Quarter-wave lenght antenna shape
What you are describing is a Monopole Antenna. This should be perpendicular to your ground plane - that is pointing straight up into the air.

The radiation pattern for a monopole antenna is like this:

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That is seen from the side, so it actually looks a bit like a deformed doughnut:

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As you can see, the best signal strength is actually away from the antenna, not close to it. If you want better "close" coverage you can go for 3/4 wavelength which adds an extra bubble on top. Other lengths give even more bizarre shapes:

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In all cases the "shape" is a vertical rod.