[TowerTalk] How much do trees really affect verticals

[Gedas]

Hello all....very interesting subject.  I am trying to DL the PDF mentioned 
in the article below from ITS "paper by A.G.Longley at the U.S. Dept. of 
Commerce" but not having any luck at all.  Even searches are not working for 
me for some reason WRT that document.  Can someone who has DL'ed that PDF 
pse send it to me?  TU !  73

Gedas, W8BYA

Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

----- Original Message ----- 
From: "Larry Banks" <larryb.w1dyj at verizon.net>
To: "Ham - Tower Talk" <towertalk at contesting.com>
Sent: Monday, August 25, 2014 9:54 AM
Subject: Re: [TowerTalk] How much do trees really affect verticals


> Hi Gregg,
>
> I asked this same question a couple of years ago -- of the QST's "The 
> Doctor Is In." Here are the answers I received.
>
> 73 -- Larry -- W1DYJ
>
>
>
>
> ------------------------
> Hi Joel and  Larry
>
> Everyone appears to have an opinion on this subject but definitive 
> scientific works are more difficult to find - at least on the Internet. 
> From a practical observational standpoint, I have found that low band 
> verticals particularly 80 and 160 do not seem to be bothered by deciduous 
> hardwood trees. However I used these during contests that occurred mainly 
> in the colder months though I am reasonably sure that the sap has NOT 
> drained by the end of October and I never noticed a difference between 
> late October [leaves have turned but half of them are still ON the trees] 
> and February [leaves gone and sap drained if it really does drain in MD].
>
> My station has all its yagi antennas mounted on a 24 ft mast beginning on 
> top of an 83 ft tower on a 1/4 acre lot. The good news is that the tower 
> sits at the edge of a group of hardwood trees so it is nearly invisible in 
> spite of its size. The bad news is that the trees, once 70 ft tall are now 
> approaching 90-100 ft range. I don't think the trees bother my HF 
> tribander at 83 ft. Or my 7 el 6 meter beam at 87 ft. But the 2 meter beam 
> at 95 ft may be impacted. I think my 2 m signal on moonrise/moonset EME is 
> at least 3 dB below what it should be. I also think that at 432 and 
> above -especially above- trees are bad news [see below].
>
> The best reference I can give is section 2.3 [on p. 18] in a 1978 paper by 
> A.G.Longley at the U.S. Dept. of Commerce.
>
> < http://www.its.bldrdoc.gov/pub/ot/ot-78-144/ot-78-144.pdf >
>
> That paper and others that I have found agree that avoid trees entirely is 
> the best course. Anything at 100 MHz and more is unacceptably attenuated 
> by trees with non-deciduous pine trees being somewhat worse than deciduous 
> hardwoods. At HF the effect may be quite a bit less noticable. Verticals 
> at HF may be more affected but again the difference is only a very few dB 
> more. Pine trees at HF are worse for the reasons you have already noted.
>
> Therefore I would say if you are moving ... you need to take the dense 
> tree cover seriously. On 2 meters you will be impacted and above 2 meters 
> unless you are clear of the trees you may be severely impacted. I suspect 
> on 160 - 40 meters you won't have much trouble but a tribander buried in 
> the trees is also likely to see some attenuation - maybe more than you'd 
> be comfortable with. The same with 6 meters. For less dense trees I think 
> the tribander and 6 meters would be o.k.
>
> Good luck.
>
> 73 Gene W3ZZ
> World Above 50 MHz
> FM19jd MD
> 50 => 10 GHz
> Grid Pirates Contest Group K8GP
> Member, CQWW Contest Advisory Group
>
> ----------------------------
> Hi, Guys:
>
> My understanding is that you'd have to put a vertical radiator very close 
> to a tree for sap/no-sap to have any impact on the antenna's 
> performance --  perhaps within a foot of the trunk. Having said that, I 
> know of several hams who did very well with "disguised, stealth" vertical 
> wires run right up alongside the trunks of substantial pine trees. These 
> gents worked lots of DX with such setups. Of course, YMMV!
>
> 73 and HNY,
>
> Dean, N6BV
> Senior Assistant Technical Editor, ARRL
> Editor, The ARRL Antenna Book
> -----Original Message-----
> From: Hallas, Joel W1ZR [mailto:W1zr at arrl.org]
> Sent: Tuesday, January 02, 2007 12:24 PM
> To: Larry Banks
> Cc: Straw, Dean, N6BV
> Subject: RE: Dear Doctor: Antennas and Trees
>
>
> -----------------------------------
> Larry,
>
> I haven’t seen definitive words on the topic, however I believe trees have 
> more of an effect for HF signals on vertically polarized signals then on 
> horizontally polarized ones. Floyd Koontz, in his Horiz Ewe article in Dec 
> 06 QST asserts that sap flow makes a difference and that if the sap drains 
> in winter there is less of an effect on signals. This makes some sense, 
> although I’m not sure why trees with wide branches wouldn’t have similar 
> effect on a horiz component.
>
> I am copying ARRL Antenna Book editor Dean Straw, N6BV, in case he has any 
> thoughts,
>
> Regards, Joel
>
> Joel R. Hallas, W1ZR
> Technical Editor, QST
> American Radio Relay League
> The national association for AMATEUR RADIO
> TuTh;  860-594-0393
> MWF; 203-226-7353
>
>
>
>
>
> -----Original Message----- 
> From: k9kl
> Sent: Sunday, August 24, 2014 22:22
> To: TowerTalk at contesting.com
> Subject: [TowerTalk] How much do trees really affect verticals
>
> I have been clearing some land to plant more maple trees for my sugar bush 
> to make maple syrup in the spring.  While I resting I thought of all the 
> room I am clearing for a 4 square for 75/80. There are 40 some deciduous 
> trees on the land which is about 150 feet by 350 feet. Prime farmland, 
> stream bottom with about 4-5 feet of topsoil. Its about 200 feet from my 
> house/shack.
> How much are those trees really going to affect the antennas?
>
> Gregg K9KL
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>