[TowerTalk] closeness to commercial building roof top

[n4kg@juno.com]

On Thu, 4 May 2000 12:44:33 -0500 brunet@us.ibm.com writes: 

	<SNIP>
> 
> Another complicating factor is a set of  nearby buildings 
> out in the area where the first reflections will occur in  the 
> NW quadrant.  My first rough analysis shows that the 
> low angle  reflections will hit these buildings after hitting 
> the ground so I assume the  radiation  in this direction 
> will only consist of the direct radiation and thus  the
> loss of the 6 dB doubling effect when the direct and 
> reflected rays  are in
> phase (and the nulls when they are out of phase).
> 
> Pete ws4g

YEP, loss of the ground reflection can result in a real 
deterioration of performance.  

I once had a 5L10 side mounted at 40 ft aimed at Europe.
This alignment was through my house, 100 ft away, with
an 18 ft piece of flashing at 20 ft.  This antenna was my
WORST choice to Europe in spite of being the biggest
antenna.  When I moved it to another tower at 45 ft but
with a CLEAR shot to Europe, it immediately became
my BEST antenna.

I have often wondered about the effects of shooting through
power lines.  To JA, my powerlines are 50, 125, and 200 ft
away from towers that are 40, 60, and 80 ft.  It is pretty
clear that NONE of the top antennas are as effective as
others who have clear shots.  When I rotated the 
aforementioned 45 ft high 5L10 to JA, (300 ft from the
power lines) it immediately became my best antenna in 
that direction.  Unfortunately, trees have grown to 50 ft 
very close to that tower and that 5L10 has been taken down.

de  Tom  N4KG


________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
http://dl.www.juno.com/get/tagj.

--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm