[Moon-net] VHF Antenna Noisetemperature by YU1AW..

[Edward Cole]

Only made a quick and partial reading of the paper, but it appears 
the new paper addresses the T portion of the G/T figure of merit used 
in Lionel's study.  This would only result in a across the board 
shift in G/T numbers with the relationship between antennas remaining 
(as Graham says the ranking would would still hold).

For making better estimates of the Lunar path link it may have impact 
since it affects the outcome of total receive noise temperature.  An 
interesting paper that I will read completely as some point.  I have 
spent a great deal of time with NF analysis and path link formula.  I 
wrote a G/T spreadsheet some years ago for the SETI-League for 
antenna measurements using the sun.

In my (early) opinion this paper does not invalidate Lionel's work.

73, Ed - KL7UW

At 06:57 AM 4/17/2008, graham wrote:

>Bodo,
>
>
> >Does it means that the list of VE7BQH is more or less
> >an academic paper?
>
>It means that YU1AW does not agree with the chosen numbers to construct the
>table that BQH made.
>
>That does not invalidate the Table or the comparison for that given set of
>parameters.
>
>The BQH numbers where chosen as representative of an 'urban' qth (Tgnd) and
>representative of the lowest Tsky.
>
>If you look at Page 3 of AW's paper you will see a graphical representation
>of 'typical' noise temperatures, here you can see that even greater Tgnd
>numbers are predicted than those used by the BQH method.
>
>If you look at Page 10 you will see that AW proposes an even higher Tsky
>than that used in the BQH method.(In the new figure of merit proposal by AW)
>
>It seems the purpose if the AW paper is to introduce a more sophisticated
>way of quantifying and comparing Yagi antennas. Which of itself is fine and
>I agree this could be done.
>
>Although I have not spent the time to study the AW actual proposal in
>details (ie running models and numbers here) and what implications it might
>have in 'ranking' existing antennas. I would have expected such a paper to
>contain as a minimum 'several' worked examples ( it contains none at all).
>
>I did spend many weeks re_running the BQH Table on models with alternative
>numbers plugged in the Tsky and Tgnd. It makes very little difference to
>any 'ranking'.
>
>I would suggest then;  that the AW paper is an "acedemic paper" and the BQH
>method represents years and years of hard work (helped and verified by
>many) that offers a practical tool rather than a theoretical proposal.
>
>If , after more work, we see the result of the AW proposal really does
>offer a better tool then I'm all for that.
>
>Graham F5VHX, G8MBI
>
>
>
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