RE: NEC-LIST:helical ant. modeling

At 9:29 AM +0200 10/4/01, Ian Roberts wrote:
>My hands-on with a 22 turn helical at 435 MHz highlighted two aspects:
>Helicals suffer severe gain saturation if constant radius/constant spacing
>is applied....
>The workaround I applied was to group turns of this helical into 10 at 1.1
>circumference for maximum gain, 6 at 1.0 circum, and the rest at .95
>circumference while maintaining the same spacing....

Never having tried to build a helical ant., I'm confused by this
description. I'd like to understand:

Are you varying the radius of the helix while maintaining the axial
spacing of turns? Which end of the helix has smaller radius?

Is a picture/drawing available?

Tnx -Chuck

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