To many, TV antennas are simply useless antique relics from
the past.However, most people don’t
know that a classic TV antenna can bring your TV into the future of high
definition viewing.If you’ve been
watching American broadcasting stations recently, you’ve probably seen public
service announcements about the big changeover to digital television. On
February 17, 2009, American over-the-air television broadcasting as we’ve known
it over the past 75 years will change forever.The Canadian digital changeover will occur after August 31st,
2011.
Once the US digital transition takes place, Canadians with
analog televisions will no longer be able to receive over-the-air (OTA) digital
signals from US broadcasters without a digital-to-analog converter box, or a
television with a built-in digital tuner.
Canadians who already have
televisions with a digital tuner or who subscribe to satellite or digital cable
service should see no change.
Here are some videos that help explain the digital conversion beginning in the
United States:
The change from analog to digital TV broadcasting brings
with it much renewed interest and excitement. Previous issues with ‘snow’ and
‘ghosting’ images that were associated with analog over-the-air transmissions
will be a thing of the past. In the new digital era, there will be a high
quality picture or no picture at all (and nothing in-between). The truest
benefit will come from primetime broadcasting and major sporting events.
Best of all, over-the-air signals are free to receive.
Aside from the cost of equipment to receive the signals, there are no ongoing
subscription or access fees.
Typical Cable TV and Satellite providers offer hundreds of
channels to their subscribers over their distribution medium. However, in order
to send all those stations to your home, they use heavy data compression that
degrades picture quality.Digital
artifacts, soft images, distortion, pixilation, and poor colour reproduction are
all side effects of compression.
Over-the-air antennas allow you to receive uncompressed
high-definition signals direct from broadcasters in both Canada and the US;
therefore, giving you the best possible picture on your HDTV.
Over-the-air transmissions are “line-of-sight”, and
therefore the key to success for reliable reception is a clear path to broadcast
transmitters (such as the CN Tower). Remember, the earth is round, and the
curvature of the earth will impact reception from transmitters beyond 70 miles
(112 Km). There are many website tools that you can use to pinpoint the location
direction and the distance of broadcast towers.
http://www.tvfool.com - This is a great website tool that can help answer
questions like:
Which broadcaster are transmitting locally?
How far are the transmitters from me?
Which direction should I point my antenna?
How strong are the signals in my area?
What analog and digital channels are available?
For Canadian users, just enter your address in the
"Address" field, enter your City, Province in the "City" field, and enter your
Postal Code in the "Zip" Field. Just ignore the "State" drop-down menu.
Tip: Small adjustments to your antenna can make a
big difference in the number of digital channels you can receive. If you have an
indoor antenna, try elevating it and moving it closer to an exterior wall of
your home. After adjusting your antenna, perform another channel scan to see if
you reception has improved.
Tip: Try using a simple compass to help point you
in the right direction. By using the information gathered from the websites
above, you can use a compass to quickly find the direction to point your
antenna.
Due to the proximity of most major metropolitan Canadian
cities are in close proximity to major US cities, many Canadians should be able
to receive broadcasts for major network channels such as ABC, NBC, CBC, CBS,
etc. Most broadcasters locate their towers in generally the same area; therefore
it’s likely you can point your antenna in one direction to receive multiple
stations.
http://www.remotecentral.com - This is an excellent website that provides
valuable information on HDTV products. Their OTA channel listing for the Greater
Toronto Area is an excellent resource for those looking to know what is out
there.
When an analog off-air broadcast signal is weak or receives
interference, static, snow, and distortion will often result on the screen.
Digital off-air braodcasts will provide excellent clear pictures; however, if
the signal falls below a certain minimum strength, the picture will likely just
disappear. This "cliff effect" means that if you watch off-air analog TV
stations that have static or distortion, you may have to adjust or upgrade your
antenna system.
Tip: try to keep the length of wire between your
antenna and digital tuner as short as possible for the best reception.
TV antennas come in various sizes and shapes.
There are many bands and hundreds of TV
antenna models available. However, choosing the right one is relatively easy if
you are aware of the few basic reception and TV antenna characteristics. TV
signals received by antennas are either VHF (Very High Frequency), or UHF (Ultra
High Frequency). Most broadcasting stations are using the UHF frequencies.
First, “good reception”, or production of a snow-free
colour TV picture, requires a signal level of about 100 microvolt’s. To deliver
this signal level to the receiver, the antenna requires a certain antenna gain.
The amount of gain required is dependent on the distance between the station’s
transmitting antenna and the receiving antenna. The required type of antenna
therefore depends on the channels to be received and the distance and direction
of the customers home from the transmitting antennas. These facts are readily
available for any area, but be sure your information is accurate and complete.
Call a local TV station if you have questions. Most television stations are
willing to help TV antenna installers because they also benefit from the
improved reception to the stations viewers.
Not one single antenna will deliver excellent TV reception
in every location.The most
important point to remember when selecting an antenna is its gain, sensitivity
classification, directivity, and front-to-back ratio.
VHF/FM Antennas1
Most VHF (Very High Frequency) antennas are engineered to
receive TV Channels 2 through 13. They also will receive the FM radio band,
which is located between TV channels 6 and 7. FM ONLY antennas are also
available. Channels 2 through 6 are known as the low band. Channels 7 through 13
are referred to as the high band. Some VHF antennas are designed to receive only
one band, either the low or the high band. Antennas designed to receive both the
low band and the high band is called VHF/FM broadband antennas.
UHF Antennas1
UHF (Ultra High Frequency) antennas are designed to receive
TV channels 14 through 69, the UHF TV band. UHF TV antennas come in a wider
variety of shapes and sizes than VHF/FM antennas. The variety of UHF designs is
possible because they do not require the long elements the VHF/FM antennas do.
WARNING: Prevent
Electric Shock1
WARNING! Installation or removal of antennas near power
lines is dangerous. For safe installation, read and carefully follow the
instructions included with every antenna. Never let any part of the antenna,
mast, or guying assembly touch any power line. If a metal part does touch a
line, it will complete an electrical path through the antenna to you, and you
could be killed or seriously injured. We strongly recommend that you stay a
distance away from power lines of a minimum of twice the total length of the
antenna and mast.
Gain1
The gain of an antenna indicates the relative strength of a
signal it can deliver to a receiver. Most manufacturers list gain in their
antennas in decibels (dB). The higher the antenna gain, the stronger the signal
at the antenna output terminals. In most cases the larger the antenna, the
higher the gain.
If you are in doubt about the amount of gain required,
select an antenna that is slightly larger than you think is actually needed. The
performance of all components deteriorates slightly during the years as they are
exposed to rain, sun, wind and corrosion. Consequently, to ensure quality
reception for a longer period, choose and antenna with a little more gain than
is necessary. (NOTE: Excessive gain may cause overloading. Therefore choosing
the antenna with the highest gain might create more reception problems than it
cures.)
Sensitivity classifications are used to indicate the type
of reception for which the antenna is designed. Certain ranges of gain are best
suited for certain types of areas. The appropriate range of gain for a specific
area is what a manufacturer is indicating when labeling an antenna, i.e., Outer
Suburban or Near Fringe.
Typical Sensitivity Classifications Table:
Area Designation
VHF (km / mi)
UHF (km / mi)
Deepest Fringe
160+ /100+
97+ / 60+
Deep Fringe
160 /100
97 / 60
Fringe
129 / 80
72 / 45
Fringe
129 / 80
72 / 45
Near Fringe
97 / 60
64 / 40
Far Suburban
80 / 50
56 / 35
Suburban
72 / 45
48 / 30
Far Metropolitan
48 / 30
40 / 25
Metropolitan
40 / 25
24 / 15
This table indicates in miles and kilometers, how close an
antenna must be to the transmitter to produce the best signal level. The
classifications are somewhat general because reception conditions at various
sites within a particular type of area may be different.
Directivity1
Directivity is the ability of an antenna to intercept
signals from only one direction and reject those from other directions.
Directivity indicates the antennas ability to intercept signals at its front and
reject signals coming from the rear and sides.
The front-to-back ratio of an antenna can be helpful when
attempting to determine its directivity. Front-to-back ratio is expressed in
decibels (dB). This ratio indicates an antenna’s ability to reject signals
coming from the rear. For example an antenna with a front-to-back ratio of 25 dB
will receive about 18 times more signal from the front than from the back.
Beam width is related to an antenna’s overall gain and
indicates how wide or narrow the reception area of the antenna is. For example,
if two antennas have the same front-to-back ratio, the one with the highest
overall gain will have the narrowest beam width and consequently, will be the
most directive.
An antenna with a relatively narrow beam width generally is
best suited for areas where interference from both sides is a problem. An
antenna with a broad beam width is best suited for areas where a broad beam is
needed to capture the signals from widely separated stations, and where
interference is minimal. Beam width information, if included by the manufacturer
is usually displayed by polar plots.
Simple indoor antennas provide minimal performance that may not be suitable for
your location. Indoor antennas are easy to install and setup and generally work
very well when you are near broadcasting towers. However, they have a very
limited reception range, and they have to contend with many obstructions that
affect signal strength. Generally, an outdoor antenna will get better
reception than an indoor antenna. However, the performance of an outdoor antenna
can degrade over time due to exposure to the weather.
Buy an outdoor antenna that best suits your needs. Make sure you get a complete
mounting kit as well as any other accessories you might need to mount your
antenna to your roof, wall, chimney, or attic.
Take safety precautions when climbing a ladder and/or getting onto the roof.
Make sure your ladder extends well past the roof line and wear shoes that will
give your feed a good grip on an angled surface. Wear protective
clothing/equipment for knees and elbows. Remember on a hot summer day, the roof
can get quite hot. Take extra care when placing your steps to anticipate
stepping on a loose shingle. And stay clear of power lines.
Choose the mounting location for your outdoor antenna. This is usually in a location that is as high as possible.
Additional height may help you pull in signals you were previously unable
to pick up. Broadcast towers are land based, so you will need to be sure that your location allows for adjustments. Make sure to avoid interference from other buildings and trees.
Connect as short-as-possible standard RG6 coax cable between your antenna and
HDTV (long cable runs will decrease signal strength and may require a pre-amp.
If at all possible, do not use any splitter/junctions or at least keep them to a
minimum. If you need to use splitters, strongly consider a distribution
amplifier to keep the gain up.
Many people prefer to keep an antenna mounted in an attic for protection from the weather and to keep the outside of their homes uncluttered. The drawback is that building materials can greatly affect performance and may cut as much as 50 percent of the signal. For example, if you have any kind of aluminum or sheet metal in or under your roof or siding (including foil-backed insulation), then many of the signals would be reflected and blocked from your antenna. An antenna pre-amplifier may help in some of these situations. To mount an antenna in an attic, you can attach a roof-type mast pole to a cross brace that
is attached to your rafters. Attach the antenna to the bottom of the mast pole, but make sure the antenna still remains in its normal right-side-up position. Alternately, you can suspend the antenna from the rafters with nylon rope or guy wires. If using guy wires, make sure they do not contact the antenna elements or they will cause a short. Also, make sure the antenna does not touch the floor.
Antenna Grounding
Every TV antenna installation be grounded. Some areas also have local antenna grounding codes to abide by.
Please check with your local municipalities for details.
For exterior antennas (especially rooftop), the antenna mast and coax both need to be properly grounded to prevent electrical surges from lightning strikes.
Sensuz Media inc recommends hiring a professional when installing and grounding
rooftop antenna. Sensuz Media is not responsible or any damages caused by
improperly grounded equipment.
Run your coax from your antennas coax out to a grounding block as directly as possible without any sharp bends. Leave a drip-loop in your coax cable near the grounding block to prevent moisture from entering the connections. The coax from the house will then attach to this grounding block.
It is also a good idea to have a surge suppressor with coax input and output inside your home. Grounding the coax will ground the active/driven element, but that is electrically isolated from the rest of the antenna. To ground the mast, you can run a separate ground wire from the grounding block to the mast and attach to one of the mounting bolts. Alternately, you can use a short piece of grounding wire and attach it to the mast via a grounding strap or grounding clamp. Then run the wire to the outer shell of the coax connector and attach with a grounding strap.
If you do not already have a grounding block, get one and place it outside your home, near where the coax enters your house. Connect the grounding block to your house ground, or run a ground wire from the block to a ground rod, driven into the ground, or to a cold-water pipe.
Factors that may Cause Poor Signal Performance
The signal pickup elements are too small for appropriate coverage. An antenna with larger antenna conductors would also have a wider
frequency bandwidth.
The antenna is inside, try moving it outside or adding a pre-amplifier.
The antenna amplifier is of low-grade quality... upgrade to a high-quality, high-gain, low-noise pre-amp.
Your using a Multi-directional antenna which is not as powerful as a Unidirectional antenna.
The transmitting tower is too far away or transmitting at a lower power output than other transmitters.
There is something causing blockage or interference in your local environment (i.e. airport, building materials, loose cable, mountain, etc.)
Your coax cable feed line is running next to an electrical line that may be generating noise in the cable. Try not to run your coax cable parallel to electrical lines, and if you must cross an electrical line, do so at a 90-degree angle.
HDTV
i-Buddy
