snip

10 or 12 db of forward gain means your recieved signal is about 10 to 16
times as strong as a dipole hanging in the air. If you interpret the
negative number as the amount the signal is down from the forward gain,
the numbers given (9 to 17db) would indicate reception off the back side
would be somewhere near a dipole in open space (1 db net) to -5db (about
1/3 of the signal of a dipole) pickup from the back. I have used aluminum
sheet (tested prior with aluminum foil) tied to the mesh to completely
block reception from the back (a near infinite front to back ratio) in an
extreme case where I had significant multipath reflections coming in from
the back. It really cleaned things up. In your case you may not need to
go to this rather severe step.

snip

Good luck!
--Rick AH7H

10 or 12db of forward gain goes NOT equal 10 "times" the received signal
strength.