Topband: tree losses

[jim rogers]

Carl et al,

Interesting, my 80M full size (66') sloper comes within about 5 ft of a 
dogwood tree and it is dying. The sloped is fed 8' AGL with 2 full size 
elevated radials and about 500w and the dogwood is dying from that 
height(8') to the top of the tree at about 15'. Unfortunately for me, my 
XYL pointed this out to me - not good. The sloper has been in that 
position for about 1 year, before that the tree was doing fine.

Coincidence?

Jim N4DU


On 8/4/13 9:42 PM, ZR wrote:
> I cant think of anyone claiming a tree is resonant on any particular 
> frequency but that doesnt mean it cant be used as an antenna. Anyone 
> disagreeing with that should discuss it with the military who have 
> been loading trees for decades for emergency communications; in the 
> 3-8MHz range if I remember and going back as far as the 50's. Read the 
> old CQ and QST's.
>
> On another note I spent most of today outside doing tree trimming and 
> other sweaty exercises. I noted that my best producing Bartlett pear 
> tree was dead at the top and also a bit down on one side. Now it may 
> be just coincidence but the 80M sloper passes about 5' from the 
> farthest out branches and the end is exactly at the same height as the 
> tree top.
> This antenna is used at the vintage gear bench and also on the one for 
> amp repairs where Ive been hitting it rather hard this year with AM 
> with serious carrier power; the most recent being an Alpha 77SX.
>
> I also remember wilting the top of a sugar maple about 20 years ago 
> with 1200W on 6M to a 6/6 yagi array. After I moved the antenna to 
> another tower the tree recovered the following year.
> Another coincidence?
>
> Carl
> KM1H
>
>
> ----- Original Message ----- From: "Rudy Severns" <rseverns at gmail.com>
> To: "Topband" <topband at contesting.com>
> Sent: Sunday, August 04, 2013 5:39 PM
> Subject: Topband: tree losses
>
>
>> Tom's correct, the issue is not "resonance" but rather what, if 
>> anything,
>> happens when you have a so-so conductor/insulator (a tree) in the 
>> near-field and/or further out. Do the losses matter?
>>
>> Performing a definitive set of experiments would be a serious 
>> undertaking. I've fiddled around a bit but not much more than the 
>> tree conductivity work mentioned earlier.
>>
>> At this point I'm an agnostic: we really don't have good data. There 
>> are a number of Vietnam era papers on trees as antennas and 
>> propagation through jungle but most of that was at frequencies well 
>> above 160m.
>>
>> Here's a challenge for experimenters that'll keep you busy and out of 
>> the
>> bars.
>>
>> 73, Rudy N6LF
>>
>>
>> _________________
>> Topband Reflector
>>
>>
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