[Antennas] Tower Installation

[Chris Boone]

I beg to differ somewhat....They are really unbalanced....as a groundplane
is not the same as the vertical radiator...Especially on folded monopoles
and other similar verticals...
IF the vertical is a vertical dipole, yes it is balanced...as the current
flow is in opposite directions and equal...

but a vertical with a ground system has the ground current flow 90deg to the
plane of the radiator...and is thus NOT really balanced in that
respect...Also with more radials, etc in the ground side than the single
vertical radiator, there is a difference in resistance and thus current
levels.....(Broadcast AM stations are required to have 120 1/4w radials at
minimum under EACH tower)..A balun at the base of a vertical is
useless....you really need a choke to prevent RF from snaking back down the
shield of the coax....but as for unbalanced to balanced, no, the vertical
sees no improvement with a balanced line..(If your statement were true, then
that means I could run balanced line to my mobile 2m or UHF 1/4w vertical??
I just cant see that happening and it makes no sense.

BTW before coax, EVERYTHING was fed with open line.....not because they were
balanced but because there was NO coax...I had a radio station fed with open
line to 4 towers.....what a mess!!! We eventually changed to Heliax and the
array became MUCH more stable...at the tower base, was a XFMR that made the
balanced line transform to the Unbalanced base of the vertical tower..When
we switched to Heliax, the transformers were removed.

Chris
WB5ITT
PG-9-5322
Broadcast Engineer for 35years
Society of Broadcast Engineers member (SBE)

> -----Original Message-----
> From: antennas-bounces at mailman.qth.net [mailto:antennas-
> bounces at mailman.qth.net] On Behalf Of Joe
> Sent: Thursday, October 01, 2009 11:40 AM
> To: whitaker at ieee.org; antennas at mailman.qth.net
> Subject: Re: [Antennas] Tower Installation
> 
> Umm  verticals are balanced also,, and prior to coax also were fed with
> open line.
> 
> Joe WB9SBD
> 
> C.Whitaker wrote:
> 
> >de wb2cpn
> >I prefer a balanced feed to a dipole because the dipole
> >is a balanced load.  I prefer coax to unbalanced things
> >like verticals etc.   I don't know if ARRL took a position
> >on feeds for dipoles, but lately they haven't been all that
> >technically on board on a few things.
> >73  Clete
> >