[600MRG] A dilemma....

[Marten T Beels]

On a related note, I found this page regarding calculating the total 
electrical length of an antenna with lumped circuit elements.

http://w5dxp.com/aircore/aircore.htm

The essential idea is that a certain amount of phase is accumulated at 
discontinuities in the impedance.  So to calculate the total electrical 
length of a dipole with a trap somewhere in the middle you'd need to 
know the impedance of the first (central) part of the dipole before the 
trap, the impedance of the trap, and the impedance of the second (outer) 
part of the dipole.

The bit I haven't found how to calculate is the impedance at the end of 
the central part of the dipole.  It is possible to model, but it would 
be nice to find some approximate formula.

Marten
K3HUW