|by "placed where it can get signal" means about half way between the barn and house. Not exactly practical.|
Depends on the router. My router covers my house, yard, and down the street. 75 feet is not that far. You get what you pay for when it comes to routers.
What you need are directional antennas, one on the house and one on the barn [pointing at each other].
Oh yeah,...that'll look GREAT! Pricey too!
Or run a cat5e/6 network cable from router to barn. This maybe the better way of going.