Vhf antenna help, please...

[Neal]

I am thinking of moving my antenna from the very top of the mast and resiting it on one of the spreaders.

As the boat is gaff rigged, the loss in height would only be about 5 feet.

The move would also mean that the antenna will be partially screened by the solid wooden mast (about 7 inches diameter at spreader height), and by the cap shroud (of about 3 eighths of an inch diameter).

Is either the loss of height, or the mast and cap shrouds, likely to have a signifcant impact on vhf performance?

Many thanks for any advice.

Regards,

Neal

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[Bergman]

No

Should be fine



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[Strathglass]

The height change will make an insignificent difference.

The proximity to your woodem mast will make some difference (but not very much) when it is very wet.

But the proximity of a shroud running parallel to a VHF aerial may affect both the performance on transmit and recieve and alter impedance presented to the VHF set.

Iain





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[William_H]

The short answer is possibly not much. Radio transmission and reception operates on a logarithmic function so that a doubling or halving of power is only just perceptible in loudness or range. The mast should not effect the operation much however the presence of the stay may mean it works better off one beam than the other. Consider that TV aerials put a reflector behind and a director in front of the actual antenna to give a gain in one direction and attenuation in the other directions. The directors are only pieces of conductive material paralell to the antenna and a short distance away so it is likely the stay will have a similar effect. mount the antenna closer to the mast than the stay but I would think you would need a good reason to move it at all. regards will

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