[Antennas] Tower Installation

Thu Oct 1 13:23:29 EDT 2009

Chris Boone wrote:
>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...
>Then what is an inverted VEE with a 90 degree apex angle. balanced or 
un balanced? It's a vertical with one radial elevated above ground and 
semi up side down,
>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)..
>the 120 is to try to remove the ground losses, it has nothing to do with 
the antenna itself, the exact same antenna if it was raised so that the 
radials were like 10 to 20 feet above the ground, it would be just as 
effective or even better than the 120 radial version but with only 4 
radials.
>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.
>>Uhh why can you not do that? The old timers all did it in the past 
before coax became cheap. same with broadcast TV reception, until say 
the late 60's or so ALL TV was open line fed.
>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
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