Do Aerial Signal Boosters & TV Amplifiers Work?

March 11, 2022
Tom Smart

Do Aerial Signal Boosters & TV Amplifiers Work?


To answer the simple question above yes. That’s’ it, end of the blog… Ok just kidding.


The question shouldn’t be, do TV aerial amplifiers work? But will installing an amplifier or booster improve your TV aerial or Freeview signal? The short answer to that is that it might, it might not. For the long answer, which should help you identify whether you need a TV aerial amplifier or signal “booster” carry on reading.


You may hear “amplifiers don’t work”, which is wrong. They do absolutely work when used in the correct time and place. Large communal TV systems and systems connected to lots of TV’s will depend on amplifiers to boost the signal, so it can be distributed to many TV’s, not uncommon homes in today’s world with TV’s in most rooms. If you have found yourself on this blog becasue you are currently experinecing poor TV reception, please read our other blog on why your TV picture pixelates.


How Do TV Aerial Amplifiers Work?


Although there are numerous types, makes and models on the market. TV aerial amplifiers work on the simple process that you insert a signal into an input and a stronger signal will leave out of the output, or a signal that is less weak than it otherwise would be for when your aerial amplifier also provides signal splitting facility – for multiple TV’s.


When you introduce an aerial amplifier or booster into your TV aerial system it is worth noting that you do not get something for nothing, when you amplify the signal that you want to make stronger you will also inadvertently amplify a lot of things that you don’t necessarily want to make stronger. Like electrical noise, interference and signals from other nearby transmitters. So, amplifiers should never be added to a TV aerial system just for the sake of it as more often that not you would be better off not having one.


Cheaper models and manufacturers, that unfortunately are the only ones available in most DIY stores will often have such a large noise figure that it can cancel out the signal gain of the amplifier itself. Where possible try to purchase amplifiers from reputable manufacturers and play close attention to the noise figure. We can recommend manufacturers like Vision, Antiference, Triax, Televes & Wolsey.


When Is It A Good Idea to Install an Aerial Booster?


It may seem from the above that was not condoning the use of amplifiers, which I’m not. Amplifiers can play a vital role in keeping signals at an acceptable strength through out a TV aerial system. I was simply saying that there is a time and a place for aerial amplifiers and signal boosters and plugging one in on a TV that is suffering from poor TV reception Isn’t going to miraculously create a reliable signal. If it did, that’s all aerial installers and engineers across the county would do. It is certainly a lot easier to do that than crawl across roofs, up ladders and through lofts.


An amplifier cannot create a signal where there otherwise was none, and it cannot simply make an un-reliable signal, reliable. Amplifiers should only be added to a TV system to over come signal losses associated with the resistance on coaxial cabling and losses that occurring due to the splitting of TV signals to multiple TV’s. So, if you have an otherwise good signal coming off your aerial and owing to cable length or cable type this was being lost on the coaxial cable before it reached your TV set. Then a TV aerial amplifier would help, but it would depend greatly where you installed the TV signal amplifier. Here is a working scenario with TV signal strengths, it is worth noting that the minimum suggested signal strength for Freeview reception is 50dB, ideally at least 55dB in my opinion. You absolutely should never let a signal drop beneath 45dB for reliable TV reception:


Scenario 1: Amplifier installed behind TV set. (The Wrong Way)


TV Aerial = 60dB

Coaxial Cable, Signal Losses -25dB = 35dB

TV Aerial Amplifier + 15dB = 50dB


In this scenario, the TV signal booster has been installed behind the TV set. The aerial itself was delivering a good signal strength of 60dB. For whatever reason the connecting cable between the TV aerial and the television receiver was losing an exception amount of signal, which is not un-common for very long cable runs, cables that are in poor condition or single screened coaxial cables and as a result the 60dB signal that was leaving the aerial is now 35dB at the TV. A TV aerial amplifier has been installed behind the TV which itself has a gain of 15dB, which gives an acceptable 50dB signal strength.


Scenario 2: Amplifier Installed Near Aerial. (The Right Way)


TV Aerial = 60dB

Short cable length signal losses - 2dB =58dB

TV aerial amplifier + 15dB = 73dB

Coaxial Cable, signal losses – 23dB = 50dB


In scenario 2 a signal booster has been installed near the aerial end of the TV system. You can see that with method the signal has been amplified before it has been allowed drop below the minimum strength or before it come weak. This method would far trump scenario 1, in terms of TV reception and performance as you are carrying almost all the signal from the aerial throughout the TV system, which cannot be replicated in an amplifier. Whereas in scenario you would only be carrying 35dB of signal onto your TV. However, where a signal which is too weak is entering a TV, an amplifier would make the signal slightly better. This is because the TV’s, themselves add their own noise figure to the signal as the process it and sending it in stronger, albeit the wrong way will help it drive through all the TV’s parts and components.


Scenario 3 however which I haven’t given an example of, would be to find out why the cable is losing 25dB down it. A good quality coaxial cable should only lose around to 1db-1.5dB every 10 metres. If you are losing more than this, you should look at replacing your connecting downlead, wall plates and fly-leads which could explain the signal losses.


Signal Amplifier to Over-Come Splitting Losses


Where multiple TV’s are connected to a single aerial, there will be signal losses in the splitting of the TV signal. Unless you are physically disconnecting one TV to connect another it doesn’t matter if all the TV’s are on at the same time or not, you will lose signal each time you split the signal. This would be a perfect time to introduce a TV aerial amplifier.


Here are the associated losses with good quality passive signal splitters on frequencies used by TV and Freeview (UHF - 470-806Mhz) Please note that there are other factors that could affect how much signal you lose in a splitter, like quality of the splitter and temperature:


2 Way Splitter - 4dB

3 Way Splitter - 6dB

4 Way Splitter - 8dB

6 Way Splitter - 10dB

8 Way Splitter - 12dB


When doing your calculations, it is always best to err on the side of caution, so I recommend adding a few dB to each of these losses so you have a little room for movement on your signal levels. Here is another scenario with a splitter introduced.

If you would like to know more about how many TV's can you feed off a single TV aerial please click the link below.


Scenario 3 - Distributing A TV Signal To 8 TV’s (Wrong Way)


TV Aerial – 55dB

Short Coaxial Cable, signal loss - 1dB = 54dB

8 Way Splitter, signal loss - 12dB = 42dB

Coaxial Cable To TV, signal loss - 2dB = 40dB


You can see from the above, that the signal that was otherwise fine from the aerial to feed two TV’s with coaxial cables of similar, length, condition and quality. The introduction of an 8-way splitter to feed the amount of TV points required was directly responsible for the weak TV signal which would most likely result in poor TV reception.


Scenario 4 - Distributing A TV Signal To 8 TV’s (Right Way)


TV Aerial – 55dB

Short Coaxial Cable, signal loss – 1dB = 54dB

TV Aerial Amplifier – Signal Gain +15dB = 69dB

8 Way Splitter – Signal Loss -12dB = 57dB

Coaxial Cable To TV, Signal Loss -2dB =55dB


Done the correct way. A stage of amplification has been added before the signal losses associated with the 8-way splitter. This has overcome it completely and there is more signal gain on the amplifier than there are signal losses on splitter. This doesn’t always need to be the case, only so that the signal isn’t allowed to drop beneath the minimum. As a result, the TV now has more than enough signal to offer a good reliable reception.


There are amplifiers widely available which provide both the signal splitting and amplifying operations. These are called distribution amplifiers. Although it wouldn’t necessarily offer any more a reliable signal doing it this way. It would typically create a neater installation.


Installing Amplifiers at The Aerial Side of TV System (Head End)


One of the obvious drawbacks of installing a TV aerial amplifier is that a power supply will be needed near the aerial. This is fine where there is a mains electrical point in the loft as it is only typically a short length of coaxial cable that would connect an amplifier in a loft to a aerial on a chimney, or a aerial on a wall. The aerial itself may even be in the loft. In which case this would be perfect. However, it is not typically common to have a mains power socket with a loft. In which case, you contact a local electrician to come and install one for you which would obviously cost you more money.


A more suitable option though and one the TV aerial installer could do for you and without the need for a qualified electrician is to install a line powered amplifier instead of a mains amplifier. A line amplifier, more commonly referred to the most common type of line amplifier, a “masthead amplifier” is supplied its power directly from the same coaxial cable that feeds the TV. A small power supply unit or PSU is installed onto the aerial cable and a DC voltage, usually 5V-12V is sent up to the masthead amplifier on the coaxial cable allowing it to boost the signal.


The benefits of a masthead amplifier over a traditional mains amplifier is no mains power is required at the amplifier position, the masthead amplifier itself can be sited very close to the aerial itself, most common on the aerial mast and comes in a weatherproof outside box, hence the name. This allows the signal to be amplified whilst it is still at its strongest carrying the maximum amount of genuine signal throughout your TV systems. Here is a video guide on how to install a masthead amplifier.


Problems with Signal Boosters


I have identified some issues with TV aerial amplifiers and potential problems they could cause with your TV reception. More information on why your TV pixelates can be found here.


Too Much Signal


Believe it or not this is a genuine problem, when a signal goes beyond a certain signal strength it can overload equipment which can cause the TV signal to lose signal, become blocky and suffer from pixilation. Every piece of aerial equipment will have its maximum signal strength handling capabilities. You should however not send a signal of more than 80dB into a TV. Launch amplifiers which are used on communal TV systems can often handle signals of up to 120dB which translates to 1V.


Amplifying Of The Wrong Signals


The vast majority of amplifiers will not be able to distinguish or are programmable to only amply the signals you want and the ones that can are extremely expensive. It really does depend on what part of the country you are geographically located but often when a TV aerial has been installed, and no band pass filtering has been installed. The aerial could be picking up signals from multiple transmitters, whilst this might not be a problem when you run an auto-scan on your TV it may store the TV services from the transmitter which itself may be unreliable and cause signal loss of picture pixilation. To avoid this, I recommend installing filters to remove unwanted signals and manual tuning your TV instead of performing an auto-scan


Another common scenario is when interference is amplified, like 4G, 5G, tetra and when it otherwise was not at a strength where it would cause poor TV reception the boosting or amplifying of the signal has caused it to become too strong.


More to Go Wrong


Simply having an amplifier in your system increases the likelihood of complete TV system breakdown for many reasons. The main reason being that electrical occasionally does go faulty from time to time, so a TV aerial system with no amplification and passive splitters instead of distribution amplifiers would be less likely to go wrong. There is the other obvious example if accidental misuse, where a TV aerial amplifier or power supply unit (very common) has been disconnected causing complete loss if of TV reception.


Frequency Band – On Board Filtering Issues


Whilst the on-board filtering additions are a great advancement, you can potentially install a TV aerial amplifier that can as well as boost a TV signal and increase the strength, filter out common interference sources like 4G, 5G, Tetra etc. Problems start when the amplifiers filter out signals you want to keep. An example of this would be where we are in East Sussex, the Brighton transmitter at Whitehawk Hill uses the UHF channel 60 for its BBC services. Some amplifiers these days, not all but some will filter down to channel 58 so it can effectively remove 4G interference which begins at channel 61. This would in fact reduce the reliability of the BBC services and could even result in losing them altogether.


Another common situation where amplifiers are filtering out services we wish to keep, is with Sky playback systems. Sky boxes by default are factory programmed to output on UHF channel 68. You could be in a situation where an amplifier has gone faulty, so you replace it and in doing so filter out your Sky playback signal. This is easily solved by moving the Sky RF that the Sky box uses.


Conclusion – Aerial Amplifiers Do Work


To conclude, if you were still in any doubt at this point. TV aerial amplifiers and signal boosters do work. They can help overcome signal losses because of cable resistance and because of the splitting of signals to multiple TV’s.


They won’t however miraculously convert a poor or weak TV signal, into a good reliable signal. But when used right they can fix your signal issues.


It’s better where possible to fix your TV aerial reception passively, without amplification where possible. So, replacing aerials, aligning for peak reception or relocating them to better positions, perhaps from the loft to the roof would be a better option. Also, only using the highest good quality double screened coaxial cable and screened wall plates and high-quality fly leads would be a better solution where possible than bringing in unnecessary amplification.


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Until next time



Home Entertainment & Connectivity Specialist

Aerial & Satellite Extraordinaire

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