[TowerTalk] Tower resonant frequency

[Bob, W3IDT]

> https://www.kkn.net/dayton2008/multi-element%20lowband%20verticals%206.pdf

Also:
Antenna book / on4un book:

a. 4 or 5 bent verticals from tower.
    Initially from YCCC guys.
b. coaxes to center switch.
c. coax length to be inductive
    to create reflectors for non-fed vertical.

Also
Could use poles /  ropes / other outrigger
to move top of verticals from top of tower.

Am on PC at this ridiculous Eastern Time
for something else. Hence, no direct references.

Bob, w3idt



.............................
. Robert F. Teitel, W3IDT   .
.                           .
. W3IDT at arrl.net            .
. W3IDT at comcast.net         .
............................. 					

On 9/18/2020 8:35 AM, john at kk9a.com wrote:
> I am not sure how accurate this is but I usually model the tower as a 
> large diameter wire and I only include the boom of the top antenna (I 
> use insulated elements).  K9RS has an interesting article on using bent 
> wire verticals around a tower 
> https://www.kkn.net/dayton2008/multi-element%20lowband%20verticals%206.pdf
> 
> John KK9A
> 
> 
> k4xs wrote:
> 
> Plans are VERY slowly progressing for my new station in Belize.  Plans 
> are for a 106 foot tower with lots of goodies on it.
> Here's what is planned:106 ft of Rohn 55 guyed with Phillystran.  Three 
> swing armed  Skyhawks at 32, 64 and 96.  Two A3WS WARCs at around 76 and 
> 42 ft.  I plan on running four ropes to hold a wire 4 square surrounding 
> the tower.  This is similar to what I had in KH6 and the 4 square worked 
> well although the F/B was down to around 10-12 dB.
> My question is this:  I know the tower will have some effect on the 4 
> square surrounding it.  Obviously I don't want the tower to be anywhere 
> near resonant on 80.  My guess is the top loading of the tower will 
> lower the resonant frequency quite a bit, and the effective height will 
> be around 145-150 ft, but I am not sure.  Obviously if it is in the 
> range of around 130 it would be a big issue.
> There is not enough room to put up a 4 square by itself so I'm stuck 
> with this set up.  I do have some fiberglass poles that I could attach 
> to the tower vertically to give it another 13 feet or so by running a 
> wire up the pole and attaching it to the tower, but I really don't want 
> to do that if I don't have to.
> Thoughts on this?
> 
> 73  Bill K4XS/KH7XS
> 
> _______________________________________________
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> 
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