I am going to replace my tv aerial as its really old and the picture keeps breaking up. so started looking in the c.p.c. catalogue and well there is a lot to choose from the price seems to go up with the number of elements is that relevent? some advice would be welcome thanks
new tv aerial
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TV aerials come with many designed the most used was designed by a radio ham called Yagi I think for Japan. But as we compare the different designs the gain and band width do not always compare with number of elements. A HB9CV with two driven elements can preform better than a 4 element Yagi for example.
So counting the elements is not the whole story. There are three basic things we look for.
1) Gain
2) Band width
3) Polarisation
Although there may be the odd time where we want to receive vertical and horizontal on the same aerial that is rare so we will forget polarisation which leaves gain and band width.
In general to get more band width we make the aerial longer and to get more gain we add elements. If you over do it the aerial becomes heavy and more likely to be effected with electrical storms so step one is to work out what band width is required.
Years ago we all used banded aerials normally with a coloured bung at the end to show which band it was set for. As digital arrived the TV broad cast could no longer be confined to one band for each area so we started using larger broad band aerials often refereed to as digital aerials although really the wrong name. However as analogue was switched off many areas returned to being able to use a banded aerial and if yours is one then that is far better as they are smaller and cheaper than the wide band with same gain.
The gain is rated in db a di-pole is 1 db and as we add elements we can make the aerial directional (vertical di-pole is omni-directional) and also increase the gain. The gain required will vary as to how close one is to transmitter and how many TV's you want to feed without using an active splitter. By using a pre-amp one can reduce the db gain required but in general better to have too much than too little.
TV's can get too much signal and one could need to use an attenuator if that was the case but that again would be wasting money and attracting problems with electric storms.
Aerial installers will know how much gain is required but for the DIY man one has to make a guess. Looking at other houses can help but if DIY is the norm then likely other houses have over sized aerials anyway. Some people seem to think the bigger the better.
There are I think some internet charts which in general will show at your location the gain required.
So counting the elements is not the whole story. There are three basic things we look for.
1) Gain
2) Band width
3) Polarisation
Although there may be the odd time where we want to receive vertical and horizontal on the same aerial that is rare so we will forget polarisation which leaves gain and band width.
In general to get more band width we make the aerial longer and to get more gain we add elements. If you over do it the aerial becomes heavy and more likely to be effected with electrical storms so step one is to work out what band width is required.
Years ago we all used banded aerials normally with a coloured bung at the end to show which band it was set for. As digital arrived the TV broad cast could no longer be confined to one band for each area so we started using larger broad band aerials often refereed to as digital aerials although really the wrong name. However as analogue was switched off many areas returned to being able to use a banded aerial and if yours is one then that is far better as they are smaller and cheaper than the wide band with same gain.
The gain is rated in db a di-pole is 1 db and as we add elements we can make the aerial directional (vertical di-pole is omni-directional) and also increase the gain. The gain required will vary as to how close one is to transmitter and how many TV's you want to feed without using an active splitter. By using a pre-amp one can reduce the db gain required but in general better to have too much than too little.
TV's can get too much signal and one could need to use an attenuator if that was the case but that again would be wasting money and attracting problems with electric storms.
Aerial installers will know how much gain is required but for the DIY man one has to make a guess. Looking at other houses can help but if DIY is the norm then likely other houses have over sized aerials anyway. Some people seem to think the bigger the better.
There are I think some internet charts which in general will show at your location the gain required.
my aerial at the moment is a basic design and now and then will not tune to certain channels and playing with the remote control I have found that the signal strenth is 78% so I thought a new aerial plus cable would sort it out as the aerial we have now is very old thanks for the information.
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See SatCure's advice: http://www.satcure.co.uk/tech/best_aerial.htm
and ATV's: http://www.aerialsandtv.com/atvschoiceofaerials.html
and ATV's: http://www.aerialsandtv.com/atvschoiceofaerials.html
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