Assuming the transmitter does not fold back, the 11% reflected power
will not change the signal strength... The reflected 11% will be 88%
radiated on the return trip (minus any line losses) and 88% of that on
the next round trip, etc... ]

That will only be true IF the Tx output stage has an infinite SWR looking
back in to it, AND the reflection is in phase with the forward signal. In
practice this will not happen. In fact the re-reflected signal may be
180degrees out of phase and so diminish the signal by its total value. The
real story is that a much smaller proportion of the reflected signal will be
re-reflected and the phase will depend on the system in use.

In reality the impedance of a transistor o/p stage looking back in will not
be too far away from 50 ohms due to the broadband matching networks.Some
transmitters that I have worked on even had a spec on the impedance looking
back in, a real pain to measure under full power conditions.

73
Jeff