Richard Harrison wrote:
A Bird senses all it has to sense and legitimately converts it to a
reasonable indication of watts. The Bird can do so thanks to Ohm`s law,
and that`s that.

Let's approach it a little differently. Assume a signal generator equipped
with a circulator load driving a lossless 50 ohm feedline. The load is
variable.

100W SGCL----50 ohm lossless coax--------variable load

Are there any locations up and down the line and/or any value of
load that will cause the Bird wattmeter not to read 100 watts
forward power? In the above example, I can show that the two
voltages that get added inside the Bird always yield a constant
value of voltage, i.e. and therefore a constant power indication.
--
73, Cecil, W5DXP