[Elecraft] Random wires

Bob Cunnings nw8l at whitemesa.com
Tue Oct 1 22:55:24 EDT 2013


Here's a link to the W8JI radiation resistance topic:

http://www.w8ji.com/radiation_resistance.htm

where the antenna efficiency issue is analyzed - using a 1/4 long
folded radiator as the example. In this analysis the antenna efficiency
is unchanged because total power and ground loss power terms remain
constant.

Bob NW8L

On Tue, 1 Oct 2013 14:48:55 -0700
"Ron D'Eau Claire" <ron at cobi.biz> wrote:

> The important value is the resistance at the feed point of the
> radiator, independent of any matching devices used. 
> 
> Adding a 4:1 or other transformer is simply adjusting the impedance
> the feed line sees, like any other matching network you might use. It
> has no effect on the feed point resistance of the antenna. 
> 
> A 1/4 wave long folded radiator has a feed point resistance of 4x the
> typical 1/4 wavelength radiator, quite independent of the ground
> system. Hence the efficiency is higher. 
> 
> 73, Ron AC7AC
> 


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