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

dear Frank,

Also, we experience often that small loop, shielded loop has
better S/N ratio over horizontal dipole on lower end of HF or MF,
where receiver noise (internal noise) is not a factor.

Hideho YAMAMURA, JF1DMQ/AA6VE

>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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