My house has the TV aerial mounted in the loft, (this was done by the previous owner) it looks like the one at the bottom of page 326 in the Screw F catalogue and is described as a professional 16.5db gain for use in fringe reception areas. We don't live in a 'fringe' area - judging by the looks of the aerials on other people's chimneys.
On analogue TV Channel 4 is a bit snowy and the rest are OK. On freeview I can only get 3 or 4 channels, and all the rest are either total crap or nothing at all.
Here's my questions: How much of an obstacle to the signal is the gable end of the house? (breeze block and brick outer) Would moving the aerial outside make a difference to reception ? And/or would fitting a signal booster to the coax cable solve the problem?
I'm not sure really why the aerial was mounted in the loft in the first instance - maybe for cosmetic reasons...
Every edition of Screwfix catalogue is different and unless you buy from them on a regular basis others may not have the most up to date copy. The cable ties on page 326 are unsuitable for use as an aerial :)
Unless you actually know it is a Screwfix aerial then be aware that you can get either a group aerial for a limited range of frequencies or a wideband aerial to accept all frequencies. A group aerial will give a better performance than a wideband of the same size.
Screwfix tend to only sell wideband aerials..
Which channels are totally missing?
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you have grouped aerial then it may be unsuitable for digital. In many areas the same aerial can be used for both analogue and digital but in other areas a change in aerial is required for digital.
Do you know from which transmitter you are obtaining your signal? If not put your postcode into
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found your transmitter go to
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find in one of the pages that are listed by region the same transmitter.
In one of the tables the aerial group for Analogue (A) is listed and next to it the aerial group for analogue plus digital (A+D) is listed. If they are both the same then your existing aerial is probably OK but if they are different a different aerial may be required.
The missing digital channels and the name of the transmitter may give clues to which aerial you have. Post back with the transmitter details and someone should be able to advise.
In general, an aerial mounted on the roof is going to be a lot better than one mounted in a loft.
An aerial booster may help if the signals are marginal but of no use what so ever if the aerial is incorrect for all the digital MUXs.
If you are thinking of DIY then also consider installing a decent fully screened down-lead such as CT100 (approved satellite quality cable)
I looked out some figures from an installation I had done a while ago. In the low end of band V (about 650MHz), my installer measured 17dB difference with the same antenna installed in the loft vs. it being about 2m vertically above, outside. He also compared the readings for the same height outside as the internal fixing, and the difference between the two exterior readings was about 1.5dB. The equivalent comparisons at the low end of Band IV (500MHz) were about 15dB inside to out and at the top of Band V (830MHz) was 21dB.
While only three datapoints, this does suggest that the attenuation is rather worse than linear with frequency.
I'm told that some building materials have quite a metallic content and I am sure that this wouldn't help either.
This was all before DTTV, so I don't know what the results for that would have been like, but I do remember the analyser showing cruddy results and there was a lot of close distance multipath evident on an analogue picture.
I'm sure it won't be a Screwfix aerial, because Screwfix didn't exist when this one was installed! I just wanted to use it as an example of an aerial with three forward facing 'prongs' (sorry for the untechnical description!)
sense judging from the direction that the aerial (and the neighbour's) is pointing.
Checked this, it's aerial group c/d for both.
This one is difficult. Multiplex 1 for sure, but BBC 3 is weak. Multiplex 3 is mostly weak or nothing. A and B is mostly nothing. C is good. D is mostly nothing. I've noticed that dry high pressure days in winter seem to allow a better picture than wet summer ones.
Thanks for your help. I'm thinking that I need to mount the aerial outside and use some decent cable. Cable won't be easy because most of it is buried beneath the plaster :-(
I think it may be easier to get a professional in to sort it out, I'm struggling to understand it all fully!
Thats really quite close , assuming there are no big obstructions in the way like hills I would have thought there should be plenty of signal for all analogue channels.
Have you checked the connections and coax ? A quick check that the loft aerial is giving a better signal than a set-top aerial might be worthwhile.
It it was diy job by previous owner and the aerial isnt wide-band did he buy the right one ?
It may be easier to run a new cable outside of the house.
If the previous owner has run cable to all rooms did he also install a distribution amplifier in the loft? It is not unknown for distribution amplifiers to fail.
No, there's just a little 'Y' two into one affair in the loft. I've also tried the telly up in the loft via an extension cord and connected direct to the aerial to eliminate stuff.
I'm now 99% certain that the problem lies with the aerial location, so I'll get it moved or replaced to outside, probably by professionals - there's too much PFM with this signal stuff for my liking!
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