, i.e. at half-scale,
SWR=3 and |rho|=(3-1)/(3+1)=0.5
--
73, Cecil http://www.qsl.net/w5dxp