The OTA= Over The Air , Digital Broadcast Tv stations/channels.
Are Weak Signal Strength at your location.
Here is the Federal Antenna Law that says Yes a Tv antenna of Any Size can be installed Above the Roof in a manner that provides Reliable Reception.
Reliable reception - does not included - hiding the antenna - or using using a antenna that is so small that reliable reception will not happen.
http://www.fcc.gov/mb/facts/otard.html.
If you choose to install above the roof in a manner that provides Reliable Reception.
I will provide information of antenna and antenna system that will provide Reliable Reception of the Major Network Digital Broadcast Tv stations/channels. And many more Tv stations/channels will be received also along with the Major Networks because the Tv stations are there to receive.