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Old May 13th 10, 12:41 AM posted to rec.radio.amateur.antenna
lu6etj lu6etj is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 143
Default Feeding System found it = Mosley

On 12 mayo, 19:00, Owen Duffy wrote:
I read on their web page for some more BS.

In explaining why their traps are lossless:

"Gain is a function of element spacing and boom length and not what
constitutes an element. *The published gain figures for our products are
dBd, actual measured gain. *Antennas which use other forms of trapping such
as linear loading, poor trap copies, baluns or matching devices have
inherit loss. "

So, all these things have inherent loss, but not their traps.

Fact is that GAIN is reduced by LOSS, anywhere and everywhere in the
system, dB for dB. This includes conductor losses, dielectric losses, and
trap losses which they exclude from their definition.

Owen


As I said: "I wanted to discover what was the supporting idea behind
that
feeding system for its designers"

Defend commercial stuff and his claims It is not my job (I do not
trust enough in all of them), I am an Amateur :) but seems to me that
their concept it is not opposed to my modest theoretical knowledge
neither my simulations exercises in 4NEC2 (their "numbers" partially
agree with mine, although I have not simulated exactly a Mosley
antenna model).
Now I am only interested in validate or negate the especific technical
concept and explanation given, from a scientific perspective.

Proposition =. Is it possible match the impedance of some Yagi
antennas lengthening the driven element and canceling its inductive
reactance splitting the element and adding series caps?
Can be made these caps with special pieces of insulated wire
introduced in element tube?.

Try it... lenghten in a NEC simulation the driven element and cancel
inductive reactance = impedance raises and gain stays (I used
"3YAGI20.NEC" from 4NEC2 examples provided with Arie soft, for
testing).
In my test, raisen length from 5.12 m to 5.85 m per leg, Zin raises
from 31.8 + j2 ohm to 50.9 + j150 ohm and gain stays in 12 dBi (with a
fast ground and 15 m height).

73

Miguel Ghezzi LU6ETJ