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

Hi Zvi,

A couple of comments--these are pretty much common-sense things but
sometimes overlooked.

First, yes, if the noise, or a significant part of the noise, is coming from
directions other than the signal of interest, you can improve signal to
noise ratio by using an antenna that accentuates the signal direction at the
expense of other directions. That makes a Yagi useful for reception as well
as for transmitting.

Second, if the noise is not a fully developed electromagnetic wave, but for
example a strong electric field from a brush-type electric motor that's very
near your antenna, then you can attenuate the noise by using an antenna
that's insensitive to electric-only fields (such as a properly designed,
constructed and installed small loop).

Cheers,
Tom

-----Original Message-----
From: nec-list-bounces+tom_bruhns=agilent.com_at_robomod.net
[mailto:nec-list-bounces+tom_bruhns=agilent.com_at_robomod.net] On Behalf Of
zvi frank
Sent: Wednesday, January 25, 2006 5:30 PM
To: nec-list_at_robomod.net
Subject: NEC-LIST: High Frequency Signal to Noise problem

-----Original Message-----
From: zvi frank
Sent: Monday, January 23, 2006 11:57 AM
To: nec-list_at_robomod.net
Subject:
 
Hallo All,
            I have a problem at H.F. 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 ?
    Thanks in advance,
                             Zvi

-- 
The NEC-List mailing list
NEC-List_at_robomod.net
http://www.robomod.net/mailman/listinfo/nec-list