Since 1982 when first licensed I have played with aerials. From the yagi to HB9CV even a slim jim made from 300 ohm ribbon cable stuck to my window in Hong Kong.
There is no substitute to metal in the air. It is after all where the aerial gets its name. Having said that with TV the band is quite big.
Channel 21 to 68 spans from 512 to 800 Mhz and to be honest nothing but the most basic aerial can encompass such a range.
Historically the TV aerials were split into bands which were shown by coloured plastic ends fitted to the aerial.
So red covers 21 - 37 and yellow 35 - 53 and so on with black being wide band 21 - 68 see
here for all colours.
Once you have selected the colour for your area you then need polarisation. Most main transmitters are horizontal and most repeaters are vertical.
With the original 4 channels the country wide system allowed each area to have a band so for example the North West of England from Winter Hill was Green channel 48 to 68. However with the introduction first of channel 5 and then freeview the channel availability was somewhat stretched and the multi-plexed transmissions had to be slotted into any available space. This meant only a wide band aerial (Black) would receive all stations.
However the wide band aerial is much bigger than the traditional narrow band and has more wind resistance and therefore more likely to be damaged plus of course also more likely to be effected by electrical storms.
With the demise of analogue again the regions can reduce their band width and again we can use banded aerials so reducing likely damage by wind or electrical storms.
Plus the repeater network has been rationalised which has resulted in aerials changing in both direction and polarisation.
Huge posters tell us all about the big switch off but information as to where to re-direct the aerial has not been so forthcoming.
Since this all varies area to area to give advice away from ones own area is hard.
However I would advise anyone who can receive on a loft aerial to do just that and avoid the problems of wind and electrical storms. If they do need to go outside I would wait until after change over and check on new frequencies and use the narrowest band that will receive all those frequencies and so reduce the chance of wind or electrical storm damage.
If outside then de-coupling capacitors or a splitter/booster will reduce the chance of electrical storms damaging the TV set. The same applies for DVD players or sky boxes they all reduce the likely hood of storm damage.
A direct hit will fry the lot but most damage is caused by near misses not direct hits. Aerials should not be grounded as that is likely to encourage lighting to hit your aerial. They should not be placed on sharp corners like gable ends or on conducting surfaces like soot lined chimneys.
OK some times you have no option but use active chimneys as last resort. Of course non used chimneys are not a problem but avoid those with metal liners.
At the end of the day each house is different and I know one guy who found the local CB users aerial reflected TV signals A1 and he aimed his aerial at the CB aerial and there will always be the odd case which does not seem to follow what seems the best option.
As a radio ham we get stories of bouncing off air craft and all sorts of odd reception aides. So at end of the day just try it and see. Could be signal is bounced off local hill side or church spire.
Best aerial is one that works. If you talk to hams they all have their ideas of which is best. Same with CB crowd and they will tell you how this silver pole or whatever was really good. Not different with TV aerials high gain
are likely to receive better because the band is narrow but then wind is more likely to effect signal. But good aerials start at
£6 and go to £50 and in spite of all adverts there is no difference in analogue and digital as to aerial design only the band width varies.
