[TowerTalk] Modeling a self supporting tower interaction

[Mike Fatchett W0MU]

Math is hard!  LOL

Thanks

W0MU

On 6/25/2024 10:56 AM, Leeson wrote:
> From "Physical Design of Yagi Antennas," ARRL 1992, pg. 9-2:
>
> "This problem is resolved in a short paper by Jaggard [D. Jaggard, "On 
> Bounding the Equivalent Radius," IEEE Trans AP, Vol. AP-28, May 1980, 
> pp. 384-388, https://ieeexplore.ieee.org/document/1142336] Jaggard 
> shows that the equivalent radius ae of a noncircular shape must lie 
> between the radii ai and ac of the inscribed and circumscribed circles 
> which geometrically bound the noncircular conductor. Further, he shows 
> that these bounds can be narrowed by the use of radii ain and aout 
> which are the radii of circles of the area A and perimeter P of the 
> cross-section shape of the conductor, ain = sqrt(A/pi) and aout = 
> P/2pi. A satisfactory estimate for the equivalent radius is the mean 
> of the two bounding radii."
>
> A freely downloadable scan of my 1992 book with more details about the 
> equivalent radius of irregular shapes, "Physical Design of Yagi 
> Antennas," is at
> https://www.dropbox.com/s/hmhkeofz0igrg1e/Physical%20Design%20Of%20Yagi%20Antennas%20D%20B%20Leeson%20V2.pdf?dl=0 
>
>
> 73 de Dave, W6NL/HC8L
>
> On 6/25/24 5:40 AM, john at kk9a.com wrote:
>> To check for interaction, I have done the easy model method of using
>> a very thick wire for the tower.  Since the tower is triangular and a
>> wire model is round, I took a wild guess at the wire diameter. I
>> never thought of matching the surface area.
>>
>> John KK9A
>>
>>
>>
>>
>> Jim Lux wrote:
>>
>> There's two ways to approach the modeling.  The easiest is to model a
>> "very thick" wire - match the surface area of the tower with the
>> surface area of the wire.
>>
>>
>>
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>>
>>
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