On Fri, 28 Jan 2005 21:28:20 -0800, Roy Lewallen
wrote:

What does the takeoff angle have to do with which antenna is best?


That would depend on the desired contact. If you want 80 meters DX,
you want a very high antenna, if you just want to talk to your local
buddies, a lower antenna provides a better NVIS.

Verticals provide better omni-directional pattern but a slanted dipole
provides better directivity than a vertical.

Beams are obvious.


--
Buck
N4PGW

*Sigh*

I tried.

Roy Lewallen, W7EL

Buck wrote:
On Fri, 28 Jan 2005 21:28:20 -0800, Roy Lewallen
wrote:


What does the takeoff angle have to do with which antenna is best?



That would depend on the desired contact. If you want 80 meters DX,
you want a very high antenna, if you just want to talk to your local
buddies, a lower antenna provides a better NVIS.

Verticals provide better omni-directional pattern but a slanted dipole
provides better directivity than a vertical.

Beams are obvious.

Jim Lawson, W2PV, solved the TOA problem on 20 M with a l o n g yagi at
~150' to open the band and his either/or/both stack(top antenna at about
70-80', as I remember) for normal band condition. Oh yes, Alpha 77s on most
bands, too!

Phil, KB2HQ, former neighbor of W2PV

" wrote in message
news:ODzKd.33178$IV5.6955@attbi_s54...
You can move the antenna boom up or down some 10 degrees and you would not
be able to tell the difference per
Lawson W2PV
Art
"Buck" wrote in message
...
On 28 Jan 2005 12:48:52 -0800, "art" wrote:

Most people have added an amplifier only to find out that the
difference in signal
was very small. Thus many people deride the value of a 'silly' db gain
whereas DX'ers say that a single db extra is a lot !
Fact is that most long distance signals on 20 metres come in at angles
of 11 degrees or less where as the 'normal' antenna has a TOA of around
14 degrees.
So where a dxer points to the extra 1db gain as being everything in
fact it is the lowering of the TOA that comes with the extra gain. In
my opinion if one designs his antenna for a lower TOA say 10 to 11
degrees then even tho its gain may well be below the dxers choise( a
very long boom or stacked antennas) the lower TOA with less gain will
show little difference
to the antenna of choics because the lower edge of the radiation lobe
will follow the same line and any extra gain provided will have the
same effect of adding an amplifier which is minimal compared to the
ability of capturing signals that arrive at low angles.
I believe it is time for antenna designers to concentrate less on
obtaining gain and instead concentrate more on lowering the TOA.
without the need of excessive real estate requirements.
What say ?
Art


I have always thought that if one changed the azimuth angle of a beam
it would improve a number of contact signals, pending the angle they
are reflected from the atmosphere.


--
Buck
N4PGW

On Fri, 28 Jan 2005 21:28:20 -0800, Roy Lewallen
wrote:

I say ignore the TOA. (For those unfamiliar with the term, it's the
"takeoff angle", which usually means the elevation angle at which the
antenna pattern is strongest.)

What counts is the gain at the elevation angle at which you want to
communicate. This, in turn, depends on the distance and the propagation
conditions. If you need a strong signal at an elevation angle of 15
degrees, it doesn't matter whether the TOA is 10 degrees, 15, or 20 or
zero. All that counts is the gain at 15 degrees. And an antenna with TOA
of 15 degrees doesn't necessarily have the most gain at 15 degrees of
any antenna.

Consider the following three 40 meter antennas: A vertical antenna with
about 8 radials (18 ohm ground system resistance), a dipole at 30 feet,
and a dipole at 40 feet, all over average ground.

Antenna TOA deg Gain at 26 deg. Gain at 15 deg.

Vert 26 -1.76 dBi -2.72 dBi
Dipole @ 30' 90 (straight up) 2.58 dBi -1.28 dBi
Dipole @ 40' 51 3.9 dBi 0.32 dBi

-- Which one has the lowest takeoff angle?
-- Which one is the best for communicating at 26 deg. elevation angle?
-- Which one is the best for communciating at 15 deg. elevation angle?

What does the takeoff angle have to do with which antenna is best?

Roy Lewallen, W7EL

Dear Roy,

3 cheers.


Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html

Roy Lewallen wrote:

*Sigh*

I tried.



Let me have a shot at it, Roy.

possible blather alert!

Perhaps there is confusion by some people with the idea that the
takeoff angle. I suspect that a lot of people think of their RF leaving
the antenna as a "blob" that leaps out at some desired or undesired angle.

Instead, the RF is heading off in all directions, with some angles
having more relative power.

So even if an antenna has a lower TOA, it might be less gain than an
antenna that has a higher TOA has at that angle.

An inefficient antenna with a low TOA can be less efficient at that low
TOA than a more efficient antenna with a higher TOA is at that same low TOA.

Oy.

- Mike KB3EIA -

rest snipped

Mike Coslo wrote:
Perhaps there is confusion by some people with the idea that the
takeoff angle. I suspect that a lot of people think of their RF leaving
the antenna as a "blob" that leaps out at some desired or undesired angle.

Instead, the RF is heading off in all directions, with some angles
having more relative power.

So even if an antenna has a lower TOA, it might be less gain than an
antenna that has a higher TOA has at that angle.

An inefficient antenna with a low TOA can be less efficient at that
low TOA than a more efficient antenna with a higher TOA is at that same
low TOA.

Maybe a picture is worth a thousand words. Here's a comparison
radiation pattern for my 130 ft dipole Vs my 40m vertical with
elevated radials. In the dipole's favored direction, it's TOA
is greater than the vertical's yet the dipole radiates more
power than the vertical even at the vertical's TOA. Here's the
pictu http://www.qsl.net/w5dxp/dipvsver.htm
--
73, Cecil, W5DXP


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On Sat, 29 Jan 2005 13:11:20 GMT, "Phil"
wrote:

Jim Lawson, W2PV, solved the TOA problem on 20 M with a l o n g yagi at
~150' to open the band and his either/or/both stack(top antenna at about
70-80', as I remember) for normal band condition. Oh yes, Alpha 77s on most
bands, too!

Phil, KB2HQ, former neighbor of W2PV


I imagine that you had an interesting ham life when you shared the
same band and he communicated in your direction.


--
Buck
N4PGW

On 28 Jan 2005 12:48:52 -0800, "art" wrote:

Most people have added an amplifier only to find out that the
difference in signal
was very small. Thus many people deride the value of a 'silly' db gain
whereas DX'ers say that a single db extra is a lot !
Fact is that most long distance signals on 20 metres come in at angles
of 11 degrees or less where as the 'normal' antenna has a TOA of around
14 degrees.
So where a dxer points to the extra 1db gain as being everything in
fact it is the lowering of the TOA that comes with the extra gain. In
my opinion if one designs his antenna for a lower TOA say 10 to 11
degrees then even tho its gain may well be below the dxers choise( a
very long boom or stacked antennas) the lower TOA with less gain will
show little difference
to the antenna of choics because the lower edge of the radiation lobe
will follow the same line and any extra gain provided will have the
same effect of adding an amplifier which is minimal compared to the
ability of capturing signals that arrive at low angles.
I believe it is time for antenna designers to concentrate less on
obtaining gain and instead concentrate more on lowering the TOA.
without the need of excessive real estate requirements.
What say ?
Art

Someone correct me if I am wrong, but isn't gain derived by narrowing
focussing all the energy into a more narrow path?

Besides, TOA is important to the location of an antenna in respect to
its relative position to the ground and the surrounding terrain.

I have heard that people surrounded by mountains prefer a 1/4 whip on
their cars for 2 meters and up when trying to hit repeaters due to its
higher angle of radiation, but in the flat areas, the preferred
antennas are the 5/8 wave etc due to its horizontal gain.

Being on the side of a hill, I can't use an antenna at roof-top level
with a low angel of radiation as there isn't enough power to get the
signal through the miles of land mass under my neighbor's houses.

I did an experiment when I first received my General license to see if
I could sign into the GA SSB NTS Net. I rolled out a spool of wire on
the ground approximately 1/4 wave for 3975 kc. Without a tuner I was
able to get acceptable SWR and checked into the net. I wasn't the
strongest signal but I did well enough to hold several QSOs. It
wasn't as good as my dipole when I raised one, but it worked better
than my 40 meter dipole at the time.

I believe that a horizontal dipole will have about the same TOA as a
vertical dipole when both are sufficiently high. However, the dipole
is more bidirectional and the vertical is omni directional. Therefore
the horizontal dipole may display some gain broadside over the
vertical.

I believe that Cecil's picture reinforces the idea that on HF
especially, the TOA is largely affected by the antenna's elevation
above ground.

However, I was reading in CQ or QST last year about a DX operator who
uses verticals near the sea and wins his contests because of his
antennas. He finds the best location for his antennas near the ocean.
I believe he said he had tried beams before but there is an ocean
effect that makes the verticals better suited for his operations.

That same vertical would be lousy for me as my house is on a hill that
forms a very close valley.

I used a Taylor Radio vertical years ago in this yard and it sucked.
However, when I used it in Charleston and Jacksonville, it was
fantastic (not near the ocean).

Another DX operator suggests that most people will have a better
chance of communicating with him if they use a slanted dipole pointed
in the direction of their QTH. The angle of radiation and gain make
it a great DX antenna.

Different antennas work differently depending on their locations. I
think your better question would be, what is the best antenna for my
QTH and operating style?




--
Buck
N4PGW

Buck, in my posting I refered to 20 meters and also the incoming angles and
average signals thereof coming from Europe. Thus my interest was in the
lower half of the main lobe. The thickness of the lobe of the lobe would
thus not be important,
only the contour of the underside of the lobe. It is this portion of the
lobe where a DXer referers to the fact that a db means a lot as opposed to
adding a db gain to angles contained within a lobe. Note that the thickness
of the lobe can vary even tho both anternnas may have the same take of angle
as can be seen by comparing a monster boom length antenna to that of a
stacked beam which admittedly has a feed point which is very high. When
comparing these two types an optimum would be a low feed point (1 WL) with a
small turning radius with means to compress the main lobe downwards for
those DX
signals arrive and where the 'silly' db becomes everything
Regards
Art.




"Buck" wrote in message
...
On 28 Jan 2005 12:48:52 -0800, "art" wrote:

Most people have added an amplifier only to find out that the
difference in signal
was very small. Thus many people deride the value of a 'silly' db gain
whereas DX'ers say that a single db extra is a lot !
Fact is that most long distance signals on 20 metres come in at angles
of 11 degrees or less where as the 'normal' antenna has a TOA of around
14 degrees.
So where a dxer points to the extra 1db gain as being everything in
fact it is the lowering of the TOA that comes with the extra gain. In
my opinion if one designs his antenna for a lower TOA say 10 to 11
degrees then even tho its gain may well be below the dxers choise( a
very long boom or stacked antennas) the lower TOA with less gain will
show little difference
to the antenna of choics because the lower edge of the radiation lobe
will follow the same line and any extra gain provided will have the
same effect of adding an amplifier which is minimal compared to the
ability of capturing signals that arrive at low angles.
I believe it is time for antenna designers to concentrate less on
obtaining gain and instead concentrate more on lowering the TOA.
without the need of excessive real estate requirements.
What say ?
Art

Someone correct me if I am wrong, but isn't gain derived by narrowing
focussing all the energy into a more narrow path?

Besides, TOA is important to the location of an antenna in respect to
its relative position to the ground and the surrounding terrain.

I have heard that people surrounded by mountains prefer a 1/4 whip on
their cars for 2 meters and up when trying to hit repeaters due to its
higher angle of radiation, but in the flat areas, the preferred
antennas are the 5/8 wave etc due to its horizontal gain.

Being on the side of a hill, I can't use an antenna at roof-top level
with a low angel of radiation as there isn't enough power to get the
signal through the miles of land mass under my neighbor's houses.

I did an experiment when I first received my General license to see if
I could sign into the GA SSB NTS Net. I rolled out a spool of wire on
the ground approximately 1/4 wave for 3975 kc. Without a tuner I was
able to get acceptable SWR and checked into the net. I wasn't the
strongest signal but I did well enough to hold several QSOs. It
wasn't as good as my dipole when I raised one, but it worked better
than my 40 meter dipole at the time.

I believe that a horizontal dipole will have about the same TOA as a
vertical dipole when both are sufficiently high. However, the dipole
is more bidirectional and the vertical is omni directional. Therefore
the horizontal dipole may display some gain broadside over the
vertical.

I believe that Cecil's picture reinforces the idea that on HF
especially, the TOA is largely affected by the antenna's elevation
above ground.

However, I was reading in CQ or QST last year about a DX operator who
uses verticals near the sea and wins his contests because of his
antennas. He finds the best location for his antennas near the ocean.
I believe he said he had tried beams before but there is an ocean
effect that makes the verticals better suited for his operations.

That same vertical would be lousy for me as my house is on a hill that
forms a very close valley.

I used a Taylor Radio vertical years ago in this yard and it sucked.
However, when I used it in Charleston and Jacksonville, it was
fantastic (not near the ocean).

Another DX operator suggests that most people will have a better
chance of communicating with him if they use a slanted dipole pointed
in the direction of their QTH. The angle of radiation and gain make
it a great DX antenna.

Different antennas work differently depending on their locations. I
think your better question would be, what is the best antenna for my
QTH and operating style?




--
Buck
N4PGW

On Sat, 29 Jan 2005 10:52:05 -0500, Buck wrote:

Someone correct me if I am wrong, but isn't gain derived by narrowing
focussing all the energy into a more narrow path?

Hi Buck,

Thanks for the invitation (but we are a rabble of party crashers
anyway). What you say about narrowing to achieve gain is a useful
analogy, but there are some problems on down the line:

Besides, TOA is important to the location of an antenna in respect to
its relative position to the ground and the surrounding terrain.

True, except to invert the inference: location and terrain is
important to the TOA (put the horse before the cart, in other words).

I have heard that people surrounded by mountains prefer a 1/4 whip on
their cars for 2 meters and up when trying to hit repeaters due to its
higher angle of radiation, but in the flat areas, the preferred
antennas are the 5/8 wave etc due to its horizontal gain.

This reveals the problem with testimonial in place of measurement.
Unless you are in the Grand Canyon, you stand a chance of
communication at a very much greater distance to a mountain than you
are to another rig on the same plain. Even an HT has enough power to
communicate with a sattelite (or space shuttle). This reveals that
power is not the problem for considerable distance. However, at this
frequency (2M) line of sight on the plains is not that very far away
(less than 5 miles with your HT in your hand). On the other hand, if
on the plains you can see a mountain 50 miles away, you are as likely
as not to be able to talk to it to (presuming a repeater inhabits its
peak).

Hence the gain differential of quarterwave and 5/8ths is not
necessarily required for the Power nor the TOA - other issues are at
work. When the issues are not discussed, nor investigated, then
changing the antenna system from one to the other may resolve that
hidden issue and the difference attributed to the antenna - voila!
testimony offered.

I did an experiment when I first received my General license to see if
I could sign into the GA SSB NTS Net. I rolled out a spool of wire on
the ground approximately 1/4 wave for 3975 kc. Without a tuner I was
able to get acceptable SWR and checked into the net. I wasn't the
strongest signal but I did well enough to hold several QSOs. It
wasn't as good as my dipole when I raised one, but it worked better
than my 40 meter dipole at the time.

You have a bad habit of comparing the qualities of one antenna on one
band to the qualities of a second antenna on another band. This is
called testimonial, and it is not very useful in demonstrating
correlations. Trying to draw two different observations under the
same umbrella of discussion does not lead to any general conclusion.

Your 80M antenna on the ground would match, certainly when so
obviously in the grip of ground. You could have probably qualified
that installation to match at nearly any frequency - if we confine the
goal of matching to present no reflected power. A ground hugger so
qualifies and the ground is content to absorb (without reflecting) all
the power you pour into it.

What you fail to compare is how it worked "better" than your elevated
40M: how far were you working 80M contacts? The ground laid antenna
was used in Desert Storm for just this quality and it provided useful
contacts in missions there, but they were not interested in skip.

However, I was reading in CQ or QST last year about a DX operator who
uses verticals near the sea and wins his contests because of his
antennas. He finds the best location for his antennas near the ocean.
I believe he said he had tried beams before but there is an ocean
effect that makes the verticals better suited for his operations.

This, again, is testimonial. However, it is often attended with
compelling testing and theory that dovetail. The simple explanation
is that the vertical's radiation is constructively reinforced at low
angles by the sea, a horizontal's radiation is destructively combined
by the sea at low take off angles. The difference at very low angles
is far in excess of a 'little' db.

If you look over your shoulder to all that sand behind you, then that
same vertical becomes a miserable performer in comparison to those
beams turned to follow your eye.

Another DX operator suggests that most people will have a better
chance of communicating with him if they use a slanted dipole pointed
in the direction of their QTH. The angle of radiation and gain make
it a great DX antenna.

It's surprising how many Hams have missed this gem of wisdom. It must
mean that
1. We are a particularly dull and stupid lot;
or
2. It doesn't really offer all that much for the effort.

73's
Richard Clark, KB7QHC