[VHFcontesting] Trees, et al

Roger Rehr W3SZ w3sz73 at gmail.com
Fri Jul 22 14:32:07 EDT 2016

You paid for it, so you might as well get to read it:



Roger Rehr W3SZ

On 7/22/16 1:35 PM, STEVE NOTEBOOK wrote:
> 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 filtering
> 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
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting at contesting.com
> http://lists.contesting.com/mailman/listinfo/vhfcontesting
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting at contesting.com
> http://lists.contesting.com/mailman/listinfo/vhfcontesting

More information about the VHFcontesting mailing list