Ramsey Electronics WSR-ANT Assembly And Instruction Manual page 16

Mounting on a chimney
This is the simplest of methods, as you will need 2, 1 1/2" pipe
brackets (plated metal preferably), 4 self tapping machine screws,
and some plastic anchors.
First line up the antenna with the chimney. If the upper portion of
the chimney is larger than the lower, you may need to mount a
block of wood at the base to make the antenna mast plumb.
Drill the appropriate holes in the chimney for mounting, and then
insert the plastic anchors. Now you can screw the machine screws
into the plastic anchors with the antenna in place.
WSR-ANT • 16