Fm Aerials
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Aerial Installations for FM All FM receivers benefit from a permanent FM aerial installation. If your FM radio has an aerial socket it should be connected to an external aerial to enable it to give you the best sound quality and to enable you to receive as wide a range of stations as possible. Select a good directional aerial and make sure it comes from a reliable manufacturer proud to display the company name. Check that it covers the whole of the VHF/FM Band 87.5 - 108 MHz (most do).
Aerial Positioning
Raise the receiving aerial as high as possible. Usually the signal will be stronger as the aerial is raised above the ground - the screening effect of hills, trees and buildings lessens with increasing height. The safest recommendation is to position the aerial at roof-top height at least 1 metre clear of the roof and other aerials.
The aerial is normally best mounted for horizontal polarisation, with the elements parallel to the ground. All main transmitters and most relays are mixed polarised, with equal horizontal and vertical powers. When the listener is at some distance from the transmitter, it can be beneficial to try both polarisations.
Some small relay transmitters broadcast only with vertical polarisation, and these require the aerial to be mounted with the rods vertical.
Position the aerial critically if reception is difficult. Sometimes it is beneficial to have the aerial positioned so that part of the house roof blocks out unwanted FM signals which cause interference. Shielding from road traffic interference can also be achieved in this way.
Check if there is hiss in the background of the FM station which diminishes or disappears when the radio is switched to mono. If you live in an area of low signal strength a larger aerial with a greater number of rods may be needed.
Cabling
Use good aerial cable such as the low loss coaxial type used for television reception.
Avoid cable joins if possible, but if you need to, use good quality soldered plug and socket connectors
Never twist wires together.
Never have sharp bends in the cable and never use staples.
Use cable clamps and saddles of sufficient size to avoid compressing and damaging the cable.
The FM aerial can be connected to an existing television aerial downlead, but combiner and diplexer units must be incorporated to isolate the radio and television signals from one another. Use a splitter/combiner if more than one radio is to be fed. A passive unit may be used in areas of high signal strength but in other areas a unit incorporating an amplifier may be necessary (known as a distribution amplifier. More information about radio reception can be obtained from: BBC Reception Advice Television Centre London W12 7RJ 0870 0100 123 (UK only - national rate call) http://www.bbc.co.uk/reception Ceefax page 698
Aerial Positioning
Raise the receiving aerial as high as possible. Usually the signal will be stronger as the aerial is raised above the ground - the screening effect of hills, trees and buildings lessens with increasing height. The safest recommendation is to position the aerial at roof-top height at least 1 metre clear of the roof and other aerials.
The aerial is normally best mounted for horizontal polarisation, with the elements parallel to the ground. All main transmitters and most relays are mixed polarised, with equal horizontal and vertical powers. When the listener is at some distance from the transmitter, it can be beneficial to try both polarisations.
Some small relay transmitters broadcast only with vertical polarisation, and these require the aerial to be mounted with the rods vertical.
Position the aerial critically if reception is difficult. Sometimes it is beneficial to have the aerial positioned so that part of the house roof blocks out unwanted FM signals which cause interference. Shielding from road traffic interference can also be achieved in this way.
Check if there is hiss in the background of the FM station which diminishes or disappears when the radio is switched to mono. If you live in an area of low signal strength a larger aerial with a greater number of rods may be needed.
Cabling
Use good aerial cable such as the low loss coaxial type used for television reception.
Avoid cable joins if possible, but if you need to, use good quality soldered plug and socket connectors
Never twist wires together.
Never have sharp bends in the cable and never use staples.
Use cable clamps and saddles of sufficient size to avoid compressing and damaging the cable.
The FM aerial can be connected to an existing television aerial downlead, but combiner and diplexer units must be incorporated to isolate the radio and television signals from one another. Use a splitter/combiner if more than one radio is to be fed. A passive unit may be used in areas of high signal strength but in other areas a unit incorporating an amplifier may be necessary (known as a distribution amplifier. More information about radio reception can be obtained from: BBC Reception Advice Television Centre London W12 7RJ 0870 0100 123 (UK only - national rate call) http://www.bbc.co.uk/reception Ceefax page 698
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