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Old 2009-01-25, 08:15 PM   #20
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Default How Do I Put Up An Outdoor Antenna?

What kind of mount should I use?
Some people will find that an outdoor antenna can simply be mounted onto an outdoor wall with a bracket. Condo or apartment dwellers might put their antenna on a pole weighted in a large flower planter, or clamp a pole to their deck railing. Home owners might use a tall metal pole sunk several feet into the ground. Others will need to have their antenna as high as possible to receive the desired stations so will use a roof-top antenna using a tripod or chimney-mount. For all your antenna mount needs, see the OTA Mounts, Towers, Rigging Hardware thread.
How High Should My Antenna Be?
In layman's terms, raising the antenna shows real benefits to a point, at which the more time, money, and labour it takes to raise the antenna past that point, the lesser the benefit per dollar/hour/back spasm is achieved (the law of diminishing returns). For this reason I only recommend tall towers to people known to be in deepest fringe areas. For some rare occasions the local conditions of other folks might dictate a tower even if they are in a closer range. For the vast, vast majority of OTA users the point of diminishing returns will never be reached because reception will have already been found to be satisfactory well below that point. Having said that, in some unusual situations reception can be improved by lowering the antenna due to local issues. Deciding on whether to use a tower should be done after reading through the Reception Results thread for your area to understand local reception issues that might require one.
What about using a tower?
A few OTA users will want to opt for either a guy-wired tower or a free-standing, self supported tower, while rural dwellers in deep to deepest fringe areas will likely need to use a tower 10m (~35 feet) in height or beyond. Physics tells us that apart from bearing the weight load downwards, the point of greatest strain (urge to tip over) on an antenna mast that is not free-standing is at its highest point of bracing. A free-standing mast that has no bracing or guy wires has all its points of strain occurring down where it leaves the concrete. For that reason, manufacturers make the bases of free-stading masts very stout. A non-free-standing mast will experience its maximum tipping strain at the connection point of its top guy wires, or at the location where it is bolted onto a roof end joist if no guy wires are used.

For a very Canadian example, hold a hockey stick above your head. No big deal, right? Now tape your skates onto the blade of the hockey stick and hold it above your head again. Notice that while the weight of the stick is on your lower hand, the strain of keeping it straight upwards is on your upper hand. That is the same tipping force felt by the top-most antenna mount guy wires and/or bracing point brackets.
What materials are recommended for building a mast or mount?
Choice of materials is critical when creating your pole or mast plans. For non-welded assembly (using nuts & bolts) your best bet is 1.5" O.D. galvanized steel conduit pipe (often called EMT for Electrical Metallic Tubing) which is common in major hardware stores in 4' to 12' lengths. It is known for its stiffness and rust/corrosion protection, as are galvanized or zinc-dipped fasteners. Welding galvanized steel is extrememly toxic so should only be done by a trained welder. If standard steel pipe is used it must be thoroughly coated in rustproofing paint before non-welded assembly or after welding. Try to use stainless steel fasteners for least corrosion. Some low-stress poles can be of extruded steel piping, but those are typically not strong enough for heavier antennas or rotor use. Plastics are not always strong enough for a pole or mast, but can be used in some situations as you can see in the ABS, PVC and other plastics for structural parts thread. Avoid using wood outdoors (even if coated) as it is subject to mildew, rot, and breakage. Pressure-treated lumber has copper product on it so must be avoided due to its mild signal-reflection properties.
Is there danger of a lightning strike or other such problem?
While direct lightning strikes on homes with outdoor antennas are exceedingly rare, it is still important to ensure proper grounding of your outdoor OTA gear since nearby strikes can create bursts of electromagnetic interference that could damage sensitive equipment. It is not only sensible to ground your gear properly but it is also necessary for proper home insurance protection and to meet your local electrical code. The Grounding Info & Standards: OTA/Dish/CATV/Telecom thread has everything you'll need to know about it.
Should I tilt my antenna up or down?
Most people can simply mount an antenna without tilting it, although in deep to deepest fringe areas it may sometimes be helpful to tilt the antenna upwards a bit. Pointing the antenna downwards is not an option. Sometimes there are situations in which the line-of-sight from an antenna to a broadcast antenna up on a mountain or tower is upwards, in which case tilting the antenna to match that line makes sense. The Tilting Antenna for Better Reception thread is dedicated to this topic.
Can I mount my antenna sideways to save space?
All TV antennas for use in North America must be mounted exactly as per their instructions, which ensures that they are receiving signals horizontally. If you tip the antenna on its side it would now be vertically polarized. The reason vertical orientation won't work is that the originating signals from all North American TV stations are polarized in the horizontal plain (in some parts of the world TV was in the vertical plain but I think that's not so anymore) so a vertical antenna is only capable of picking up just the tiniest slice of signal per wave. In computer modeling of antennas for North America the vertical parts of a reflector mesh are almost dead of signal even while the horizontal segments are booming with signal.
Can I put my antenna up in a tree?
Nearby trees can be a problem for UHF reception, although VHF signals are much more succesful at penetrating trees and forests. Trees should never be used for mounting antennas, as discussed in the OTA: The Big Trees Factor thread.
Can I run Cable TV and OTA on the same coax line?
You cannot have Cable TV signals on the same coaxial cable as OTA TV signals. They use the same frequency bands so they would interfere with each other, if not cancel each other out on certain channels. Further, there would be a high risk of signal leakage, which is treated very seriously by the authorities. For more information see the Signal Leakage Between CATV and OTA FAQ.
Any other tips?
Always remember the old saying that what goes up must come down, so double check all the mount points and fittings for solid security. Some minor installations can be done alone, but it is always better to have an assistant for any job requiring rooftop, ladder, or climbing work. Do not mount an antenna within 2m (6 feet) of an overhead electrical utility line.

Last edited by stampeder; 2010-09-07 at 10:24 AM.
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