The way that TV reception works has changed since the digital ready rollout. Previously we used analogue signals to transmit TV. Jumping up on the roof and simply moving the antenna from left to right would produce results. But now that we are using Digital signals it is not that easy.
A digital signal transmits data, and data is either on or off. Moving an antenna will either receive a signal or not. you will not see it improve or get worse as you move it. Further more, a signal can be both too low or too high.
To adjust a antenna, install a booster or a attenuator or simply adjust a booster or antenna you need a digital TV reception meter. A meter that does this correctly is many thousands of dollars and not something that you purchased from the hardware or on ebay.