Home Depot or Lowes usually has the ANT751. It is a very popular antenna for local reception. . A device in the house can generate interference , a computer that is on all the time , a flouresent light , a clock radio , a radio , one of the many little power transformers that are plugged into the outlets , just about any device. Unplug them all and turn off switches , one buy one and see if that clears the interference. Also the cell phone towers and electrical power generation can cause interference. A way to find out what is causing the problem is a , Spectrum Analyzer. The big Tv stations have Spectrum Analyzers that they use to go out into the field , ( to homes and business ) and out in the field to check the signals that are transmitted and received. You can call WRLH-DT 26 FOX , ask to talk with the engineering department ,
http://en.wikipedia.org/wiki/WRLH-TV ,
http://www.foxrichmond.com