[TowerTalk] Dipole Z Calculator

[jimlux]

Paul Christensen wrote:
> I am looking for any type of computational tool that will allow me to 
> quickly look at the terminal Z of a dipole in free space where I can change 
> its wavelength from 0.25 to say...approximately 7 wavelengths.
> 
> Anything like that available without getting into antenna modeling software?
> 
> 


Do you need an equation? or a table lookup? or a callable subroutine?

If you have matlab, or can translate matlab into your language of 
choice, Orfanidis's on-line electromagnetics text book has some matlab 
procedures that will give you feedpoint Z of arbitrary dipoles, using 
King's approximation.  You give length and diameter, and it gives you Z.

Somewhere around I have a excel spreadsheet with Z for 0.1 to 2.5 
wavelengths of a 10 meter long dipole using 1mm diameter conductors in 
steps of 0.05 wavelength. I could regenerate it if needed for a longer 
range or finer steps.