Some Guidelines to improve Reception Quality
To receive HD signals via satellite or cable might be the best choice as far as image quality is concerned but there are thousands of possible individual situations where OTA (Over the Air) would be the only option. In this case you would need an OTA antenna to receive RF signals in HD format which come from an earthbound station and are transmitted through the atmosphere.
If this applies to you there are some rough guidelines which will help to make the best out of your OTA set up. But be aware that every location has it's own issues. Settings which work splendidly in Chicago, Illinois might not work at all in Phoenix, Arizona, not to talk about Quicksand, Kentucky. So if you adhered to all the following suggestions and still can't receive OTA HD signals or only in bad quality ask for help in a local TV shop or call your local TV station.
First and most important: You NEED an antenna and if you are at all serious about picture quality you need an OUTDOOR antenna! Unless there is a situation which absolutely makes installing an outdoor antenna impossible do not settle for an indoor antenna. And if you live more than 70 miles from the nearest transmitter an outdoor antenna is your only chance to receive a signal at all.
Unlike waves in the visible spectrum radio waves do penetrate barriers but there is a considerable loss in signal strength. The clearer the signal comes through to your antenna the better your reception will be. The same principle applies when it comes to the height in which you place your antenna. If you would perform a test you would recognize that your image quality improves when you place your antenna higher. The reason is that the wave has to go through less and less barriers travelling from the transmitter to your antenna. On lower levels it might get obstructed by houses, trees, lampposts etc.
Next to it's placement the antenna size is of major importance. The bigger the better. Antennas consist of several dipole elements. The distance between the two poles within one element should ideally be 1/2 of the signals wavelength. Channel 2 e.g. transmits on a 6 m wavelength which requires your antenna to measure at least 3 m in diameter. TV antennas contain several dipole elements with varying length to cover the whole range of broadcasted wavelengths.
Secondary Signals might pose a serious problem to a perfect reception of your HD signal. These come about by the wave being reflected by objects near the antenna. These reflections arrive at the antenna with a phase shift compared to the directly received signal which can lead to interferences with serious distortions of your TV image. If secondary signals are a problem in your area you might need a directional antenna which can receive signals only from one direction and is shielded from signals coming from other directions. The antenna has to point in the direction of the next transmitter. If different channels broadcast from different transmitters your antenna must be equipped with a motor to rotate it in another direction if you change channels.
If you have a nice big antenna and it's position the roof or balcony is relatively unobstructed, yet have a weak signal you can employ an amplifier. But make sure you really need it. If you receive an already strong signal and it is still passed through an amplifier your TV image might become distorted. If you live close to a transmitter station an amplifier is most probably not necessary.
There are different technical specifications to an amplifier which might be confusing. Most important is the amplification factor in db. Note that the db-figures indicate a logarithmic scale. 10 db means the signal is 10 x, 20 db means 100 x, 30 db means 1000 x amplification etc. High quality outdoor antennas should have db values of 15 - 20 or even higher. Then there is the noise figure. This should be a low number. If you compare different amplifiers brands, the one with the lower noise figure is of higher quality.
The distortion figure indicates how much the signal character is changed by the amplification process. The less the better, of course.
More advanced (and expensive) amplifiers even compensate for the technical fact that a signal of higher frequency loses more of it's strength when passing through a coax cable than one of lower frequency. This effect is is made up for by a higher boost of higher frequencies. If there is absolutely no way how you could mount an outdoor antenna you'll have to fall back on an INDOOR antenna. In this case testing is the best way to come to an optimum reception. This would include testing different OTA antenna brands (come to an agreement with your retail store that you can take several antennas home to test. Then buy the model which delivers the best picture and return the others) and different positions in the house. A possibility of placing it in the attic would definitely increase your chances of a good reception, even if it would require longer cable connections to your TV room. Also try different positions within the room. Put it somewhere away from the TV set, computers or other digital processors otherwise it might come to interference distortions.
If all fails, even after you have checked for local specialities, you still have cable and/or satellite dishes as alternatives.
Klaus Lehne has a university education in natural sciences. He has written several product reviews. Reviews on HDTV equipment and more HDTV consumer tipps can be found on http://www.hdtvplace.com
Source: www.articledashboard.com
