New build tv aerial

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10monty

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My sister just moved into a new build, was told aerial all sorted but she only has cabling installed to rooms and it's all coiled in loft. They can't have an external aerial until the whole site is finished and handed over so I need to get an aerial fitted in the loft, and will move it outdoor if needs be when they're allowed.

I can do the work I'm just not up on latest aerial tech.
Am I ok just getting a high gain wide band aerial.
They are approx 30 - 35 miles as crow flies to nearest transmitter (according to the free view postcode checker)
Ta
 
Buying a high-gain wideband aerial could be likened to buying a really big hammer, and then missing the nail on every hit.

Have a look at the little graph below, ad then let's break down what high-gain wideband really means. The wideband part means that the aerial is designed to pick up all of the RF channels being transmitted. They're designed to pick up from RF ch21 to ch68.

The high-gain bit refers to the ability of the aerial to pull in signals. The coloured lines on this graph represent how good an aerial is at pulling in signal across the entire signal range. With a wideband aerial that's high-gain, would line A, B or C best represent the capabilities of such an aerial do you think?

Gain profile.jpg


You may have picked B. Most people would too.

Would you be surprised to learn though that line C is actually a closer match to the real gain profile? A so-called wideband high-gain aerial is only really high gain in the upper third of the ch21-68 range.

If you were tuned to a transmitter that bunched all its signals in the upper 1/3rd of the of the signal range then this wouldn't matter. The aerial would be a good match. But what if your local transmitter uses the middle third or even the lower third? This wonder aerial wouldn't perform quite so well in those situations.

A wideband high-gain aerial then is certainly wideband, but it's only high-gain in a very specific range, and that might not be a good match if your local transmitter doesn't use those frequencies.

What would happen if for some reason it was decided to shrink the transmitter frequency range so that channels 51 to 68 were no longer available?

Gain profile_2.jpg


This is exactly where we're heading right now. The WB H-G aerial is still wideband. It picks up ch21 to 50 which is the new range. But the bit where it was High-Gain has been lost. These aerials haven't yet been redesigned for the new transmission range.

This is why the garden-variety wideband high-gain aerial isn't a good choice. In fact, for many transmitters in the UK it was never a good choice. A smarter move is to look at the local transmitter and see where it has its transmissions. Give us the name of your local transmitter and we'll make some recommendations that are a better match.
 
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This is why i asked the question, I can fit and do the connections but not clued up on the technical side
 
I moved into a new build some years back, exactly the same scenario, I just pointed it in the same direction as the local existing houses were pointing.
 
Lucid said:
Buying a high-gain wideband aerial could be likened to buying a really big hammer, and then missing the nail on every hit.

Have a look at the little graph below, ad then let's break down what high-gain wideband really means. The wideband part means that the aerial is designed to pick up all of the RF channels being transmitted. They're designed to pick up from RF ch21 to ch68.

The high-gain bit refers to the ability of the aerial to pull in signals. The coloured lines on this graph represent how good an aerial is at pulling in signal across the entire signal range. With a wideband aerial that's high-gain, would line A, B or C best represent the capabilities of such an aerial do you think?

View attachment 269934

You may have picked B. Most people would too.

Would you be surprised to learn though that line C is actually a closer match to the real gain profile? A so-called wideband high-gain aerial is only really high gain in the upper third of the ch21-68 range.

If you were tuned to a transmitter that bunched all its signals in the upper 1/3rd of the of the signal range then this wouldn't matter. The aerial would be a good match. But what if your local transmitter uses the middle third or even the lower third? This wonder aerial wouldn't perform quite so well in those situations.

A wideband high-gain aerial then is certainly wideband, but it's only high-gain in a very specific range, and that might not be a good match if your local transmitter doesn't use those frequencies.

What would happen if for some reason it was decided to shrink the transmitter frequency range so that channels 51 to 68 were no longer available?

View attachment 269935

This is exactly where we're heading right now. The WB H-G aerial is still wideband. It picks up ch21 to 50 which is the new range. But the bit where it was High-Gain has been lost. These aerials haven't yet been redesigned for the new transmission range.

This is why the garden-variety wideband high-gain aerial isn't a good choice. In fact, for many transmitters in the UK it was never a good choice. A smarter move is to look at the local transmitter and see where it has its transmissions. Give us the name of your local transmitter and we'll make some recommendations that are a better match.
Click to expand...

The house is in pe6 0gu although this doesn't show up so Ive used pe6 0ep which is the street behind.
It's showing as Waltham being the nearest transmitter
 
Lucid said:
Buying a high-gain wideband aerial could be likened to buying a really big hammer, and then missing the nail on every hit.

Have a look at the little graph below, ad then let's break down what high-gain wideband really means. The wideband part means that the aerial is designed to pick up all of the RF channels being transmitted. They're designed to pick up from RF ch21 to ch68.

The high-gain bit refers to the ability of the aerial to pull in signals. The coloured lines on this graph represent how good an aerial is at pulling in signal across the entire signal range. With a wideband aerial that's high-gain, would line A, B or C best represent the capabilities of such an aerial do you think?

View attachment 269934

You may have picked B. Most people would too.

Would you be surprised to learn though that line C is actually a closer match to the real gain profile? A so-called wideband high-gain aerial is only really high gain in the upper third of the ch21-68 range.

If you were tuned to a transmitter that bunched all its signals in the upper 1/3rd of the of the signal range then this wouldn't matter. The aerial would be a good match. But what if your local transmitter uses the middle third or even the lower third? This wonder aerial wouldn't perform quite so well in those situations.

A wideband high-gain aerial then is certainly wideband, but it's only high-gain in a very specific range, and that might not be a good match if your local transmitter doesn't use those frequencies.

What would happen if for some reason it was decided to shrink the transmitter frequency range so that channels 51 to 68 were no longer available?

View attachment 269935

This is exactly where we're heading right now. The WB H-G aerial is still wideband. It picks up ch21 to 50 which is the new range. But the bit where it was High-Gain has been lost. These aerials haven't yet been redesigned for the new transmission range.

This is why the garden-variety wideband high-gain aerial isn't a good choice. In fact, for many transmitters in the UK it was never a good choice. A smarter move is to look at the local transmitter and see where it has its transmissions. Give us the name of your local transmitter and we'll make some recommendations that are a better match.
Click to expand...
Everything perfectly clear...
Bag of ice over my head now...:ROFLMAO::ROFLMAO::ROFLMAO:
:whistle::whistle::whistle:
 
Hi, these are the experts, a group A aerial is recommended:

Waltham Transmitter - A.T.V. Poles, Brackets, Clamps & Aerials (aerialsandtv.com)

Being a main transmitter Waltham is horizontally polarised and puts out (up to) 50kW. Originally, for analogue it was a C/D group but with the advent of digital television it went wideband, before, in Mar 2020, becoming an A group. For those in reasonable signal areas (= most people) it will make no difference, but for those in poor signal areas swapping to an A group aerial will give a significant increase in signal (if you have an A group aerial obviously), see Waltham’s graph.
Waltham has has sixteen [including Nottingham] smaller repeaters to improve its coverage in poor signal areas.

There is one “Local” MUX allocated to Waltham (on CH26 to the 3rd March and on CH41 after that) which is mainly used for a local Nottingham TV station.

For Waltham we recommend we recommend the DM log or Yagi10K for strong signal areas, the Log36 or Yagi 18K for medium signal areas, the Yagi18A* for outside installs in poor signal areas, the XB10A* for loft installations in poor signal areas, and the XB16A* for those with the most marginal signals. Unless you have a massive loft we’d normally recommend the XB10A over the XB16A for a loft install due the smaller size of the former aerial. The dimensions and test performance of the aerials can be found on the relevant buy pages.
 
This isn't my local area, but online sources suggest that Waltham currently uses RF channels between 29 and 55. However, RF ch55 is temporary. Once the final reshuffle and channel moves are done then it will disappear. It looks like the range will be RF ch29-48 after that.

There's a signal level predictor site called Wolfbane. It's possibly a little out of date now, but if you take the results with a pinch of salt then the suggestion is that Waltham to Crowland gives something like a 45dB field strength. What that says to me as an installer is that I should be prepared for a fairly weak signal in the general area. The caveat here though is that Wolfbane can't predict the results for a specific address. Local conditions have too big an effect. A house with a bit of extra elevation, or somewhere flat with no line-of-sight obstructions could help. The flip side could be a loft mounting with the aerial effectively point through some other buildings too which would reduce the signal even further.

45dB is what I'd consider to be the lowest threshold of signal at the TV aerial socket after any loses from cables and connections have been factored in. Ideally though I'd be looking for something in the 50-55dB range.

For a roof mounted aerial on the end of say 15m of cable, then the system losses would amount to around 3-4dB, so I'm looking for the aerial to generate between 53 and 59 dB to get 50-55dB at the TV end. With a loft installation then I know I'm see a further reduction in signal level by about 3dB in the dry and anything up to 6dB when the roof is wet.

Pulling this all together, you're either going to have to get an exceptionally high-gain aerial to make up the signal level shortfall, or be prepared to add some amplification. When the aerial moves from indoor to outdoor then you may find that it's not needed, or at least not as much, and so some kind of amp with an adjustable level control for gain would be a sensible move. This does all hinge though on whether real life follows the model prediction. I can tell you right now, it doesn't always work that way.

If I was to take Wolfbanes prediction for where I live then I'd be in a similar boat to you. But I'm not. I have tonnes of signal. There's enough that I could split and feed 3 TVs with a simple passive splitter and still hit 100% Quality and 80% Strength on all the main muxes. So, what does this mean for you?

I think your best plan would be to do this in two stages. The first part is putting in the aerial to see whether the predictions are correct. On the aerial choice, the highest gain aerials are massive. You're looking at anything from 6ft to 7.5ft long! See this Crossbeam XB16K. That's fine outside, but not very practical in a loft. However, if the local field strength is higher than predicted then you could get away with a shorter aerial more suitable for lofts without giving away too much gain. A Crossbeam XB10K would be a good start. That would still be really good outdoors too. The second part is seeing if you then need some additional amplification after the loft installation is done.

There are other aerial options. A Log36 is perhaps one of the most compact and it offers more gain than the standard Log aerials sold by the DIY sheds and catalogue suppliers such as B&Q, Argos, Screwfix and Toolstation. None of these places are aerial specialists, and so their stock is chosen on the basis of what makes the most profit for the retailer rather than what's the best choice for the purchaser.

All the links posted point to AerialsandTV. They're a really knowledgeable reseller with a stock selection that you won't find in the DIY stores. For the record, I have no affiliation with the company or its staff.
 
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Thanks Lucid for sll the advice. I won't pretend I understand it all but it's certainly helpful.
I'm going to try the xb10 in the loft and see how we get on.
I'm getting my sister to double check she can't mount outside just in case signal not great from loft.

She has 4 tvs she wants working so I'm thinking I'd need to get a powered amplifier rather than a passive splitter given everything you've said about weak signal area.

My other concern is the type of cable the builders have used and how well its been connected. They've installed outlets which I wouldn't normally do so hopefully they've done a decent job ( new build so doubtful)

Edit...having said all this, they only sell the loft mount kit as a set with an aerial but the xb10 isn't included, it's the log36 or yagi so is there a specific reason for this.
I can get a loft kit elsewhere if need be
 
If you are mounting it in the loft simply hang it using string initially to simply see what the signal level might be. Mind you I have seen loft installs where the aerial was just lying on top of cardboard boxes!
 
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