If you are thinking about installing a television antenna for your home to get free over the air HD Television then you have a variety of choices that you have to make to build your system.
The first and most important choice is the selection of your television antenna. Without a quality and correctly sized antenna you will never be able to pickup stations that are local or far away.
When you select the correct antenna for your location you will want to find out what power it is rated at in dB or decibels. Then you will want to calculate the impedance level of the wire and splitters that get that signal from the Antenna to your television. Impedance is resistance of signal to pass through a wire or device.
For instance if you have a single antenna and 4 televisions in your home you will need a piece of coax wire from the antenna in your attic or on your roof down to a splitter which will allow you to attach independent lines for each television.
The longer the wire from the antenna to the farthest tv the higher the impedance and because coax cable is rated for impedance it is easy to calculate the effect it will have on your signal.
The same is true for every splitter that comes between the antenna and a television. Each splitter should have a rating on dB loss from the Input to the Output and there are lower quality splitters that can introduce more signal loss so you want to purchase a splitter of good quality. Consider the fact you will only be buying this once if you get it right the first time. Also if you are reusing splitters from your cable tv install make sure they are of good quality.
Once you know the amount of signal loss from the antenna to your television you are ready to consider the size of the amplifier that you will need.
There are two types of amplifiers that you can choose to use however the best performer will be a pre-amplifier. A pre-amplifier is connected at the output on the antenna before the coax cable is connected. It pushes the signal through out the system.
The second type is a distribution amplifier which can also benefit your system if you find you have good signal off the roof and into your home but are losing signal due to your splitters.
A distribution amplifier will not normally improve signal quality as much as a pre-amplifier and that is why people go through all the trouble of installing one on the antenna mast before it enters your home.
What size television antenna amplifier will you need?
The first thing you want to do is measure the longest distance of cable in the home and calculate the dB loss.
For every 100 feet of RG6 Coax cable you will lose 6dB of signal.
For every 100 feet of RG59 Coax cable you will lose 10dB of signal.
Splitters should be checked for their actual rating however in general. Remember even if all the ports are not used the splitter will still cause the same amount of signal loss so it is always best to go with splitters of the fewest ports and use the fewest splitters that you can.
Splitter Loss
2-Way Splitter 4dB
3-Way or 4-Way Splitter 8dB
8-Way Splitter 12dB
Calculate the loss to the farthest television by adding up the dB loss from the cable and the splitters.
So, if you have 50 feet of cable into your house to the first splitter and then 50 feet more to the farthest television that is 6dB loss.
Then if you split the signal with a 4 way splitter you will have 8dB loss.
The total loss from cable and splitters is 14dB.
That means at the very minimum you will want a 14dB pre-amplifier to overcome the impedance of your distribution system.
To improve the signal you will need a larger amplifier and you can purchase amplifiers that will increase the output signal about 30dB.
Well thats great then why aren’t they all 30dB amplifiers because we all want the best signal.
The higher you amplify a signal the more noise that you will introduce.
The way this works is …. lets say you have two competing signals in your area. One might be Channel 27 UHF and the other might be a Local FM Radio Station. These signals should not overlap however in reality you could find that the FM station that is Local blocks part of the TV Signal that is Distant.
There are often options to filter out FM Signals on Amplifiers but some people also like to use their Antenna for FM Reception.
Whatever the problem or dirty signal is you will make it louder. This is why its normally better to go with a Larger Antenna and a smaller Amplifier for best signal quality.
What are Distribution Amplifiers?
A Distribution Amplifier is normally installed in place of a splitter or it can be used to amplify signal to televisions that are outside of your normal range.
If you had a Television in your detached garage apartment that might be a good reason for using a distribution amplifier. Another might be an apartment building or business.
A distribution Amplifier takes good signal and pushes it along its path to overcome the problem of cable impedance and splitting.
That means you would use a pre-amplifier to get the signal into the building and a distribution amplifier to overcome any distance or splitting problems.
Distribution amplifiers normally introduce noise more than pre-amplifiers but it is good to remember both will introduce noise to a bare signal.
Final Note
I hope this how to on Antenna Amplifiers helps you understand how to select the correct amplifier for your home or maybe your business.
Amplifiers will not overcome the absence of signal but they can improve signal quality.
In years past noise was a serious problem from amplifiers and you would often have signal problems with analog stations overlapping more than we do today with Digital Amplifiers. However the practice of relying on an amplifier should come with the reality that one day this device will need replacing.
If possible you always want to buy the largest antenna that you can so that you get quality original signal and hopefully if you are close enough to your broadcast towers you might not even need an amplifier except on the very worst rainy days.
On the other hand if you are very distant than an Amplifier mounted on the largest antenna you can find may mean the difference of receiving signal or not receiving signal so do your research and find out how strong in dB’s your system must be then calculate the loss when you split it out to more televisions.