[TowerTalk] Equation wanted

[charlieo@tellabs.com]

Greetings,

In the article "Designing a Vertical Antenna" from September, 1978 QST, written 
by Walter Schulz, K3OQF, an equation for determing the characteristic impedance 
of a vertical element is given as:

	Zo = 60 * (ln (2*h/a) -1)
	
	where h = length or height of element in inches
	      a = radius of element in inches
	      ln = natural log
	      
The article references this equation to Jasik, "Antenna Engineering Handbook", 
McGraw-Hill, Inc., 1961, p.19-3.

This equation appears to give adequate results for an element of constant 
diameter (and radius), at least in the context of the antenna construction 
article that it appears in.

My question for the assembled masses is:

Does anyone know of a similiar equation that takes into account a tapered 
element (i.e. non constant radii) ??

As usual, many thanks in advance!

73,

Charlie  N9CO	charlieo@tellabs.com

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