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