Hi Marshall,
At 06:36 PM 3/28/97 +0000, you wrote:
>Hi, Bob--
>
>>>baluns. IMHO, however, some of these circuits are much
>more efficient than using a separate balun to force
>balance into an inherently unbalanced circuit. <<
>
>VERY true. Commercial baluns have to be a compromise, and some of
>them are not a very good one at that! I've never seen any figures on
>the subject but I suspect that the broader the frequency "bandwidth"
>of a balun, the lossier it is.
Frank Witt, AI1H, has a pretty good article on this subject in the Antenna
Compendium V. He says that as you move away from the design impedance and
frequency of the balun, losses increase dramatically.
-- But, it is more dependent on impedance than frequency. (at least,
that's the way I interpret it) In other words, if the balun design
impedance is 50 ohms and it sees 50 ohms, it may handle a broad frequency
range efficiently. But, if it sees some other impedance, losses increase,
especially if the frequency is far from the design frequency.
Of course, when we are trying to use a multiband antenna with a tuner,
that's exactly what happens. As we move away from the antenna's resonant
frequencies, we move away from 50 ohms (or what ever it was designed for)
and balun losses increase.
At this point, I know more about this subject than I understand!!
Thanks for your comments.
CUL,
Bob Kellogg, AE4IC, Greensboro, NC
Prolably, but not nececelery. - Benny Hill
WIMPS: Qs=000 30m=0 17m=0 12m=0 States=00/00/00
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