I’ve tried several antennas for digital TV and have received the best signals using an inside flat WHITE antenna in an upper pane of a window facing the most transmitters. White, because the RCA black flat passive digital antenna I tried got very hot when the sun shone on it all afternoon. Feed your existing line amplifier and the whole house gets the same signal strength.
Most of the flat passive antennas I’ve tried get about the same reception as the amplified ones and the cheap ones work about as well as the more expensive ones. The secret is putting (tape or velcro tab) the WHITE antenna high in a window. I was amazed.
My recommendation is presently sold out online at Wal-Mart: RCA Digital Flat Passive Antenna Model # ANT1400 - $16.97
What exactly is an existing line amplifier?