[Elecraft] Random wires

[David Gilbert]

Wrong again ... the folded element transforms the ground resistance 
right along with the radiation resistance.

Look at it this way.  Both the radiation resistance and the ground 
resistance are present in combination at the feedpoint of a normal 
monopole.  Folding the element merely makes an relatively efficient 
transformation of what is already there at the feedpoint.  The folded 
element is essentially nothing other than a transmission line, and it 
has no way of knowing where that which it sees at one end came from.  it 
doesn't distinguish between the components.

Dave   AB7E



On 10/1/2013 2:48 PM, Ron D'Eau Claire 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
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Roger D Johnson
> Sent: Tuesday, October 01, 2013 12:41 PM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] Random wires
>
> This is NOT true! It merely raises the feedpoint impedance...just the same
> as adding a
> 4-1 transformer.
>
> 73, Roger
>
>
> On 10/1/2013 3:10 PM, Barry LaZar wrote:
>>
>>      As I read your post, I infer that at the moment you are wanting to
>> add 160 meters to your capability. An antenna that I have used and
>> liked is the Twin Lead Marconi. It's a simple, cheap, and effective
>> antenna. I first saw it written up by Bill Orr years ago. The premise
>> of the design is that a quarter wave antenna driven against ground may
>> not be the most efficient antenna due to low radiation resistance.
>> Therefore, raise the radiation resistance by using the theory of a
>> folded dipole. The folded element raises the radiation resistance by a
>> factor of 4 for 2 elements as the impedance changes as the square of
>> the number of elements. You will still need radials, but your ground
> losses will decrease.
>>
>> 73,
>> Barry
>> K3NDM
>>
>>
> --
> Remember the Liberty (AGTR-5)
> http://www.usslibertyveterans.org/
> http://www.gtr5.com/
>
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