The most common, and easiest, solution is to add a Cable TV ground isolator.
Jensen Transformers has been around for over 30 years and makes one of the best (MSRP $59.95) as it has a flat frequency response from 2MHz - 1300 MHz, spanning the VHF/FM/UHF/CATV spectrum. Why is this important? Well for starters if you plan on using digital cable, a cable modem, or on-demand services you better not get a cheap RF filter from the local electronics store as it will most likely filter out more than you bargained for. In addition, we respect a company who measures their products and is willing to post a frequency response performance graph to back up their claims. Getting a flat frequency response from 2MHz - 1300MHz ensures no loss of signal quality and a great result.