pine trees attenuate satellite dishes

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L. Daniel Rosa
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pine trees attenuate satellite dishes

Post by L. Daniel Rosa » Fri Aug 03, 2007 12:40 pm

Is this true? I heard it second or third hand from my neighbor. It sounds so believable that I want to accept it immediately, but my searches haven't turned up much of value. If anyone knows of an article please post a link.

mnboy
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Post by mnboy » Fri Aug 03, 2007 12:46 pm

I don't have satellite TV so I can't comment directly on that. But I have an XM radio. My back yard which is on the south side of my home is full of oak trees. So many that it's a canopy of leaves and very little sunlight gets through. Because of the trees my signal is low. I suspect it's because of the trees because before moving here, my backyard was clear and the signal was full.

Gary
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Post by Gary » Fri Aug 03, 2007 1:04 pm

Depends if the sap is running.

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haklesup
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Post by haklesup » Fri Aug 03, 2007 2:42 pm

Probably more general to say Microwave signals are blocked, scattered or attenuated by just about anything including trees and rain.

The degree to which a signal is disrupted depends a lot on its frequency. I know GPS is easily blocked by foliage. I think it is the water content of the leaves and wood more so than the solids that absorb most of the energy.

Don't you remember all those comcast commercials trashing satellite for how hard it was to install and how you had to cut your trees down to use it? OK, a bit bias but there's something.

http://ieeexplore.ieee.org/xpl/freeabs_ ... umber=7087

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dacflyer
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Post by dacflyer » Fri Aug 03, 2007 2:48 pm

yes trees will attenuate signals from dishes.. i had a friend that could not get a signal inthe spring because of the leaves and pines..but i had an idea that worked,, i attached his LNB to a larger dish,,one of them 3 ft dishes. i think it was primestar? they went out of buisness.. after doing this experiment, it actually worked, he went from a 10% signal to 86%
and this was trees in full leaf. i didn't know if it was gonna work or not,, but ,there was nothing to loose from the experiment. i just guessed that a bigger dish would catch more signal,and it did.. immagine what he would get with a 8 ft dish..lol:P

Robert Reed
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Post by Robert Reed » Fri Aug 03, 2007 4:15 pm

Before we had cable TV, all our off the air stations came from the same direction (and about 40 miles away)and had to pass thru a dense stand of hardwoods about 100 ft, high. Much better reception in the winter than in the summer.I've always known that trees eat up radio waves and basically due to the moisture content and this is mainly in the foliage, so this came as no surprise to me. What was surprising is that there wasn't near as much differential as I thought there would be. These were VHF stations though and absorbtion get increasingly worse with decreasing wavelength, so I can imagine much greater problems at satelite frequencys.

L. Daniel Rosa
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Post by L. Daniel Rosa » Fri Aug 03, 2007 7:26 pm

I already knew that anything biological would interfere. What I heard is that pine trees attenuate substantially more than other species. When I heard this I was eager to believe it for reasons I am not ready to disclose. Thanks for the input so far, and I hope for more.

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Chris Smith
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Post by Chris Smith » Fri Aug 03, 2007 7:40 pm

Absolutely, I have been dealing with this for years on both the high speed satellite and Direct TV, and pine trees definitely can block the MW signals.

Just lately they installed the slower 900 MHZ dishes and the problem goes away.

[Less attenuation]

However like one dish [of many] put in several years back, in a direct line with one pine tree that grew between the tower pick up and the dish element, ..... to this day it never worked, and was just replaced a few weeks ago with the slower 900mhz that works fine.

Also the dish units [24g?] hate pine trees, with or with out snow, and the signal level can drop way below the 50% level and drop out all together simple because the tree grew after the installation was put in place, or the snow makes it sag into the path.

The answer is yes, despite all the rhetoric that you will hear.

I have personally delt with these troubles for the last decade, and they do exist.

Most all of ours is Juniper, pine like trees. [Pine as well]

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Post by dyarker » Fri Aug 03, 2007 9:55 pm

All correct. Maybe this will help:
http://en.wikipedia.org/wiki/Line-of-sight

In the example given by dacflyer it looks like those trees caused a 8dB to 10dB attenuation. A 36 inch dish has 4 times the area of an 18 inch dish, so there is 4 times the signal power getting to the LNB antenna. That would be a 6dB gain.

If the tree can be trimmed (without ruining it's shape) to improve the line of sight, seasonal fade will be reduced.

Sometimes additional amplification can be used to increase signal strength to the receiver. This method is limited because more amplification generally worsens the signal to ratio.

If pines are worse than other types of trees, maybe it's because needles are more like parasitic antennas than flat leaves????? Water, "sugars" and "salts" content would be about the same, making conductivity and microwave absorption about the same.
Dale Y

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jwax
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Post by jwax » Sun Aug 05, 2007 7:53 am

"Are you saying coconuts migrate?"
(Sorry)
Are you saying pine needles act like chaff?
True to some extent! Their attenuation goes right up into the infrared spectrum. Good to remember the next time a police chopper with nightvision is looking for you on the ground- hide under a pine tree! :grin:

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