Q. What is the optimum antenna type to give the maximum gain given a
fixed overall length of elements? Or, alternately, what's the minimum
amount of wire/tubing to give a specified gain? (Neglecting support
structures)
As an example, for a gain of 15 dBi, an 11 element Yagi appears to have
about the same gain as two stacked 6 element Yagis which collectively
use one more element. But what about collinears, V Beams, arrays of
different sized Yagis etc. etc.?
Just out of curiosity.

Alan

a parabolic reflector fed with a feedhorn. no 'elements', just a hole in a
pipe and a big curved plate. you need to define the parameters a bit more.
for instance with no reflectors or directors, just driven verticals you can
make lots of gain. phased array radars have no wire/tubing elements, just
holes in a plate each with its own transmitter/receiver. and how do you
count dishes, corner reflectors, and the ground? by changing the height of
an antenna you can drastically change the gain at some particular takeoff
angle, so maybe you want to restrict it to free space. an do you want
minimum element count, or total material length? a very long wire can
create high gain lobes, but may not be very useful if you are thinking of
something rotateable.

"Alan Peake" wrote in message
...
Q. What is the optimum antenna type to give the maximum gain given a fixed
overall length of elements? Or, alternately, what's the minimum amount of
wire/tubing to give a specified gain? (Neglecting support structures)
As an example, for a gain of 15 dBi, an 11 element Yagi appears to have
about the same gain as two stacked 6 element Yagis which collectively use
one more element. But what about collinears, V Beams, arrays of different
sized Yagis etc. etc.?
Just out of curiosity.

Alan

Dave wrote:
a parabolic reflector fed with a feedhorn. no 'elements', just a
hole in a pipe and a big curved plate. you need to define the
parameters a bit more.

OK, maximum gain for a single frequency, free space, sidelobes and
back-front ratio not important. Not concerned about number of elements -
only minimum total material length. Doesn't need to be rotatable - this
is a purely theoretical exercise.

Parabolic reflector sounds good but it's a bit hard to quantify for the
purposes of minimising total material length. Perhaps one could use a
wire mesh dish. Would that use more or less material than a Yagi? I
would imagine that a phased array radar could use the wire mesh approach
but the same questions would apply as for the parabolic reflector. Same
for corner reflectors.
Arrays of driven elements may be promising but the few such antennae
that I've simulated so far, use more material than Yagis for the same gain.

Alan

"Alan Peake" wrote in message
...


Dave wrote:
a parabolic reflector fed with a feedhorn. no 'elements', just a
hole in a pipe and a big curved plate. you need to define the
parameters a bit more.

OK, maximum gain for a single frequency, free space, sidelobes and
back-front ratio not important. Not concerned about number of elements -
only minimum total material length. Doesn't need to be rotatable - this is
a purely theoretical exercise.

Parabolic reflector sounds good but it's a bit hard to quantify for the
purposes of minimising total material length. Perhaps one could use a
wire mesh dish. Would that use more or less material than a Yagi? I
would imagine that a phased array radar could use the wire mesh approach
but the same questions would apply as for the parabolic reflector. Same
for corner reflectors.
Arrays of driven elements may be promising but the few such antennae
that I've simulated so far, use more material than Yagis for the same
gain.

Alan


length is not a property of 'material'. mass, volume, their ratio, density,
conductivity, color, hardness, etc, are properties that can be measured.
'theoretically' the best antenna is a conductor from the source to the
receiver. a parabolic reflector can have area and thickness, therefore
volume, but the area is variable depending on how thick or thin you can make
it. any wire can be made into a parabolic reflector by smashing it thin
enough, witness the reflectors used on deep space satellites that are
extremely thin and light. or the metallic coating of a telescope mirror
that may be only a few atoms thick and yet yields tremendous gain. phased
arrays for radar get better as you remove more material from the surface
they are built from, the more holes, the better the pattern can be... so
less is more. arrays of driven elements, like the lpda, while looking
impressive and using lots of material, perform poorly at a single frequency,
but have the advantage of performing equally poorly over a wide range of
frequencies. designing antennas is a game of tradeoffs.... bandwidth for
gain, size for efficiency, gain for size, add in weight or some other
constraint like diameter and length of tubing, or dollars worth of
materials, and you add a whole new dimension. and then you need
'practicality'. as our friend art has found, you can feed parameters into
an optimizer program and let it run wild and get a supergain antenna that
fits in a shoebox, but try to build it and you get an air cooled dummy
load... or something that only induces currents on the support structure or
feedline.

the first step of engineering an antenna is to constrain the design with
practical measures... frequency range, size, weight, wind load area, cost.
then research possible alternative designs. then tweak the possible designs
carefully to see if they can be adjusted for your specific use. but be very
careful, if you suddenly find the tweaked design providing much larger gains
or varying greatly from the starting point, back up and see what has
happened... something is wrong. the most common problem is that someone
takes a standard yagi and puts it into an optimizer and sets it for 'max
gain' at one frequency, with no other constraints. the optimizer chugs
along and the gain goes up, and up, and up, and up!!! but when you look at
the results there are several elements bunched around the driven element and
the feedpoint impedance has gone down to a fraction of an ohm. don't apply
for a patent like art, throw it out and start over with more reasonable
constraints. give it a range of frequencies, constrain the feedpoint
impedance to a useful range, limit the element spacing, the total boom
length, etc, until it gives you something slightly tweaked for your specific
application but not off in left field.

On 1 jul, 14:36, Alan Peake wrote:
Q. What is the optimum antenna type to give the maximum gain given a
fixed overall length of elements? Or, alternately, what's the minimum
amount of wire/tubing to give a specified gain? (Neglecting support
structures)
As an example, for a gain of 15 dBi, an 11 element Yagi appears to have
about the same gain as two stacked 6 element Yagis which collectively
use one more element. But what about collinears, V Beams, arrays of
different sized Yagis etc. etc.?
Just out of curiosity.

Alan

Hello Alan,

There is no optimum antenna design that fits everything. Some factors:
Center Frequency
Side lobe level requirements
Gain requirements
Available materials
Required bandwidth.
Design skills / Experience
Ease of production
Number of antennas to be produced,
Available volume
Sentimental
Environmental aspects
Visibility (think of covert antennas).

There are (physical) limitations on antenna gain and antenna size.
Antennas with high gain must have a size far above wavelength.
Reduction of side lobes with given gain also requires a larger
antenna.

Omni directional gain requires large vertical antenna structures.
Every 3 dB gain increase, requires double the (vertical) size.

Best regards,

Wim
PA3DJS
www.tetech.nl
don't forget to remove abc when replying directly.

On Jul 1, 11:05 am, Wimpie wrote:
On 1 jul, 14:36, Alan Peake wrote:

Q. What is the optimum antenna type to give the maximum gain given a
fixed overall length of elements? Or, alternately, what's the minimum
amount of wire/tubing to give a specified gain? (Neglecting support
structures)
As an example, for a gain of 15 dBi, an 11 element Yagi appears to have
about the same gain as two stacked 6 element Yagis which collectively
use one more element. But what about collinears, V Beams, arrays of
different sized Yagis etc. etc.?
Just out of curiosity.

Alan

Hello Alan,

There is no optimum antenna design that fits everything. Some factors:
Center Frequency
Side lobe level requirements
Gain requirements
Available materials
Required bandwidth.
Design skills / Experience
Ease of production
Number of antennas to be produced,
Available volume
Sentimental
Environmental aspects
Visibility (think of covert antennas).

There are (physical) limitations on antenna gain and antenna size.
Antennas with high gain must have a size far above wavelength.
Reduction of side lobes with given gain also requires a larger
antenna.

Omni directional gain requires large vertical antenna structures.
Every 3 dB gain increase, requires double the (vertical) size.

Best regards,

Wim
PA3DJSwww.tetech.nl
don't forget to remove abc when replying directly.

May I offer a rebuttal to your use of "size:" with respect to
radiators?
The addition of radiators and a time varying field to a Gaussian field
shows that a radiator can be any size,shape or elevation as long as it
is in equilibrium.
This is because the result of additions to Gauss's static law results
in the same law of Maxwell.
It can also be seen that any deviation from a straight line format
which creats lumped loading must be neutralized since
radiation is related to distributed loads L and C. Thus shape or size
is a determination of the neutralisation of lumped loads
while attaining equilibrium. With the above in hand it can be seen
that Foucault current generates a field that elevates particles that
have attained a weak magnetic field by entering the earths system
which provides for their rejection or ejection. Per Newtons Law the
weak forces
involved (Fermi) create an oscillation of the radiator which is a
mirror image of arriving impulses upon a radiuator with the same
natural resonance.
It is only convention that calls for an radiator to be straight of
which a helix antenna is an excellent example ,where a continuation of
rotation back to the originating point provides for a full circuit in
equilibrium si9nce added lumped loads are cancelled. Examples of the
foucault current was provided earlier on this forum when describing
the separation of scrap metal by Foucault current rejection. As with
Newton, Faraday Gauss etc all laws depend on the theme of equilibrium
within a boundary of a balanced universe and not on minute sections
thereof.
Have a great week end
Art

Art Unwin wrote:

...
May I offer a rebuttal to your use of "size:" with respect to
radiators?
The addition of radiators and a time varying field to a Gaussian field
shows that a radiator can be any size,shape or elevation as long as it
is in equilibrium.
This is because the result of additions to Gauss's static law results
in the same law of Maxwell.
It can also be seen that any deviation from a straight line format
which creats lumped loading must be neutralized since
radiation is related to distributed loads L and C. Thus shape or size
is a determination of the neutralisation of lumped loads
while attaining equilibrium. With the above in hand it can be seen
that Foucault current generates a field that elevates particles that
have attained a weak magnetic field by entering the earths system
which provides for their rejection or ejection. Per Newtons Law the
weak forces
involved (Fermi) create an oscillation of the radiator which is a
mirror image of arriving impulses upon a radiuator with the same
natural resonance.
It is only convention that calls for an radiator to be straight of
which a helix antenna is an excellent example ,where a continuation of
rotation back to the originating point provides for a full circuit in
equilibrium si9nce added lumped loads are cancelled. Examples of the
foucault current was provided earlier on this forum when describing
the separation of scrap metal by Foucault current rejection. As with
Newton, Faraday Gauss etc all laws depend on the theme of equilibrium
within a boundary of a balanced universe and not on minute sections
thereof.
Have a great week end
Art

Art:

This mysterious "equilibrium" (which I seem to have a bit of problem
getting my mind wrapped about), although you, seemingly, sum up a group
of properties with a single word, isn't this just "resonance"--with
respect to conductor length/width, capacitance to surrounding objects
and the shape/form of the magnetic field produced by antenna currents, etc?

However, a thought did come to my mind ... with the new technique of
"taking pictures" of light waves/particles--if a super-strong
electromagnet was pulsed in an enclosure of excitable gas(es), perhaps
we could see some unknown/yet-unseen phenomenon ...

However, you are speaking of resonance, aren't you? still-scratching-head

Regards,
JS

"John Smith" wrote in message
...
Art Unwin wrote:

...
May I offer a rebuttal to your use of "size:" with respect to
radiators?
The addition of radiators and a time varying field to a Gaussian field
shows that a radiator can be any size,shape or elevation as long as it
is in equilibrium.
This is because the result of additions to Gauss's static law results
in the same law of Maxwell.
It can also be seen that any deviation from a straight line format
which creats lumped loading must be neutralized since
radiation is related to distributed loads L and C. Thus shape or size
is a determination of the neutralisation of lumped loads
while attaining equilibrium. With the above in hand it can be seen
that Foucault current generates a field that elevates particles that
have attained a weak magnetic field by entering the earths system
which provides for their rejection or ejection. Per Newtons Law the
weak forces
involved (Fermi) create an oscillation of the radiator which is a
mirror image of arriving impulses upon a radiuator with the same
natural resonance.
It is only convention that calls for an radiator to be straight of
which a helix antenna is an excellent example ,where a continuation of
rotation back to the originating point provides for a full circuit in
equilibrium si9nce added lumped loads are cancelled. Examples of the
foucault current was provided earlier on this forum when describing
the separation of scrap metal by Foucault current rejection. As with
Newton, Faraday Gauss etc all laws depend on the theme of equilibrium
within a boundary of a balanced universe and not on minute sections
thereof.
Have a great week end
Art

Art:

This mysterious "equilibrium" (which I seem to have a bit of problem
getting my mind wrapped about), although you, seemingly, sum up a group of
properties with a single word, isn't this just "resonance"--with respect
to conductor length/width, capacitance to surrounding objects and the
shape/form of the magnetic field produced by antenna currents, etc?

However, a thought did come to my mind ... with the new technique of
"taking pictures" of light waves/particles--if a super-strong
electromagnet was pulsed in an enclosure of excitable gas(es), perhaps we
could see some unknown/yet-unseen phenomenon ...

However, you are speaking of resonance, aren't you?
still-scratching-head

Regards,
JS

no, he's not... its the cosmic equilibrium between his fictitious particles
and the attraction of them the diamagnetic materials that makes antennas
work... of course he can't explain why ferromagnetic materials also work as
antennas, but that hasn't stopped him from spewing his garbage all over this
group. if you keep scratching your head while you try to figure out what he
is talking about you will run out of hair before you even get to first base.

Dave wrote:

...
no, he's not... its the cosmic equilibrium between his fictitious particles
and the attraction of them the diamagnetic materials that makes antennas
work... of course he can't explain why ferromagnetic materials also work as
antennas, but that hasn't stopped him from spewing his garbage all over this
group. if you keep scratching your head while you try to figure out what he
is talking about you will run out of hair before you even get to first base.



Actually, there is only one alternative--the ether ... something which I
wish they will explore with new techniques ... Something (ether) which
even Einstein acknowledged. However, why Art would "waltz" around
something which is already being explored/argued, and cloak that
"waltzing" in an unfamiliar term(s) is simply beyond me ... unless ones'
point is obsfucation.

Regards,
JS

On Jul 1, 1:58 pm, John Smith wrote:
Art Unwin wrote:
...
May I offer a rebuttal to your use of "size:" with respect to
radiators?
The addition of radiators and a time varying field to a Gaussian field
shows that a radiator can be any size,shape or elevation as long as it
is in equilibrium.
This is because the result of additions to Gauss's static law results
in the same law of Maxwell.
It can also be seen that any deviation from a straight line format
which creats lumped loading must be neutralized since
radiation is related to distributed loads L and C. Thus shape or size
is a determination of the neutralisation of lumped loads
while attaining equilibrium. With the above in hand it can be seen
that Foucault current generates a field that elevates particles that
have attained a weak magnetic field by entering the earths system
which provides for their rejection or ejection. Per Newtons Law the
weak forces
involved (Fermi) create an oscillation of the radiator which is a
mirror image of arriving impulses upon a radiuator with the same
natural resonance.
It is only convention that calls for an radiator to be straight of
which a helix antenna is an excellent example ,where a continuation of
rotation back to the originating point provides for a full circuit in
equilibrium si9nce added lumped loads are cancelled. Examples of the
foucault current was provided earlier on this forum when describing
the separation of scrap metal by Foucault current rejection. As with
Newton, Faraday Gauss etc all laws depend on the theme of equilibrium
within a boundary of a balanced universe and not on minute sections
thereof.
Have a great week end
Art

Art:

This mysterious "equilibrium" (which I seem to have a bit of problem
getting my mind wrapped about), although you, seemingly, sum up a group
of properties with a single word, isn't this just "resonance"--with
respect to conductor length/width, capacitance to surrounding objects
and the shape/form of the magnetic field produced by antenna currents, etc?

However, a thought did come to my mind ... with the new technique of
"taking pictures" of light waves/particles--if a super-strong
electromagnet was pulsed in an enclosure of excitable gas(es), perhaps
we could see some unknown/yet-unseen phenomenon ...

However, you are speaking of resonance, aren't you? still-scratching-head

Regards,
JS

No. Resonance is a quality of equilibrium but equilibrium is not
necessarily a part of resonance.
For instance, a full wavelength corresponding to a period of
oscillation is a form in equilibrium
where as a fractional wavelength can be resonant but certainly in
equilibrium
This really ia at the bottom of Newtons law regarding action and
reaction where all forces around a point
must equal zero. For instance if we have a member that is carrying an
alternating current applying such law states that there is
no moving charge on the inside of the member and where all charges on
the surface are in static form. The same law is used to determine the
likes oif skin depth.Now I have a problem with fractional WL current
carrying members where the surface charges move to one end which
suggests a internally moving charge. This effect can be seen when
comparing a dipole with a quad where the dipole can create corona at
the ends as the charges pile up as they look for a place to go doing
the time space of one period
where as a quad is a full WL anmd in equilibrium.
Maxwells law is based on equilibrium which means it can accoun t for
what is known as the "week force" which Einstein searched for in vain
for his GUT theory., Its inclusion in the laws of the masters was by
mathematical derivitation where they could not devine it even tho it
is one of the basic four forces of the Universe, the CLASSICAL model.
Now with my adaptation of gauss';s law which provides a picture of
radiation the appearance of weak eddy currents give rise to this
unknown weak force. With computers which are based around equilibrium
and Maxwell and now my extension of Gaussian law will provide the
result of that weak force by placing a radiator tipped from right
angles to the earths surface since all inside of a gaussian field MUST
be in equilibrium. If you need more explanation just ask for it or get
hold of a physics professor who is not a ham!
Regards
Art
Art