The problem is that unless you're within a couple of miles of the transmitting towers, you usually have to direct your antenna towards the towers. And the odds are your dish isn't oriented this way (not to mention that such antennas don't have the proper design for UHF signals).
Two good brand names to look at are Channel Master and Winegard. For the CM's, two good antennas are the 4221 and the 4228. The '21 is smaller and less receptive than the '28, but is less directional, too. Also, note the old adage that every 10 feet in height over the top of your house more or less doubles your signal.
For an inside antenna, try the Silver Sensor antenna from Zenith. If you're within 5-10 miles of the transmitting towers, you may have good luck with this.