[TowerTalk] Hustler 6-BTV installation

[Roger (K8RI) on TT]

On 4/9/2014 10:04 AM, Brian Alsop wrote:
> I'm not sure one would ever notice the tree effects on HF.  There are 
> lots of other things (e.g., no balun at the feedpoint, feedline 
> routing and objects in the near field, ground terrain variations ) 
> that would probably be larger effects.

I have Satellite, and off the air TV.  Several trees grew into the 
"line-of-sight" between the antenna and UHF station.  It's not true that 
with digital you either receive, or don't receive the signal. The range 
between signal and no signal is much narrower than it was for VHF 
analog, but there is a range. We noticed that on occasion the signal 
would "pixelate" and pause. As time went on this happened more often.  I 
put the UHF antennas at roughly 90 feet on the 45G with a clear shot.  
Surprisingly, even with the longest antennas I could find, they do well 
up to 20 or 30 degrees off axis with a range in excess of 100 miles.  So 
at UHF, (including 440) the regular, leafed trees do have a strong 
attenuation of the signal. They seem to have little, if any effect on 
160 through 40.  I don't know about 20 through 10.

NOTE.  With one antenna pointed between Detroit and Lansing, I could 
receive both quite well, but had to move the antenna to get the Grand 
Rapids area.  With an antenna pointed to the NW I could receive both 
Cadillac and Traverse City (bout 70 and over 110 miles)and within 10 
degrees of each other.

Any vegetation seems to block the satellite signal.  Which is much 
higher in frequency.  The same goes for wireless Internet.

It's surprising how far away an antenna for 75 and 40 can be from others 
and still show effects even in SWR and resonant point although they were 
apparently not sensitive to trees.

A 40 meter vertical antenna (AV640)displayed shifts in the resonant 
frequency when slopers were erected several wavelengths distant. (50 to 
100 KHz)

The base of the AV640 is about 25 feet above ground.and 50-75 feet from 
the trees.

73

Roger (K8RI)

>
> I had an commercial BC TV engineer relate to me a story of the 
> importance of attenuation in "trees" for HDTV (UHF).  One station near 
> the NC coast (beaming inland) made an argument that the long leaf pine 
> needles were the right size to selectively attenuate their signal.  
> They managed to get a somewhat higher permitted power.  It would have 
> been interesting to actually have a measurement of the effect.......
>
> 73 de Brian/K3KO
>
>
> On 4/9/2014 13:52, john at kk9a.com wrote:
>> I have had great results with dipoles hung in trees.
>>
>> John KK9A
>>
>> To:    towertalk at contesting.com
>> Subject:     [TowerTalk] Fwd: Fwd: Hustler 6-BTV installation
>> From:     Hans Hammarquist <hanslg at aol.com>
>> Date:     Wed, 9 Apr 2014 00:02:05 -0400 (EDT)
>>
>> Have the same experience hanging various verticals from trees. I 
>> guess if you
>> have a perfect, non-conducting tree it will work. Unfortunately trees 
>> are
>> somewhat conducting, enough to mess up the radiation.
>>
>>
>> It will work better if you don't use a tree but a non-conducting 
>> support such
>> as a large plastic pipe. A thicker, self-supporting conductor such as 
>> a tube
>> would also work.
>>
>>
>> Maybe you get what you pay for.
>>
>>
>>
>> Best 73 de,
>>
>>
>> Hans - N2JFS
>>
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