[antennaware] Antenna for 80M!

[Gary Breed]

Mike

The feedpoint impedance of a vertically polarized delta loop will
vary with the shape.  If it is not too high -- the bottom wire is long
and the corner angles are acute -- the impedance may be near
50 ohms, or even a bit lower.  Also, if you have sloped the antenna
so the bottom wire is away from the bottom of the tower, it will
affect the feedpoint impedance.

I suggest that you model the antenna exactly as you will build it
and select the exact location of the feedpoint for the best combination
of impedance and radiation pattern.  i.e., try feeding it at a lower
corner and at a couple points in the lower 25% of the side wires.

You may find that a direct 50 ohm feed will work.  Or, you may
find the best location to will transform through the 75 ohm line to 
a low SWR.  

73, Gary K9AY

--------------

>
>Hi again!
>
>When making a vertical deltaloop i should have 1/4 75ohm coax before
>connectening it to the 50ohm cabel, is that right?
>
>Thanks for the tips!
>73 de sm3wmv / Mike!
>



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