TV Signal Guide-Outdoor Antennas



Untitled Document



OUTDOOR ANTENNAS:



Outdoor antennas are always better than indoor antennas. A good outdoor antenna,
properly installed, is your best bet for signal reception. There are many different
kinds available in a wide range of prices. Keep in mind that bigger is not always
better.


Antenna height is the single most important issue for good reception. The higher
the antenna above ground the better. This will give you better clearance above
other buildings, trees and ground based interference. An antenna should also
be at least six feet above the roofline to reduce unwanted bounce and reflection
of signals or other types of interference. Generally speaking, every ten feet
of additional height will nearly double the relative signal strength of a station.
A "cheap" antenna 30’ above ground can perform as well as the
"most expensive" antenna only 10’ above the ground.


The next most important aspect of an antenna is "gain". Gain is the
measure of an antenna’s sensitivity, or its ability to pick up signals.
The farther you live from the station tower, the more gain your antenna should
have. Gain is also important in areas with "ghosting" or "multi-path".
Gain adds directionality to the antenna, which enables it to pick-up the strongest
signal and reflect, or reject, the bouncing signals from the side or back of
the antenna. While some manufacturers do list the gain on the product, most
use a mileage rating to estimate the antenna’s performance.


Gain will vary from channel to channel. For example, an antenna’s advertised
top gain rating may be at channel 8 or 10, but the gain may be much less at
channel 30. Purchase an antenna suited for your weakest signal. This will assure
optimum performance of your system.


The following chart is for TV antennas manufactured by Winegard,

one of the nation's leading antenna manufacturers.


MILEAGE CHART

This chart will help you select the Winegard off-air antenna best for your viewing
area. These ratings are based on optimum conditions on unobstructed terrain.
Type of terrain and weather conditions will influence your selections of an
antenna.


MILEAGE REFERENCE CHART FOR OFF-AIR ANTENNAS





































































Area Designation


For VHF For UHF Boom Length # of Elements
Deepest Fringe 100+ Miles 60+ Miles 170" + 70+
Deep Fringe 100 Miles 60 Miles 160" - 170" 48-60
Fringe 80 Miles 45 Miles 135" - 150" 40-45
Near Fringe 60 Miles 35 Miles 110" - 130" 35-40
Far Suburban 50 Miles 35 Miles 80" - 100" 30-35
Suburban 45 Miles 30 Miles 60" - 75" 20-30
Far Metropolitan 30 Miles 25 Miles 40" - 60" 15-20
Metropolitan 25 Miles 15 Miles 33" - 40" 10-15


As the chart clearly shows, most combination antennas are rated high for VHF
reception, but their performance in the UHF band, in our case channel 30, is
almost always 40-50% lower. The average antenna sold today has a VHF mileage
rating of 60 miles, but its performance for UHF signals is only 35 miles. If
you add any trees or buildings in the path, that performance will be reduced
substantially.


Since most antennas are designed for better VHF reception, often the best solution
to UHF reception problems is the addition of a separate UHF only antenna. This
way you can maximize the gain in the frequency range you need, and also be free
to point the UHF antenna exactly where it needs to be. All outdoor antennas
are directional to some degree. If the stations you are trying to receive are
in different locations, separate fixed position antennas require much less maintenance
and realignment that the use of a rotating system. This installation also allows
for the amplification of just the UHF antenna if necessary. Just be sure that
if multiple antennas are mounted on the same mast, they should be spaced a minimum
of five feet apart to avoid interfering with each other.


THE PROPER ANTENNA FOR THE JOB


Make sure you have the right type of antenna for your needs. Antennas vary
from VHF only, to combination VHF/UHF, to UHF only. Make sure you know what
you have. While a VHF only antenna may get lucky and pick up a nearby UHF channel
or two, it will not pick up distant or high band channels.




Remember, bigger is not always better. While a giant combination antenna will
work if all stations are close and they are all in a straight line from your
home, that rarely is the case. A separate antenna, with the correct height,
gain and orientation will provide the best picture possible.


ATTIC INSTALLATIONS


Many people have installed TV antennas in an attic to avoid climbing on the
roof or paying an installer. While this may be a safer installation, it is generally
far more costly, and it defeats the intended purpose. Installing an outdoor
antenna in the attic reduces the effectiveness of the antenna by over 50%. Add
to that any foil type insulation, metal heating ducts or glass windows, and
you have eliminated most of the gain built into the antenna. While the added
height may perform better than a typical indoor set-top antenna, you will lose
much of the value of the normal antenna. The cramped space in an attic usually
hinders the correct orientation of the antenna due to the shape or size of the
antenna and the various obstructions an attic usually presents. Attic installations
are a problem if not all TV stations are in the same direction.


If you must install an antenna in an attic, plan ahead. Find the exact direction
of the TV tower you want to reach, and measure the amount of room the attic
then allows. Ask your antenna retailer for the highest gain antenna made with
a boom length that will fit in that measurement. Mount the antenna on a vertical
mast above the joists. Laying the antenna across the joists will allow the antenna
to lean at an angle and may create unwanted ghosting. Your retailer will probably
suggest adding an amplifier of some type to help overcome the signal loss from
the attic, but keep in mind, an amplifier amplifies the signal and any noise
or interference you may get.


Q. My antenna is in the attic and it worked OK for the old location, what can
I do?


In reality, many people do not want to make major changes to their existing
systems. However In this case, the best solution is to add an antenna pointed
in the correct direction. The two antennas can then be wired to a signal combiner
so you still have only one wire going down to your TV. This also allows you
to put an amplifier on just the new antenna line, to help make up for the signal
lost by the indoor installation. The two antennas should be separated as much
as possible to avoid interfering with each other. Attic installations should
always use the highest gain antenna available and practical.






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