You should enter your exact address instead of just a zip code. Or, better yet, use the interactive maps tool
here so you can see exactly what point is being analyzed. Switch to "hybrid" view, zoom in, and reposition the orange marker until it's right on top of your house.
If you enter just your zip code, it will pick some arbitrary point in your area to analyze. If it happens to pick a point on top of a mountain, then it will look like TV signals are all around.
An analysis of your exact location will yield more realistic results.