[Towertalk] Grounding mast to tower

[n4kg@juno.com]

On Tue, 2 Apr 2002 Pete Goudreau <goudpj@mac.com> writes:

>    SNIP
> 
> The other  half  of my original question was in wondering 
> how effectively capacitance  of the antennae and mast is 
> coupled to the top of the tower for use  in shunt loading 
> it as a vertical.  

> Pete, AD5HD

Very effectively.  See my article on Reverse Fed Elevated GP
Antennas in QST for JUNE 1994 or any of the subsequent
ARRL Antenna Books or ARRL Handbooks.  Of course
the antenna elements need to be connected to the boom
for maximum loading effect.

When I installed an 80M inverted vee fed with ladderline
spaced away from my 140 ft R25 tower that is also fed
as an Elevated GP on 160M, the 160M tuning was severely
impacted indicating that capacitive coupling of insulated
conductors can still load a vertical.  I merely tune for
maximum output (my 3-500 based amplifiers don't mind
the SWR).  Performance on 160M seems to be enhanced
with the 80M Inverted Vee providing additional loading.

Tom  N4KG

________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today!  For your FREE software, visit:
http://dl.www.juno.com/get/web/.