Mount the yagi above the roof aimed at about 50 degree magnetic compass.
The 2 antenna systems Will Not be connected to gather on to one coax.
The 2 antenna systems will be separate all the way to the Tv location/s and be connected to a A/B antenna switch ,
http://www.radioshack.com , #15-1968 , or ,
http://www.mcmelectronics.com , # 32-4425 .