Art wrote:
"I have modelled a similar arrangement in Gaussian form where the
elements are bent into a Vee shaped like Yagi with elements extremely
close together where it provides exceptional gain and pattern and can
be related visually to a bent long boom but without elements."

There is a TV antenna something like that on a rooftop within 2 blocks
from here. IIt must have some exceptional characteristic. Someone built
it. The elements are short compared to several wavelengths at 200 MHz.

Does the model result in a low deivepoint impedance?

Does the Vee result in high response off the tips of the elements?

Does close coupling between elements result in great bandwidrh for the
antenna?

Best regards, Richard Harrison, KB5WZI

On 30 May, 19:41, (Richard Harrison) wrote:
Art wrote:

"I have modelled a similar arrangement in Gaussian form where the
elements are bent into a Vee shaped like Yagi with elements extremely
close together where it provides exceptional gain and pattern and can
be related visually to a bent long boom but without elements."

There is a TV antenna something like that on a rooftop within 2 blocks
from here. IIt must have some exceptional characteristic. Someone built
it. The elements are short compared to several wavelengths at 200 MHz.

Does the model result in a low deivepoint impedance?
No, as I remember it was of high impedance

Does the Vee result in high response off the tips of the elements?
That is out of my realm in knowledge since I do not know how one
measures that with ccommonly known units that is accepted in the
trade

Does close coupling between elements result in great bandwidrh for the
antenna?

Yes it did but you are thinking in terms of a yagi where element
spacing is a dominant factor for the focussing effect.
That is certainly not the case for a gaussian antenna where
spacing is not the dominant factor because of equilibrium demands.
Thus spacings can be very close as long as
the current flow direction in both radiators are in concert with
each other i.e. in equilibrium.
As I have previously said the Gaussian aproach gives
a constant gain which is in concert with other data desirables
which does not require compromises to be sort. The ARRL antenna book
have
a chapter devoted to this problem where three antenna designs
are created for desirables and the final design that with
compromises was the best that one could attain. This is always
the problem with yagi designs in that some covet certain desirables
where others contend they are not important. That's life.
The vee shaped length was 1.5 WL where the center current
curve is manipulated for best results. In a way it is
like an extended Zepp with respect to current pattern and the
radiation pattern is similar to a long boom yagi. For a normal
Gaussian antenna the max gain is equivalent to less than 20 feet
with three elements( 20 M ant ) and does not increasein length
or gain regardless of how many elements are added in search
of gain where as the yagi can be of infinite length in the
search of gain at the expense of beam width.
The Gaussian by the way pretty much maintains a 65 degree
beam width tho with extra ordinary methods such as the vee design
it can reduce to half of that. Why I do not know.
Regards
Art

Best regards, Richard Harrison, KB5WZI

On Wed, 30 May 2007 21:41:03 -0500, (Richard
Harrison) wrote:

Does the model result in a low deivepoint impedance?

Hi Richard,

No more nor less than by the consideration of classical designs.

Does the Vee result in high response off the tips of the elements?

This and the next draw the answer together:

Does close coupling between elements result in great bandwidrh for the
antenna?

Coupling? No, but the bandwidth is in gain, not match (which can be
taken care of by other means). The V shape takes the higher
frequency's tendency to become endfire and aligns it with the boom
(meaning the forward gain at higher frequency is still towards the
front instead of being off the ends of a standard, orthogonal design).
Think how the V shape of the Rhombic brings the lobe towards the major
axis. At the lower frequency, the V angle doesn't matter much and so
the forward gain is still aligned with the boom.

Something of a parasitic half Rhombic (or parasitic V).

73's
Richard Clark, KB7QHC

Richard Clark, KB7QHC wrote:
"Sonething of a parasitic half Rhombic (or parasitic V)".

Yes, but the rhombic or Vee antenna usually needs sides which are
wavelengths long to produce significant gain. I don`t know what Art has
proposed. The TV antenna on the roof near me looks like a Yagi with its
elements all bent to the same angle with the boom. Their lengths aren`t
multiwavelength even at 200 MHz. Maybe at UHF? VHF gain would depend on
phasing between the reflector and the driven element, and the multiple
directors and the driven element. Thus its performance would begin with
its similarity with the straight Yagi, I`d wager.

Before cable and satellite were available, many configurations were
tried for TV. Some were sold more on appearance than performance.

It`s tough to cover a 4 to 1 frequency range smoothly, but they tried.
Some produced decent pictures at some distance from the transmitters
over many VHF channels. Amazing!

Best regards, Richard Harrison, KB5WZI

On Fri, 1 Jun 2007 14:37:32 -0500, (Richard
Harrison) wrote:

Richard Clark, KB7QHC wrote:
"Sonething of a parasitic half Rhombic (or parasitic V)".

Yes, but the rhombic or Vee antenna usually needs sides which are
wavelengths long to produce significant gain.

I was responding to your TV antenna example that exhibited the V shape
with parasitics. The long and short wavelengths both point along the
major axis.

I don`t know what Art has proposed.

Nobody does.

The TV antenna on the roof near me looks like a Yagi with its
elements all bent to the same angle with the boom. Their lengths aren`t
multiwavelength even at 200 MHz. Maybe at UHF?

Exactly.

VHF gain would depend on
phasing between the reflector and the driven element, and the multiple
directors and the driven element. Thus its performance would begin with
its similarity with the straight Yagi, I`d wager.

Exactly (but probably not with any spectacular gain for all the
elements).

73's
Richard Clark, KB7QHC