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30m Vertical L
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A vertical with a single elevated radial is simple, and provides a modest amount of directivity.
A description can be found in ON4UN's Low-Band DXing (4th Edition pg. 9-21).
Click on a thumbnail below to see a larger picture
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The coax to wire connections. |
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The vertical section is simulated as 7.3m, but cut to 95% of that (6.935m), to compensate for the dielectric constant of the fishing pole. |
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The 6m fishing pole and mast. The vertical wire is spiral-wound on the fishing pole to fit 6.935m onto the 6m pole. |
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The top of this particular antenna is 15.25m (50ft) above ground. |
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The single radial slopes down to the south, and is tied off to the garden shed with kite string. |
Simulations
The antenna was simulated using EZNEC by W7EL.
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The supporting pole could be insulated, but at this frequency only a very small current flows in the supporting pole. |
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The 3D plot. |
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The 2D plot. |
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The simulated SWR. |
The following measurements were made with a N2PK VNA using VNA4Win software.
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The first SWR measurement showing resonance at 10.53MHz. |
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The SWR shifted into the band by adding 44cm to the radial. |
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