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Television Antenna - A television antenna is an omnidirectional antenna tuned to the broadcast frequencies assigned to television...
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Television Antennas. Television antennas are directional. They should be pointed at the transmitter
of the station you are trying to receive...
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Television Antennas
A
television antenna is basically a low tech item. It has a series of
elements cut to specific lengths that are related to the frequency
of the signal it is designed to receive. Each element is a pair of
metal (usually aluminum) rods sticking out from the boom.
The real
difference between one brand and another, assuming similar gain and
front to back ratio, will be how well anodized the metal is and
quality of construction. As the metal oxidizes and the rivets rust
the active elements lose contact and the performance suffers.
Antennas do 'wear out' with age if they are mounted outdoors.
Indoors they will last a lot longer.
Antennas are available for VHF, UHF, or VHF/UHF. If you don't need to
receive UHF channels (the ones above 13) off air then don't waste
money on a VHF/UHF combo. The FM radio band falls between channels 6
and 7 on the VHF band so a VHF antenna will usually work for FM as
well.
There are also 'channel cut' antennas. These are antennas specifically
designed to receive one channel. They are sometimes used by cable
companies to pick up local stations. A large electronics supply
house should be able to get them for you. The only use for one of
these in a home set up is in the case of a single station located in
a different direction from all the others that is difficult to pick
up. You might use a two antenna set up (see below) in that case.
Directional FM antennas are a variation of a channel cut antenna
designed to pick up the FM band.
Television antennas are directional. They should be pointed at the
transmitter of the station you are trying to receive. That is the
purpose of having a rotator. In case you don't know the tips of the
elements need to be angled toward the transmitter. Think of the
elements as "V"s with the twin top of the V aiming towards the
source.
Antennas have a specification called 'gain'. This is a measure of how
well the antenna will 'pull in' a signal at a specific frequency.
There is another specification called front-to-back-ratio. That is
how much better the antenna receives a signal coming from the
direction the antenna is pointed compared to a signal coming from
the opposite direction. Front to back ratio is what makes an antenna
directional. Many antennas do not have these specifications on the
box or in the literature. If you see these specifications just
remember that generally the larger the number the better, but since
these measurements are affected by frequency you may not be able to
compare between two different manufacturers numbers. Generally the
bigger the antenna and the more elements the higher the gain and
front to back ratio. Keep in mind though that a combination
VHF/UHF/FM antenna will have more elements than a UHF only or VHF
only antenna of the same gain.
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