Well ... you made your statement (that even a good receiver needs a
resonant antenna, and you were talking about how you could hear stations
breaking in that nobody else could, remember?) to the list so I replied
to the list. How is that wrong? If I reply to you offline others on
the list won't realize that you are wrong and the erroneous impressions
about resonant antennas never die as they should.
But, yes ... there is something inherently wrong with your impression
that an antenna system that facilitates maximum transfer of power will
also be the best receive antenna. If you reread my comment below you
will see that maximum signal-to-noise ratio ... not maximum signal and
noise combined ... is what makes a better receive antenna. There is
lots of information on the topic of receive antennas all over the
internet. You can either research it yourself so that you are able to
understand it or not ... your choice.
Dave AB7E
On 11/13/2012 9:25 PM, Richard Fjeld wrote:
> Okay, digest this; my budget allows an 80 meter delta loop fed with
> open wire and I tune it with a manual tuner. As far as my radio is
> concerned, it looks at a resonant antenna system allowing a maximum
> transfer of power on both transmit and receive. Any fault with that
> statement?
>
> We are way off the original post which was asking why he had to "to
> engage the 20 dB preamp on the K3 to get it to hear an S9 signal at
> the appropriate level of other receivers?"
>
> Now I know why people reply off line.
>
> Rich, n0ce
>
> ----- Original Message ----- From: "David Gilbert"
> <xda...@cis-broadband.com>
> To: <elecraft@mailman.qth.net>
> Sent: Tuesday, November 13, 2012 6:12 PM
> Subject: Re: [Elecraft] K3 sensitivity below 40 meters
>
>
>>
>> Even that misses the point, I'm afraid. Remember that the original
>> comment referred to the receive capability of an antenna.
>>
>> The only thing that matching or "tuning to resonance" does is improve
>> the amplitude of the combined signal and noise feeding the rig ... it
>> does not improve the signal to noise ratio. A good receiving antenna,
>> however, has some pattern to it that captures the desired signal while
>> discriminating against unwanted noise, whether the noise is man made or
>> atmospheric. A Beverage antenna, for example, has quite a strong
>> pattern in one direction so it has a good signal to noise ratio feeding
>> the rig. A Beverage is pretty inefficient, though, and the desired
>> signal is pretty weak, so typically a matching transformer (9:1 or so)
>> is used to optimize the signal transfer and a low noise preamp (either
>> in the rig or external) is also used ... but the signal to noise ratio
>> is determined by the antenna independent of whether it is matched or
>> not. I guarantee that an unmatched Beverage with enough low noise gain
>> after it will outperform any practical resonant or matched ("tuned to
>> resonance") antenna available to hams.
>>
>> 73,
>> Dave AB7E
>>
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