Richard Clark wrote in
:

....
We've been through this before. No instrument operates in the absence
of power. Simply because you and Owen are graced with instruments
that demand so little, does not negate what power they do rob from
what is available. Even the humble electrometer has to overcome the
force of gravity to open its foil leaves, and climbing that potential
energy hill is work over time - power.

Hammer down the directivity as much as you want, and it will still
resolve to some diminution of power available to the load. To wave a
hand and say NOTHING does not make it so.

The fact that an instrument may consume power from the circuit does not
imply that it measures power.

For example, a "voltmeter" that samples the voltage and draws a small
current from the cicuit under test does consume some power, but it cannot
"measure" power in the circuit under test without knowledge of the
complex load impedance.

I wrote an analysis of the Breune circuit and show that the meter
deflection is a response to the Vf or Vr component, and I dealt with how
that information can be used (including applicable conditions). If you
(or others) think there are flaws in the article, I welcome constructive
feedback.

Owen