Owen Duffy wrote:
Owen Duffy wrote in
:

Ok, since you are discussing impedance matching, what was the effect on
VSWR bandwidth.

It seems to me that as you go lower in frequency, the inductive reactance
at the feedpoint becomes less and the series stub reactance becomes
greater, so one aggravates the other.

The question is whether the outcome is narrower than desired or available
with other matches.

Because Mosely's explanation contains so much BS, I have no faith in
anything they have said.



Aside from marketing BS..

Owen raises a good point. You bring the feedpoint Z from 31.8+j2 to
51+j150. Resonating the j150 with a -j150 is fine, but now,you've
effectively got a resonant circuit with moderately high Q, or, at the
very least, more circulating power between matching network and antenna.

On 12 mayo, 22:12, Jim Lux wrote:
Owen Duffy wrote:
Owen Duffy wrote in
:

Ok, since you are discussing impedance matching, what was the effect on
VSWR bandwidth.

It seems to me that as you go lower in frequency, the inductive reactance
at the feedpoint becomes less and the series stub reactance becomes
greater, so one aggravates the other.

The question is whether the outcome is narrower than desired or available
with other matches.

Because Mosely's explanation contains so much BS, I have no faith in
anything they have said.

Aside from marketing BS..

Owen raises a good point. *You bring the feedpoint Z from 31.8+j2 to
51+j150. *Resonating the j150 with a -j150 is fine, but now,you've
effectively got a resonant circuit with moderately high Q, or, at the
very least, more circulating power between matching network and antenna.- Ocultar texto de la cita -

- Mostrar texto de la cita -

Very good and detailed análisis Jim.

Owen point it is also good, but seems to me it is a little odd biased
by the others claims of Mosley people :)
I think that if Owen "forget Mosley" perhaps he could give another
chance to the system itself. For example = not all directive antennas
needs a great bandwidth...

However 4NEC2 simulation seem to favor the system we are analyzing.
Adding an ideal reactance of -155 ohms coarsely in the first segment
to the right of the central segment of mentioned provided 4NEC2 model
with lengthen driven element and doing a 13 to15 MHz frequency sweep I
got a lightly increment on VSWR bandwidth of approximately 200 kHz and
a decreasing of VSWR at resonance from aprox 1.5:1 to 1:1 (perhaps for
the localization of capacitive reactance on model?).

Finally, maybe I am also a little biased because my third speculation
was viable and that made me feel happy, hi hi :D

73

Miguel Ghezzi LU6ETJ

lu6etj wrote in news:e57e2fbf-75a6-4014-a190-
:

Adding an ideal reactance of -155 ohms

Bit is not a fixed reactance, it is a transmission line element, and you
should model it as that, even if lossless.

Owen

On 13 mayo, 02:11, Owen Duffy wrote:
lu6etj wrote in news:e57e2fbf-75a6-4014-a190-
:

Adding an ideal reactance of -155 ohms

Bit is not a fixed reactance, it is a transmission line element, and you
should model it as that, even if lossless.

Owen

;=D Easy and quick 50 ohm transmission line 0.05121 lambda (-150
ohms) replacement for old fix reactance in the same segment = ¡Same
result...! and now... I'm go to ZZZZZ

73

Miguel

lu6etj wrote in news:90c5c494-45a0-476c-8f9e-
:

On 13 mayo, 02:11, Owen Duffy wrote:
lu6etj wrote in news:e57e2fbf-75a6-4014-a190-
:

Adding an ideal reactance of -155 ohms

Bit is not a fixed reactance, it is a transmission line element, and
you
should model it as that, even if lossless.

Owen

;=D Easy and quick 50 ohm transmission line 0.05121 lambda (-150
ohms) replacement for old fix reactance in the same segment = ¡Same
result...! and now... I'm go to ZZZZZ

If you specified it in wavelengths, wouldn't that have a constant
reactance.

The real stub is a fixed physical length, and its reactance changes with
frequency.

Owen

On 13 mayo, 04:59, Owen Duffy wrote:
lu6etj wrote in news:90c5c494-45a0-476c-8f9e-
:





On 13 mayo, 02:11, Owen Duffy wrote:
lu6etj wrote in news:e57e2fbf-75a6-4014-a190-
:

Adding an ideal reactance of -155 ohms

Bit is not a fixed reactance, it is a transmission line element, and
you
should model it as that, even if lossless.

Owen

;=D *Easy and quick 50 ohm transmission line 0.05121 lambda *(-150
ohms) replacement for old fix reactance in the same segment = ¡Same
result...! *and now... I'm go to ZZZZZ

If you specified it in wavelengths, wouldn't that have a constant
reactance.

The real stub is a fixed physical length, and its reactance changes with
frequency.

Owen- Ocultar texto de la cita -

- Mostrar texto de la cita -

Good morning (here) Mr. Duffy

It was in meters...

Please, remember the proposition to validate or refute. Once validated
(if it is), then we could think about details

You know, I was not trying to find out if it is the best matching
method but whether it is a viable method. For example: In precedent
post I said I was using a "coarsely" reactance for a basic hypothesis
test because my dictionary suggest that word, perhaps I should have
written: rudely? approximately?

SRI, this is not my natural language and I may not adequately
explained my goal...

Miguel Ghezzi LU6ETJ

On Thu, 13 May 2010 05:11:58 -0700 (PDT), lu6etj
wrote:

I was using a "coarsely" reactance for a basic hypothesis
test because my dictionary suggest that word, perhaps I should have
written: rudely? approximately?

Hi Miguel,

Coarse,
Rude,
Approximate
are the correct forms as adjectives that describe things.

Coarsely,
Rudely,
Approximately
are forms of adverbs that describe actions.

Any of the six words are easily understood in context.

I understand your goal. Newsgroup behavior is about speaking more
completely to the larger audience. Thus, other's will add commentary
to your goal.

73's
Richard Clark, KB7QHC

Owen Duffy wrote:
lu6etj wrote in news:e57e2fbf-75a6-4014-a190-
:

Adding an ideal reactance of -155 ohms

Bit is not a fixed reactance, it is a transmission line element, and you
should model it as that, even if lossless.

Owen
In the Mosley case, judging from the writeup at the link supplied a few
days ago, the series capacitor is sufficiently short (a few inches?),
that it's probably safe to consider it a lumped element. Isn't it just a
wire in the middle of a tube.. essentially a coaxial capacitor.

On 13 mayo, 15:38, Jim Lux wrote:
Owen Duffy wrote:
lu6etj wrote in news:e57e2fbf-75a6-4014-a190-
:

Adding an ideal reactance of -155 ohms

Bit is not a fixed reactance, it is a transmission line element, and you
should model it as that, even if lossless.

Owen

In the Mosley case, judging from the writeup at the link supplied a few
days ago, the series capacitor is sufficiently short (a few inches?),
that it's probably safe to consider it a lumped element. Isn't it just a
wire in the middle of a tube.. essentially a coaxial capacitor.

True. Since delta f is small (aprox 2%), considering it a plain
condenser, reactance variation between 14 and 14.3 MHz is from 150 to
146.6 ohm; considering it a transmission line variation is from 150 to
146.8 -worthless-
In the worst case, thinking it as a coaxial condenser could have a
higher error on cable length calculation more than in the reactancev
variation with frequency.