[TowerTalk] Dipole fed with balanced line?

[Ken]

On Jan 17, 2012, at 10:52 AM, Paul Christensen wrote:

> With top loading for verticals, or end-loading for dipoles, super high 
> efficiency can be maintained.  I would start by reading Sevick's work as a 
> general analysis of shortened antennas, and also study how and why a 
> radiator's feedpoint Z, I, and E changes with radiator length.


Paul,

THERE I agree with you because the high current portion (e.g. center portion of a dipole, or the "effective" quarter wave portion of a vertical) is used as a radiator.  End loading works well because the high current section of a half wave is still the radiator), but just using the ends of a dipole (e.g. center loading,etc.) is not nearly as effective.   

Shortening a half wave dipole, without end loading, significantly reduces it's efficiency. 

A 70' dipole used on 80m without end loading is much less efficient of a radiator than the same antenna with end loading.   And the simplest way to end load such an antenna is to add about 30' of wire on each end ;-)  

Ken  WA8JXM