Why Are Television Aerials Installed On Roofs?

Have you ever wondered why TV aerials are installed on chimney stacks, high up on walls on large aerial masts, and roofs? If you have, then read through this article & here at TV Aerials St.Helens we will tell you why.

Unlike satellite dishes, which are designed to receive signals from satellites located high up in space, radio and TV aerials both receive signals from transmitters based on land. A majority of land-based structures like buildings and trees that sit between the transmitter and your antenna could block transmitter signals from reaching your aerial, well unless you live near a TV or radio transmitter – in which case all you might need is an aloft or indoor aerial. However, that is often not the case, and you might find it necessary to install a TV aerial on an aerial pole or chimney stack outside your property.

Installing an Aerial at an Elevated Point Outside Your Property Maximises Signal Strength

By installing your aerial outside, you maximise its capability to receive a stronger reception without too many obstructions, lowering its chances of pixelating or breaking up. TV aerials are typically installed on rooftops or high places to eliminate or reduce the chances of obstacles such as buildings and trees blocking the signal being broadcast by transmitters, considerably enhancing reception. If, where you are installing your aerial, there’s a line of sight between the TV transmitter and your antenna, then you should be able to get a reliable signal. Plus, aligning your aerial will most likely be very easy for you – all you will need to do is to point your aerial to the transmitter, and that is it. No need for special aerial aligning tools!

While it’s recommended to install your television antenna outside, it is advisable that you be very cautious when doing so since there is a chance you could overload your distribution equipment and TV tuners with too much signal if you reside in an area with strong signals. One way to avoid this is by using an attenuator. Alternatively, instead of using a high gain aerial, you could also go for something like a log-periodic aerial.

Having your aerial installed high up on your house will help maximise signal strength. At the same time, it will reduce the need for a TV aerial amplifier if you have multiple television points – passive splitters should work just fine. When your aerial is installed in a location where the signal is strongest, you can afford to lose a bit of signal through passive splitters.

Every Extra Decibel of Signal You Receive Will Create a More Robust/Reliable Signal

If you understand satellite, terrestrial radio, and TV aerial signals and know how they are measured, then you know the notion behind this comment. If you do not, then here is a quick brief on signal strengths.

Aerial signal strength is generally measured in dB – decibels – in regards to microvolts. When it comes to digital TV signals like those used for Freeview, the absolute minimum is 40 decibels; however, aim to receive no less than 45 decibels. If you receive less than this value, consider installing your aerial higher up your property or on a giant aerial pole to elevate it to a position where the signal is strongest. You should also consider installing a masthead amplifier or a high gain aerial. This will help boost your signal, making it easier to overcome the loss of signal associated with connecting coaxial cables.

Signal strength is only one of the things that you should be concerned about when installing an aerial. The other thing to consider is carrier-to-noise or signal-to-noise. This is the relation between the signal received and the noise within the signal. For instance, your aerial could be receiving a decent 60 decibels of signal strength but with an interfering signal of 40 decibels on the received frequency – that means that you only have a signal strength of 20 decibels, which isn’t good at all. This is what is known as the carrier-to-noise ratio.

While all equipment measure this, albeit differently, it is recommended that you pay close attention to your equipment’s MER (Modulation Error Ratio) if it has it. This will allow you to look at the signal itself and will give you useful measurable information. I will be discussing this more comprehensively in a later blog, so that is all on this matter for now. However, theoretically speaking, every extra decibel your television receives from your aerial will most likely be added to the carrier-to-noise ratio, leading to a strong, robust and more reliable signal.