ssd's experimental cylindrical parabolic dish


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close up of parabolic driven element, reflector, tangental guide
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experimental 1/4 wave 70cm cylindrical parabolic (circular 4' diameter)

Parabolic

This experimental modular parabolic antenna has some interesting features and flaws. This was extremely cheap and easy to construct! The goal was to determine the effectiveness and constructability of a minimal dish. The driven element is a commercially bought quarter wave 70cm antenna. The reflectors are what I estimated to be the smallest effective reflector -- just barely longer than the driven element. All are hung from a fiberglass rod tensioned into a semi-circle, balanced on strings hung from a single point.

This got about 10db gain (over the bare quarter wave antenna) when the driven element was in exactly the right spot. Unfortunately, this spot is very small and not where predicted, probably due to irregularities and the circular aberation. If I get rid of the hanging rod, I could hang them directly from the ceiling and get a true parabola, with possibly better effectiveness, but no ability to aim.

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