Cecil Moore wrote:
The SWR bridge samples the current and voltage and
performs a phasor addition and subtraction to get
voltages proportional to the forward and reflected
powers. If there is a high voltage caused by reactive
components, it will be close to 90 degrees away from
the current. But phasor adding these two values gives
something slightly greater in magnitude than the high
reactive voltage. That high voltage gets rectified and
displayed as the forward power when it is not actually
the forward power but reactive power flowing from one
reactance to another.
--
73, Cecil, W5DXP

The power flow fairy sure has a lot of warts. :-)

73, jk ac6xg