[VHFcontesting] Trees, et al

STEVE NOTEBOOK stephen.tripp at snet.net
Fri Jul 22 13:35:51 EDT 2016

Tree attenuation has been studied quite a bit.  I am on vaca but I do have 
an old 2way radio paper on this from Motorola which is great with simple 
answers and examples.
The main factor is the type of vegetation and how much water they will hold. 
At high frequencies the leaves can become quarter or half way reflectors.
Pine trees probably are the worse offender for absorbing RF as Steve 
mentioned.  Google tree attenuation to see some engineering studies that are 
hard to make sense of
unless you are and Engineer.

Steve, you are correct about Cellular RF  seasonal adjustments.  Cellular 
has come a long way since I retired in 2001 as a Cell Engineer.
They not only adjust power but the antennas have electrical beam tilt. I 
happen to own a cell site and a couple of weeks ago AT&T changed out
the 3 band panel antennas to 4 band both fed with fiber optics and powered 
by top mounted amps. The new panel antennas can weigh as much as 180lbs.
The frequencies AT&T are using range from 700mhz  to over 2ghz. The cell 
tower is 150' away from my ham towers and you can imagine the amount of 
I have.  Cell technology is difficult to keep up with AT&T going from 
Analog, TDMA, GSM and now LTE. It is so great we got to keep a portion of 
the 47ghz band with the Cell companies
attempting to take OUR UHF frequencies, so lets use them to save our bands.

Thanks for listening.
Steve K1IIG

Yes, trees make a difference.  Especially at higher freqs.  I have pine
trees on a couple of sides of my QTH that are over 100'. Getting through
them on 902 is tough, nearly impossible on 1.2 and 2.3.  I'm sure they
will affect the rest of the bands too although it might not be as
severe.  Regarding a tower, you got good advice regarding Rohn 45 vs.
25.  Sturdier and MUCH easier to climb I am told.  :)))  Cellular
engineers typically adjust power and coverage from winter to summer as
leaves come and go so this validates the issue with trees soaking up
RF.  I understand pine trees are especially bad for some reason.

Steve, N4JQQ, EM55bd
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