[TowerTalk] Best Coax

[Tom Rauch]

> 
> K7LXC@aol.com wrote:
> 
> > >  Remember that these dB's are only for Transmitting, not Receiving.
> 
> >        Hmm. You've got to explain that to me. I thought they were the
> >        same
> > attenuation.
> 
> Except that on HF, the receiving noise floor is set by band noise; hence,
> no benefit to extra receive DBs.

Well said Steve!

At HF directivity affects receiving S/N noise. Gain does not matter 
unless gain is so far negative (through losses) that the system 
limits on internal noise. That would require a whole lot of system 
loss!

I typically use antennas for receiving with -20 dB gain, but very high 
directivity. They receive much better than high gain antennas with 
modest directivity.

For receiving, look for a narrow clean pattern and don't worry about 
gain unless it is minus 10 dB or more. For transmitting, look for 
maximum energy (gain) in the desired direction no matter how 
clean the pattern is.

    
73, Tom W8JI
w8ji@contesting.com

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