At 18:11 2004-07-14 , you wrote:
>The worse thing about any debate is all the bad data that
>pours out of well-intentioned but totally meaningless
>efforts to prove or disprove points.
Tom, if I say that the test were made at 432 MHz and they were pretty
conclusive, they were. On 432 MHz !
If relevant to HF is another matter, and therefore I stated nothing but 432
MHz, clearly remembering the F/B discussion we had a couple of weeks ago..
The reason for picking up on the subject was because there was a discussion
on pattern distorsion of yagis when not using a balun, and in my opinion
there was room for data proving the opposite, be it at 432 MHz, we are
still talking yagis.
>> The tests were pretty conclusive, there was not much
>pattern distorsion at
>> all without the balun. The measurements were made at the
>official German
>> PTT antenna range, so we can indeed trust the integrity of
>the plots. I
>> have seen copies and the pattern distorsion was indeed
>minimal.
>
>"Official" is nearly meaningless in the context of "valid".
>People make invalid measurements all the time, even when
>they use the correct equipment.
>I watched the HP sale representative do a demo at a radio
>club that was an absolutely improper use of the analyzer
>because he did not understand the problem he was measuring.
>He understood the results. He understood the source. He
>didn't understand the variables.
The lousy HP sale representative has nothing to do with this issue, yes he
was lousy.
The mere fact that the antenna measurements were valid and carried out by
people with excellent knowledge was just information added so that we would
not end up in an endless discussion regarding wether the test range was a
"proper" antenna range or not.
>We never could test one antenna especially at a greatly
>different frequency and say with any accuracy "you never
>need a balun" unless we fully understood how to obtain the
>worse case and best case for antennas.
Various different antennas were tested over a wide range of frequencies,
same result.
But I suppose this is of no importance, as the test were meaningless.. :-)
>I can say from direct experience that Yagi patterns can be
>severely compromised with improper feed isolation.
I have no problem with this statement, but _I_ have direct experience of
quite the opposite, in many different designs, some of which I use every day.
73/Peter SM2CEW
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|