On Sat, 05 Mar 2005 14:34:11 GMT, "
wrote:

Thus TOA becomes
the most important thing for me as well as the "thickness" of the lobe.
That is the sense that your response questioned regarding my maximisation
of
antenna
performance for which I use TOA.

Hi Art,

Back when fractal antennas ruled the sky - at least on paper - the
bragging rights were carefully tailored to fit the design.

Some of this was arguably targeted to a user population that would
have enjoyed the advantage. Anyway, such an example is shown at:
http://www.qsl.net/kb7qhc/antenna/fr...r/k2/index.htm

The fractal flyer, and its superior, simpler cousin the H Flyer showed
a real, improved, DX response at 10 degrees. This was not their best
response angle which you call TOA. In fact, both designers studiously
ignored what you call TOA because it was not particularly notable.

So, as a bald statement, both designs constitute very small antennas
that exhibit BETTER gain figures at a TOA of 10 degrees than a full
sized dipole held at a comparable height. Also, these antennas show a
F/B that is very much better than a full sized antenna. Further, both
designs, but notably the H Flyer, show full band matching. However,
having said that, sans actual response levels or context, is having
said nothing.

However, let's look at the full characteristics, not simply the
claims:

Best Response:
Std Dipole 0 dBi @ 90°
fractal flyer -0.81 dBi @ 39°
H Flyer -0.6 dBi @ 45°

10 Deg. Response:
Std Dipole -7.51 dBi
fractal flyer -4.85 dBi
H Flyer -4.75 dBi

2:1 Match Range:
Std Dipole 0.85 MHz
fractal flyer 0.5 MHz
H Flyer 1.0 MHz

As can be seen, the H Flyer was the best design across the board, IF
you accepted the limitations originally imposed (very low, very small,
and scrutinized at 10 degree take off). Does this qualify it as a
good antenna? Depends on if you are space and height limited.

One last point, as poor as a valuation of -5dBi is, there are very few
designs (barring the two shown here) that can perform better and still
fit in the box.

So, let's return to claims, especially for the H Flyer:
Smallest resonant antenna;
Highest DX Gain;
Widest Bandwidth:
Best F/B;
Not a Fractal.

73's
Richard Clark, KB7QHC

An equation that I find useful when starting to think about a tradeoff
between antenna height of a horizontally polarized antenna and performance
is:

Beta-N = ArcSin(N * 74.948/H * F)

N is an integer. H is the height of a horizontal antenna above a flat,
perfectly reflecting surface in meters. F is the frequency of operation in
MHz. Beta-N is in degrees.

For N = 0, 2, 4, 6 ..., Beta-N is the angle above the horizon of a
(theoretical) null.

For N = 1, 3, 5 ..., Beta-N is the angle above the horizon of a maximum.

I store this equation in my calculator and can solve for any of the
variables. Thus: at 18 MHz, it takes a height of 32.2 meters to have the
first null (above the horizon itself) at 15 degrees (N=2) - and, at the
same height, the first peak (N=1) will be at 7.4 degrees.

Of course, the earth is not flat and is not perfectly reflecting (even for
horizontally polarized waves) and so on ... However, this equation helps
with a first cut.

[For those who use feet, the coefficient is 245.89 rather than 74.948.]

73, Mac N8TT
--
J. Mc Laughlin; Michigan U.S.A.
Home:

I really do not understand what you are getting at.
Your antennas are very small but are outside my interests.

I am looking for as long a hop that I can get on 20 meters
and ofcourse it must accept power.Beyond a 80 foot boom I am
constricted , thus I work backwards and start off with a smaller
antenna to which I apply changes in design to obtain the equivalent
of a 60 foot antenna based on the contour of the main lobe bottom.
( this includes changing the structure so that the gain and
front to back maximises at the same frequency
which is where the f/b is really meaningfull )

This is a long, long way from what you are describing and I might add that
my antenna design must be multi banded when I have attained the 60 foot boom
equivalency. Armed with this achievement I can now proceed to attacking
the
problem of exceeding the 60 foot boom yagi performance by using the now
freed
up land space

Can you re phrase your posting, possibly from a different direction, exacty
what
you are trying to add to this thread especially where it affects what I have
posted.
Regards
Art

ard Clark" wrote in message
...
On Sat, 05 Mar 2005 14:34:11 GMT, "
wrote:

Thus TOA becomes
the most important thing for me as well as the "thickness" of the lobe.
That is the sense that your response questioned regarding my maximisation
of
antenna
performance for which I use TOA.

Hi Art,

Back when fractal antennas ruled the sky - at least on paper - the
bragging rights were carefully tailored to fit the design.

Some of this was arguably targeted to a user population that would
have enjoyed the advantage. Anyway, such an example is shown at:
http://www.qsl.net/kb7qhc/antenna/fr...r/k2/index.htm

The fractal flyer, and its superior, simpler cousin the H Flyer showed
a real, improved, DX response at 10 degrees. This was not their best
response angle which you call TOA. In fact, both designers studiously
ignored what you call TOA because it was not particularly notable.

So, as a bald statement, both designs constitute very small antennas
that exhibit BETTER gain figures at a TOA of 10 degrees than a full
sized dipole held at a comparable height. Also, these antennas show a
F/B that is very much better than a full sized antenna. Further, both
designs, but notably the H Flyer, show full band matching. However,
having said that, sans actual response levels or context, is having
said nothing.

However, let's look at the full characteristics, not simply the
claims:

Best Response:
Std Dipole 0 dBi @ 90°
fractal flyer -0.81 dBi @ 39°
H Flyer -0.6 dBi @ 45°

10 Deg. Response:
Std Dipole -7.51 dBi
fractal flyer -4.85 dBi
H Flyer -4.75 dBi

2:1 Match Range:
Std Dipole 0.85 MHz
fractal flyer 0.5 MHz
H Flyer 1.0 MHz

As can be seen, the H Flyer was the best design across the board, IF
you accepted the limitations originally imposed (very low, very small,
and scrutinized at 10 degree take off). Does this qualify it as a
good antenna? Depends on if you are space and height limited.

One last point, as poor as a valuation of -5dBi is, there are very few
designs (barring the two shown here) that can perform better and still
fit in the box.

So, let's return to claims, especially for the H Flyer:
Smallest resonant antenna;
Highest DX Gain;
Widest Bandwidth:
Best F/B;
Not a Fractal.

73's
Richard Clark, KB7QHC

On Sun, 06 Mar 2005 04:25:06 GMT, "
wrote:

Can you re phrase your posting, possibly from a different direction, exacty
what
you are trying to add to this thread especially where it affects what I have
posted.
=
both designs exhibit BETTER gain figures at a TOA of 10 degrees than a full
sized dipole held at a comparable height. However,
having said that, sans actual response levels or context, is having
said nothing.

If you neglect giving us response levels, or context (like height,
length, frequency, ground conditions) then telling us you have a great
10 degree TOA is meaningless.

More to the matter of the thread, it you cannot tell us antenna
location and that location of the intended DX, and the height of the
skip layer, then a great 10 degree TOA could easily be useless.

If this is simply about bragging rights that knowing the DX location
is inconsequential because you will hit somebody, that could as easily
be said about a great 20 degree TOA antenna which makes the great 10
degree TOA antenna another face in the crowd.

73's
Richard Clark, KB7QHC

Beta-N = ArcSin(N * 74.948/H * F)

The equation is not doubted.
Could somebody please check that Eznec nulls at N=2 and N=4 agree with it
above a perfect ground.
----
Reg, G4FGQ

"J. Mc Laughlin" wrote

Beta-N = ArcSin(N * 74.948/H * F)

=========================

Mac, you are of the same heart as myself.

If you have an equation simple enough to write here which computes the
relative magnitudes of the maximums, could you please oblige?

I could write a program which incorporates it.
----
Reg, G4FGQ

"J. Mc Laughlin" wrote

Beta-N = ArcSin(N * 74.948/H * F)

=========================

There are two typing errors in the above equation.

Beta-N does not mean Beta minus N.
It just means the N'th value of Beta.

And the intended equation should be -

Beta = ArcSin(74.948*N/H/F) degrees.

Alternatively,

Sin(Beta) = 74.948*N/H/F degrees.

That is, divide by F, NOT multiply by F.
----
Reg, G4FGQ

Now I understand where you are coming from !.
I've given a lot of info out about the antenna
and its attributes, many of which are unique.
Also why I am following this path
I do not consider these posts mention of the attributes such as
feed point height or details regarding F/B as meaningless
and certainly not points about which to argue.
I did ask on another posting if there was anything written on a particular
subject regarding a particular feature but there was no response so there is
not a lot of interest in some aspects
If I have declared something that is impossible I would be happy to debate
it
but at this point I am not ready to publish all details which I am sure that
you
understand
Art








"Richard Clark" wrote in message
...
On Sun, 06 Mar 2005 04:25:06 GMT, "
wrote:

Can you re phrase your posting, possibly from a different direction,
exacty
what
you are trying to add to this thread especially where it affects what I
have
posted.
=
both designs exhibit BETTER gain figures at a TOA of 10 degrees than a
full
sized dipole held at a comparable height. However,
having said that, sans actual response levels or context, is having
said nothing.

If you neglect giving us response levels, or context (like height,
length, frequency, ground conditions) then telling us you have a great
10 degree TOA is meaningless.

More to the matter of the thread, it you cannot tell us antenna
location and that location of the intended DX, and the height of the
skip layer, then a great 10 degree TOA could easily be useless.

If this is simply about bragging rights that knowing the DX location
is inconsequential because you will hit somebody, that could as easily
be said about a great 20 degree TOA antenna which makes the great 10
degree TOA antenna another face in the crowd.

73's
Richard Clark, KB7QHC

Providing actual values should have resolved any latent ambiguity.
Nevertheless, I should have assumed the use of a TI calculator.

Beta-sub-N = ArcSin( (N * 74.948)/(H * F))

The argument of the ArcSin is the product of N times the indicated
coefficient all divided by the product of the height times the frequency.

Height is in meters. Frequency is in MHz. N is an integer. Even values of
N apply to nulls. Odd values of N apply to peaks. Beta-sub-N is an angle
in degrees measured from the horizon towards the zenith.

The equation assumes an isotropic*, purely horizontally polarized antenna;
and a ground that is flat and has a reflection coefficient of minus-one for
an incident horizontally polarized wave independent of the
angle-of-incidence.

* Note: In this context, isotropic is to be understood to mean broadside
gain is constant and is independent of angle.

Fortunately, broadside to most horizontally antennas and for most
grounds, the conditions are close to being satisfied for Beta up to perhaps
30 degrees. The angles that are important for "DX," I have found to be
between two and twelve degrees. In other words, if long distance contacts
are desired, it is desirable to have most of an antenna's gain be between 2
and 12 degrees above the horizon.

Consider the person who places a 14.2 MHz Yagi at 60 meters (the magic
height above which one has to deal with the FAA). As a first approximation,
such an antenna is expected to have a peak at about 5 degrees and a null at
about 10 degrees. When the band opens, such a system is likely to dominate.
When propagation is better, those with lower antennas might have more gain
at the useful angle.

73 Mac N8TT
--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Reg Edwards" wrote in message
...

"J. Mc Laughlin" wrote

Beta-N = ArcSin(N * 74.948/H * F)

=========================

There are two typing errors in the above equation.

Beta-N does not mean Beta minus N.
It just means the N'th value of Beta.

And the intended equation should be -

Beta = ArcSin(74.948*N/H/F) degrees.

Alternatively,

Sin(Beta) = 74.948*N/H/F degrees.

That is, divide by F, NOT multiply by F.
----
Reg, G4FGQ

"J. Mc Laughlin" wrote in message
...
snip

.. The angles that are important for "DX," I have found to be
between two and twelve degrees. In other words, if long distance contacts
are desired, it is desirable to have most of an antenna's gain be between
2
and 12 degrees above the horizon.


At last reason prevails.......
For DX purposes only the bottom half of the
main lobe is usefull. If your TOA is 13 to 14 degrees which is average
then more than 50 percent of the main lobe is serving no purpose.

If one wants to capture the highest possible number
of DX contacts then the TOA should be the angle where the
upper side of the main lobe is 3db down from the TOA.
Lower than this point renders the antenna useless as propagation sets in.
Mac shows this with a antenna having a TOA at 5 degrees that
has a theoretical NULL at 10 degrees which means 50 percent of
incoming signals are not available to the antenna user



Consider the person who places a 14.2 MHz Yagi at 60 meters (the magic
height above which one has to deal with the FAA). As a first
approximation,
such an antenna is expected to have a peak at about 5 degrees and a null
at
about 10 degrees. When the band opens, such a system is likely to
dominate.
When propagation is better, those with lower antennas might have more gain
at the useful angle.

73 Mac N8TT
-- Reg, G4FGQ

Regards

Art