ARLA/CLUSTER: Antena J para os 10m simples

[Gomes]

Bom dia

Acho piada a estes esquemas onde se usam cabos coaxiais... x cm, y 
comprimento mas nunca se refere o factor de velocidade do cabo usado e 
depois dá asneira.

73, Gomes op: CT1HIX
https://ct1hix.net/

Às 11:14 de 05/08/19, João Costa > CT1FBF escreveu:
>
>
> I'm trying to build a 1/2 wave "Coaxial J-Pole" antenna, similar to 
> what is described here 
> <http://members.upc.nl/a.vrijswijk/documents/42.html>:
>
> Coaxial J-Pole
>
> Such an antenna would be great for stringing up in a tree when 
> operating remotely, no tuner needed.
>
> The trick is that I'm trying to use 75Ω RG6 coax for the matching 
> section (because it is relatively inexpensive and low-loss), but I 
> want a 50Ω impedance at the feed point.
>
> There are many single-stub matching network calculators, but almost 
> all of them assume that the impedance of the matching network is the 
> same as the feed point impedance. I know that such a matching network 
> is possible because that is exactly what the traditional j-pole 
> antenna is: a single-stub impedance transformer feeding a half-wave 
> antenna, where the matching section impedance doesn't match the feed 
> point impedance.
>
> Succinctly: How can I calculate the physical parameters of a 
> single-stub impedance transformer when the matching section impedance 
> doesn't match either the feed point impedance or the load impedance?
>
> antenna-theory 
> <https://ham.stackexchange.com/questions/tagged/antenna-theory> 
> impedance <https://ham.stackexchange.com/questions/tagged/impedance> 
> coaxial-cable 
> <https://ham.stackexchange.com/questions/tagged/coaxial-cable>
>
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