Re: NEC-LIST: High Frequency Signal to Noise problem

At 8:30 PM -0500 1/25/06, zvi frank wrote:
>...Somebody told me he improved the S/N of an HF antenna. As far as
>I understand usually the S/N of an HF antenna is determined by
>external noise. This would mean improving the efficiency of the
>antenna would not increase the S/N. I suppose if the antenna was
>made more directional than one might be able to decrease noise
>coming from some directions. Has anyone any comments or experience
>with this sort of problem ?

1. The "signal" usually comes from one direction (or a narrow range
of directions), and most of the noise usually comes from other
directions or a wider range of directions; so antenna directivity can
increase the received S/N ratio.

2. HF signals received via skywave usually have random polarizations.
Very often, most of the noise arrives via ground-wave from relatively
nearby sources, so it is predominantly vertically polarized.
Therefore a horizontally polarized antenna tends to yield a higher
S/N ratio.

-Chuck W1HIS

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