[mythtv-users] Antennas

[Daryl McDonald]

On Fri, Nov 15, 2013 at 12:23 PM, Joseph Fry <joe at thefrys.com> wrote:
>> My antenna (homemade) is supported by 3/4" pvc conduit, 3' into the
>> ground and attached to the eave trough support and tethered with guy
>> ropes. In windy conditions I have observed sway of 2", maybe 3" with
>> little or no effect on my signal. I would bet your tree will have
>
> PVC makes a great mast for a short period of time (maybe a couple of
> years).  It becomes very brittle when exposed to prolonged UV light.
> A coat of Krylon or similar paint helps immensely.
>
>> greater sway, which is likely to have adverse effect for you. What
>> happens when your tree grows and bursts your zip ties, or whatever
>> fasteners you might use?
>
> Last I checked, trees grow by adding layers to the outside, not by
> expanding.  Typically a tree will simply grow around a fastener rather
> than bursting it.  Though zip ties my still burst as most fare even
> worse when exposed to UV.
>
> Putting an antenna in a tall tree is actually a very doable solution
> assuming you have a suitable tree.  You will still want a mast that
> lifts the antenna above the foliage, and be prepared to adjust it
> annually, but I know for a fact that many old HAM's and CB junkies
> would do exactly that if they had a nice tall straight pine that was
> easily climbed.
>
> As far as wind causing swaying impacting your reception... I wouldn't
> worry about it unless your in a deep fringe area, using a highly
> directional antenna, where being a few degrees off will kill your
> signal.  What wind may do is cause interference, and it won't matter
> if your in the tree or not.  There are three known/assumed causes of
> wind related interference.  First is that it increases scatter
> radiation (weak signals reflected off leaves of other trees, etc)
> which makes for an ever changing multipath signal that the tuner
> simply can't compensate for.   The other is that wind may cause an
> increase the amount of static buildup on your antenna/mast and other
> surrounding surfaces; this buildup and subsequent discharge is what
> some believe causes wind related dropouts.  Finally, when wind blows
> it stirs up dust/pollen/water droplets/etc., even a small amount of
> particulates in the air can impact reception.
>
> I would say that if putting the antenna in a tree will give you line
> of sight that you wouldn't be able to achieve with an affordable and
> typical mounting solution , then put it in the tree.  Getting above
> the treetops and achieving line of sight will help you more than
> having an antenna that doesn't move at all but must penetrate trees or
> rely on defraction/scatter to lock a signal... both of which would be
> far more subject to problems with wind.  If you can simply mount the
> antenna to your roof and have line of sight, than put it on the roof,
> far easier to service there.
>
> JUST BE SURE TO GROUND YOUR ANTENNA AND MAST!!!!
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Thanks for the suggestion Joseph, how would you recommend grounding
it? As it stands, pun intended, the two terminals of the antenna run
inside the conduit on stranded copper lamp wire, and into the house. I
haven't grounded it as yet not knowing how to achieve a good ground
without interfering with the signal. Maybe a separate lightning rod,
mounted higher than the antenna, and copper to the ground?