A few different factors can cause bad—or no—reception when using a TV antenna. The first thing you should check is if your antenna is properly installed. Grab your manual and go over the steps again.
The following factors can also cause poor reception or signal degradation:
Your coaxial cable is longer than 100 feet
Splitters
Nearby electronic appliances or topographical obstacles (buildings, hills, mountains, etc.)
Insufficient antenna range (brand-advertised ranges can be inaccurate)
Bad antenna placement
A defective unit