On 4 Jun 2004 10:44:01 -0700, (Art Unwin KB9MZ)
wrote:
"According to current
theory, you have to give up one of the three-size, efficiency, or
bandwidth-to achieve any one of the other two."

snip
Is the above statement correct ?

Hi Art,

In a crude and shorthand way, yes. This is why your small 160M
vertical dipole is up to 15 to 17dB below performance in comparison to
a full size one. All common legacy for CFAs, EHs, fractals, and the
rest of this ilk that come down the pike.

73's
Richard Clark, KB7QHC

That says that narrow bandwidth contributes to higher efficiency
which is how I always understood it.(Though many do not accept that)
But as you say it is a shorthand type statement.
My antenna on 160 is very narrow banded at any particular setting or
frequency
( two loops and a short dipole coupled in tight cluster form),when
modelled ,shows part of the current curve breaking out into a sino
soidal oscillation (no phase change) for portions of the antenna.
Such modelling, ofcourse, requires a large amount of points per unit
length for high accuracy and the occillation would probably not show
up visually if calculation points were reduced.
It does not seem to affect things in practice on the air but I have
often wondered what the consequences would be if the bandwidth was
narrowed even more and the current oscillation possibly propagate over
all the of the antenna !
With the current taking on an occillation it would suggest changes in
radiation

Art



Richard Clark wrote in message . ..
On 4 Jun 2004 10:44:01 -0700, (Art Unwin KB9MZ)
wrote:
"According to current
theory, you have to give up one of the three-size, efficiency, or
bandwidth-to achieve any one of the other two."

snip
Is the above statement correct ?

Hi Art,

In a crude and shorthand way, yes. This is why your small 160M
vertical dipole is up to 15 to 17dB below performance in comparison to
a full size one. All common legacy for CFAs, EHs, fractals, and the
rest of this ilk that come down the pike.

73's
Richard Clark, KB7QHC

On 5 Jun 2004 19:02:56 -0700, (Art Unwin KB9MZ)
wrote:

That says that narrow bandwidth contributes to higher efficiency
which is how I always understood it.(Though many do not accept that)

Hi Art,

When a low bandwidth antenna has very high efficiency (in the range of
95-98 percent), "more" efficient is not very remarkable.

The problem you are encountering is trying to equate bandwidth/Q with
efficiency. There is an old adage: correlation is not causation. A
successful antenna design is by definition lossy = radiation
resistance. You can reduce this loss to zero, boost the Q, make for a
very small bandwidth and come up with a very inefficient antenna.
Same thing goes for Tube finals' tuning. You don't want narrow
bandwidth/high Q because that means no power will leave the
transmitter. Q for the Finals falls between 10 and 15 because the
load must be a loss.

The coil/capacitor that makes up the finals tuning has an "unloaded" Q
that is high, which means that the coil/capacitor in and of itself
does not contribute to the loss, but as a system, Q is relatively low
(by at least a power of 10 if not 20). It would be impossible to
measure the unloaded Q of an antenna because it is necessarily MUCH
larger than a conventional coil/capacitor lumped circuit. Being large
means that it encompasses that loss of radiation resistance.

There is, of course, a hazy area where antennas get very small, or
finals get very big. The 1M loops sold as "magnetic" loops certainly
approach that, and yet the ratio of radiation resistance and loss
resistance in the low bands is clearly a loser proportion for this
breed. If you have no choice, even 5% efficiency is gold bond stuff.
However, simply because it has high Q does not elevate its poor
performance.

This returns us to that crude triad of pick any two characteristics
and leave the third for the vultures.

73's
Richard Clark, KB7QHC

73's
Richard Clark, KB7QHC

snip
wrote:
"According to current
theory, you have to give up one of the three-size, efficiency, or
bandwidth-to achieve any one of the other two."

snip
Is the above statement correct ?

Hi Art,

In a crude and shorthand way, yes. This is why your small 160M
vertical dipole is up to 15 to 17dB below performance in comparison to
a full size one. All common legacy for CFAs, EHs, fractals, and the
rest of this ilk that come down the pike.

73's
Richard Clark, KB7QHC

Hmm I don't know where you are coming from but I ouldn't put my
antenna
in the CFA group that you state above. I know in the past that your
antenna is better than mine which is O.K. but the fact is that many
amateurs like to experiment and also pursue the "holy grail" Each
attempt provide knowledge
which is why antennas are pursued so much .I wager that the patent
pending
aproach discussed will provide welcome reading for everybody on this
newsgroup.
As for my particular antenna pursuit I am still not ready to throw it
into the dustbin as every change provides new insights on antennas (
the sinosoidal current wave for one)
I use my present antenna in the rotatable form on the top of the tower
for convenience but I modelled it after reading your comments and they
are as follows

Top band....vertical orientation
Impedance 349 +j41 ohms ( 186-j13 ohms when horizontally oriented
on the tower)
Load losses 2.88 db
Efficiency 51.5%
Radiation peak 23 degrees elevation -1.53dbi

The above has bandwidth of around 5 Khz which is O.K. for audio,
and frequency of use is selectable across the band.
Since the feed point is at the center I don't have to tear up the lawn
for those rotten radial wires.
Efficiency jumps to over 90% on 80 meters and other bands with the
typical figure eight form pattern, but my primary pursuit is on top
band.
Yes, the antenna can be beaten when following conventional design but
the hunt
using unconventional designs is part of the excitement, where slight
change of inductance value moves you along the band /bands with out
restriction with respect to power , the requirement of high voltage
capacitors or large areas of grounding systems.
My antenna may be regarded as 'useless' by many but, unlike the CFA
and other antennas you placed me with, my antenna is in use and the
impedances provided seem to match those given by modelling using a PRO
antenna program and using maximum segments because of the
UNCONVENTIONAL close coupled cluster design.
Unconventional design provides insights to antennas like the
oscillations that I refered to earlier, which is not to be seen on
conventional designs and for which I seek further understanding and
explanation.
The new unconventional design from R.I. which is 'patent pending' no
less may well provide further insights that we are unaware of.
Unfortunately his efforts WILL be ridiculed by those who know that
'every thing about antennas is known' and by sharing he has shown his
personal foolishnes to his peers.
When will the amateur learn that it is a waste of time to experiment
where the failures are heralded and the minutia of new facts are
ignored ???
Please forgive me for writing this extra post which has strayed from
my original post.
Regards to all
Art

On 6 Jun 2004 17:11:50 -0700, (Art Unwin KB9MZ)
wrote:

Top band....vertical orientation Impedance 349 +j41 ohms
( 186-j13 ohms when horizontally oriented on the tower)

This reveals the tower is a significant radiator and a necessary
adjunct for the operation of the antenna. This is an identical
characteristic of CFA's, EH's and fractals.

Unconventional design provides insights to antennas like the
oscillations that I refered to earlier, which is not to be seen on
conventional designs and for which I seek further understanding and
explanation.

I see nothing unconventional at all.

73's
Richard Clark, KB7QHC

I duly note your judgement which appears to be based on the feed impedances
provided. For the record the vertical was modelled
with one end about two feet above the ground (over perfect ground) whereas
the horizontal form was modelled at 820 inches above ground , again over
"perfect ground". I look forward to when the initial 'new' technology
alluded to in this thread is available for full discusion.
Regards to all
Art


"Richard Clark" wrote in message
...
On 6 Jun 2004 17:11:50 -0700, (Art Unwin KB9MZ)
wrote:

Top band....vertical orientation Impedance 349 +j41 ohms
( 186-j13 ohms when horizontally oriented on the tower)

This reveals the tower is a significant radiator and a necessary
adjunct for the operation of the antenna. This is an identical
characteristic of CFA's, EH's and fractals.

Unconventional design provides insights to antennas like the
oscillations that I refered to earlier, which is not to be seen on
conventional designs and for which I seek further understanding and
explanation.

I see nothing unconventional at all.

73's
Richard Clark, KB7QHC

snip
wrote:
"According to current
theory, you have to give up one of the three-size, efficiency, or
bandwidth-to achieve any one of the other two."

snip
Is the above statement correct ?

Hi Art,

In a crude and shorthand way, yes. This is why your small 160M
vertical dipole is up to 15 to 17dB below performance in comparison to
a full size one. All common legacy for CFAs, EHs, fractals, and the
rest of this ilk that come down the pike.

73's
Richard Clark, KB7QHC

Hmm I don't know where you are coming from but I ouldn't put my
antenna
in the CFA group that you state above. I know in the past that your
antenna is better than mine which is O.K. but the fact is that many
amateurs like to experiment and also pursue the "holy grail" Each
attempt provide knowledge
which is why antennas are pursued so much .I wager that the patent
pending
aproach discussed will provide welcome reading for everybody on this
newsgroup.
As for my particular antenna pursuit I am still not ready to throw it
into the dustbin as every change provides new insights on antennas (
the sinosoidal current wave for one)
I use my present antenna in the rotatable form on the top of the tower
for convenience but I modelled it after reading your comments and they
are as follows

Top band....vertical orientation
Impedance 349 +j41 ohms ( 186-j13 ohms when horizontally oriented
on the tower)
Load losses 2.88 db
Efficiency 51.5%
Radiation peak 23 degrees elevation -1.53dbi

The above has bandwidth of around 5 Khz which is O.K. for audio,
and frequency of use is selectable across the band.
Since the feed point is at the center I don't have to tear up the lawn
for those rotten radial wires.
Efficiency jumps to over 90% on 80 meters and other bands with the
typical figure eight form pattern, but my primary pursuit is on top
band.
Yes, the antenna can be beaten when following conventional design but
the hunt
using unconventional designs is part of the excitement, where slight
change of inductance value moves you along the band /bands with out
restriction with respect to power , the requirement of high voltage
capacitors or large areas of grounding systems.
My antenna may be regarded as 'useless' by many but, unlike the CFA
and other antennas you placed me with, my antenna is in use and the
impedances provided seem to match those given by modelling using a PRO
antenna program and using maximum segments because of the
UNCONVENTIONAL close coupled cluster design.
Unconventional design provides insights to antennas like the
oscillations that I refered to earlier, which is not to be seen on
conventional designs and for which I seek further understanding and
explanation.
The new unconventional design from R.I. which is 'patent pending' no
less may well provide further insights that we are unaware of.
Unfortunately his efforts WILL be ridiculed by those who know that
'every thing about antennas is known' and by sharing he has shown his
personal foolishnes to his peers.
When will the amateur learn that it is a waste of time to experiment
where the failures are heralded and the minutia of new facts are
ignored ???
Please forgive me for writing this extra post which has strayed from
my original post.
Regards to all
Art