Find your attic access.
Ground wire in attic.
Strip away about 6 inches of outer insulation and 1 2 inch of individual insulation from the end of each wire.
Air movement in your attic should not pose a problem.
I found that a firm grounding of antenna mast gave a better reception as well.
Bare copper antenna wire stapled directly on wood rafters causes loss of rf signal energy.
Grounding of mounting hardware is not required indoors.
Use wire nuts to connect.
You have to inspect it along its full length until you reach a working ground wire.
With time bare copper oxidizes the wood where the wire is tightly stapled to absorbs some of this oxidization and forms a loose yet lossy bond with the wire.
Insert the end of the 12 2 wire into the fans junction box.
Measure the distance between the two sites you want to run wire between and make sure you will have enough wire.
You can use the outside of the electrical conduit provided the conduit has a continuous reliable electrical connection to earth ground.
Check to ensure that the vent tube is firmly grounded before connecting the wire.
Lets you do precisely what you are describing running a separate ground wire to an existing point on the equipment grounding system originating from the same panel.
The attic shortwave antenna wire this is the most importantaspect to improve.
How to run wire through an attic step 1.