HDTV Reception:

An HDTV antenna system is very critical, and should use a HIGHLY DIRECTIONAL ANTENNA designed for "Fringe Area" reception.  Your objective is to pick up the signal directly from the transmitting tower, without picking up signals bouncing off of buildings, electrical transmission towers and wires, et.  This is the design goal of a "Fringe Area" antennas: to reject signals coming from any direction other than straight ahead.   You should avoid using an antenna mounted amplifier.  These amplify everything, including the nearest telephone cell site. Mount the antenna away from all reflective surfaces or other antennas, and as high as possible.   

The Federal Communications Commission guarantees you the right to install a TV antenna, even if local zoning codes or "Condo Associations" forbid it.  

Buy a rotator for your antenna if the stations you are trying to pick up are more than 30 degrees apart.  If you live less than 5 miles from the station, you may have to buy a 10 or 20 db attenuator to reduce the signal to a level that will not overload your HDTV set.

One of the most common causes for poor reception is strong signals from FM radio and TV stations.  An FM TRAP (filter that remove FM stations) is sometimes necessary.   Your antenna brings in the whole broadcast spectrum, and this can overwhelm a receiver, just like a camera's flash "blinds" your eyes.  Too high a signal is just as bad as too little.  Remember: your antenna delivers ALL TV and FM stations to your DTV tuner at once. 

Seal all outdoor connections, especially at the antenna, with a product called "coax seal."  If none is available, use RTV.   Humidity in the atmosphere is your worst enemy, and can form water droplets and corrode your connections.  

If you have multiple TV's, and cannot put up a separate HDTV antenna:

IF ALL THE TRANSMITTING TV STATIONS ARE IN THE SAME DIRECTION and you have multiple TV sets and splitters, replace the splitters with a good MATV Antenna Amplifier with multiple outlets - one for each TV, and buy and install a termination for any output you don't use on the MATV amplifier.  Place this MATV amplifier as close to the antenna as possible, in the attic, and make your runs to each TV from there.  

The purpose of this MATV amplifier is NOT to provide as much signal as possible to your HDTV set.  TOO HIGH A SIGNAL WILL MAKE YOUR HDTV SET USELESS (pixelate). The purpose of this amplifier is to provide ISOLATION from each of the other TV sets and their cable runs.  

Thing to consider:

• An HDTV antenna should be thought of as a spotlight in reverse; it should pick up a signal from only ONE direction, and reject all other incoming angles of the same signal (reflections) bouncing off of  buildings, towers, et.  This bouncing is known in RF terms as multipath, and shows up as as a "ghost" or "smear" to the right of the image. 
  
  
• Don't try to "split the difference" when pointing your antenna between two digital stations coming from different directions.  If they're more than 30 degrees apart, use a rotor, or separate  antennas.
   
  
• When using separate antennas, DON'T MOUNT VHF ANTENNAS (channels 2-6) ON THE SAME MAST, unless they have a 10 foot or more vertical separation, and 6 foot or more vertical separation for channels 7-13).   UHF yagi-style antennas can usually be mounted with about a 4 foot vertical separation.  If you are going to combine signals so that you have only one lead going into your house, use a channel filter for each antenna, so as not to pick up out-of phase signals or multipath through the other antenna.  Then and only then you may combine the signals through a combiner (a kind of "splitter" in reverse).
  
  
• IF YOU LIVE CLOSE TO AN HDTV STATION, you may have to install an ATTENUATOR to REDUCE the strength of the signal to a level that is useable by your HDTV receiving equipment. This is the equivalent of wearing sunglasses in bright sunlight.
  
  
• Do NOT use a 300 ohm antenna system.  Replace it with a 
  Highly Directional Antenna System, designed for a fully 
  shielded, Coaxial Cable antenna lead to your receiver.
  
  
• If you insist on using a 300 ohm antenna, use a "BALUN" to convert the 300 ohm impedance of the antenna to 72 ohms to match the impedance of the coaxial cable going to your TV set.  Then use 72 ohm, 100% shielded coaxial line to the TV or PC Card. 
  
  
• If you MUST use 300 ohm line, TWIST it 2-3 turns per foot
  to prevent it from picking up signals directly (multipath). 
  
  
• AVOID USING AN ANTENNA WITH A BUILT-IN
  PREAMP, unless you are far away from any transmitter,
  including FM, 2-way radio, and especially cell towers.
  
  
• YOU MUST TERMINATE ALL UNUSED RF AND VIDEO
  coax lines from splitters and distribution amplifiers.  
  If you don't have a TV connected to a TV outlet jack in another room,  install an RF Termination.
  Failure to do so could cause the reflected signal to corrupt
  the data stream, and may cause your signal to  "freeze" 
  for no apparent reason, or with the  slightest bit of 
  additional multipath or interference.
  
  
• If you install a system near a Radio, FM, HAM, Cell Phone, or other tower, or other source of radiation, INCLUDING SOME MICROWAVE OVENS, use a TV-Bandpass Filter between your TV antenna and your TV receiver.
  
  
• There are many potential causes of emissions (unwanted RF or interference) that might prevent you from receiving HDTV, or cause your HDTV picture to "FREEZE."  Most can be detected by a portable AM RADIO, that is NOT tuned to any station, just static.   Listen for an INCREASE IN STATIC or  "CLICKING" Noise as you go from room to room, or towards a suspected source.  This is how I found RF interference coming from my SONY Weather Radio.  Every time the green fluorescent light on the front panel flashed, a burst of RF (Radio Frequency(s)) was emitted.  Other sources of Digital Television Interference  include, but are not limited to:

1. Power distribution grids that emit  "static," especially poles with  lightning arrestor banks.
2. Power distribution grids that emit  "static" caused by  .
3. Ignition "noise" from parked or passing cars, motorcycles, lawnmowers, et.
4. Portable home telephones, Cell Phones, and (digital) 2-way radio equipment
5. Starting circuits on motors, pumps, and air conditioners.
6. RF emissions from fax machines, computers, "screw-in" type florescent lamps with electronic ballasts, and even some battery charges for laptops, camcorders, et.
7. Home and industrial lighting dimmers
8. Appliances, including other TV's
9. Battery operated Tools (drills especially) and Toys
10. Common tube-type florescent lamps, especially towards the end of their life when they "flicker"