Difference between revisions of "VHF aerial"
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==UHF TV aerial== | ==UHF TV aerial== | ||
| − | UHF TV | + | UHF [[TV aerial]]s don't make good VHF FM aerials, but they're often much better than internal VHF antennas, telescopic rods, or the popular rabbit's ears, and most people already have one fitted. If you've decided not to spend money on a VHF aerial, in many cases you can get a real improvement in FM reception by using a diplexer at the radio to split off any VHF received by the TV aerial and pass it to the radio. |
Performance varies from one TV aerial type to another, and a random UHF aerial may give anything from no signal to a good signal. | Performance varies from one TV aerial type to another, and a random UHF aerial may give anything from no signal to a good signal. | ||
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A small number of TV aerials are designed to give VHF reception as well as UHF. These aerials are easily spotted, they look like standard TV aerials, but have one or 2 elements that are much longer than the others. | A small number of TV aerials are designed to give VHF reception as well as UHF. These aerials are easily spotted, they look like standard TV aerials, but have one or 2 elements that are much longer than the others. | ||
| − | These give significantly better VHF reception than UHF only TV aerials, though performance is inferior to a dedicated VHF aerial. The advantage of these is you only need one aerial, one downlead and no combiner. | + | These give significantly better VHF reception than UHF only TV aerials, though performance is inferior to a dedicated VHF aerial. The advantage of these is you only need one aerial, one [[Cable for TV aerials|downlead]] and no combiner. |
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==Halo== | ==Halo== | ||
| − | A ring shaped omnidirectional antenna | + | A ring shaped omnidirectional antenna, these are very common. |
Less gain than directional types, but can still often produce a good signal. | Less gain than directional types, but can still often produce a good signal. | ||
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==Rabbits ears== | ==Rabbits ears== | ||
| − | Rabbits ears are a T shaped piece of twin wire. The ears are moved about to sometimes get passable reception, and typically fixed to the wall with blu-tak. | + | Rabbits ears are a T shaped piece of [[flex|twin wire]]. The ears are moved about to sometimes get passable reception, and typically fixed to the wall with blu-tak. |
| − | Although very inferior to rooftop aerials, they're | + | Although very inferior to rooftop aerials, they're an improvement on a random piece of [[flex|wire]]. |
==Telescopic rod & Wire== | ==Telescopic rod & Wire== | ||
| − | Telescopic metal rods and lengths of wire are the lowest performance VHF aerials. However they're often built into radios as they cost so little. | + | Telescopic metal rods and lengths of [[flex|wire]] are the lowest performance VHF aerials. However they're often built into radios as they cost so little. |
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| + | Sometimes the reception of a wire aerial can be improved by snaking it round the [[flex|mains lead]] for capacitive coupling. | ||
Revision as of 00:43, 6 March 2009
This article is a work in progress. Content should not be relied on yet.
FM radios can give much better reception and often more channels if connected to an aerial.
UK FM radio is transmitted on VHF frequencies, so the terms FM and VHF are often used interchangeably.
VHF Aerial types
3 element FM aerial
These are the best performers for VHF reception. They do however need to be pointed toward the main transmitter, random orientation gives middling results.
UHF TV aerial
UHF TV aerials don't make good VHF FM aerials, but they're often much better than internal VHF antennas, telescopic rods, or the popular rabbit's ears, and most people already have one fitted. If you've decided not to spend money on a VHF aerial, in many cases you can get a real improvement in FM reception by using a diplexer at the radio to split off any VHF received by the TV aerial and pass it to the radio.
Performance varies from one TV aerial type to another, and a random UHF aerial may give anything from no signal to a good signal.
VHF / UHF aerial
A small number of TV aerials are designed to give VHF reception as well as UHF. These aerials are easily spotted, they look like standard TV aerials, but have one or 2 elements that are much longer than the others.
These give significantly better VHF reception than UHF only TV aerials, though performance is inferior to a dedicated VHF aerial. The advantage of these is you only need one aerial, one downlead and no combiner.
Halfwave dipole
Very good
Folded dipole
Good.
Halo
A ring shaped omnidirectional antenna, these are very common.
Less gain than directional types, but can still often produce a good signal.
Rabbits ears
Rabbits ears are a T shaped piece of twin wire. The ears are moved about to sometimes get passable reception, and typically fixed to the wall with blu-tak.
Although very inferior to rooftop aerials, they're an improvement on a random piece of wire.
Telescopic rod & Wire
Telescopic metal rods and lengths of wire are the lowest performance VHF aerials. However they're often built into radios as they cost so little.
Sometimes the reception of a wire aerial can be improved by snaking it round the mains lead for capacitive coupling.
material for the TV aerial article
A metal diplexer only costs 2 or 3 pounds.
Avoid £1 unscreened plastic diplexers, these let interference into the aerial system, affecting digital reception.
Avoid using a splitter instead of a diplexer, as these cause an extra 3-4dB loss, often degrading reception.