art KB9MZ wrote:

Thus my major lobe needs to be robust between about 10 degtrees and 4
degrees to ensnare most of the communication.

I don't recall you stated which band but I'll assume 20 meters.
Assuming flat terrain (for your Indiana QTH), a single Yagi at 120'
(your maximum possible) would cover these angles best. 140' (or 2
wavelengths high if it is not 20m) would be the optimum heightl to
center your main lobe at 7 degrees.

Two stacked Yagis at 60' and 120' would be better than a single one at
120' or 140' for 4-10 degrees, but obviously this means more work and
expense.

If your terrain is not relatively flat, and if you are lucky to be on a
hill with a gentle slope in the direction of England, the optimum
height will be much less. However you would need to model this using
HFTA in the most recent Antenna Handbook or YT in older editions.

73, Bill W4ZV

Bill,
None of that is really a problem to me.I have multi points to which I
can feed for different patterns depending on the time of the day as
well as option of tilting the array. If I don't get my elmer I will
assume he is not on the air and yes it is twenty meters and I am
located in the couintryside that I understand is the highest between
Chicago and New Orleans and since this is the bread basket of the U.S
the ground loam is excellent. I use 7/8 andrews plus a long length
underground and the tower is hinged in two places
as well as another one for array tilting. I have power gain over a yagi
but I was just curious as to how much more radiation energy was
available to ensnare which Is why I referred to array volume since gain
is really dependant on half power beam width required or one can live
with I once had a 80 foot yagi and with the looseness in my prop pitch
rotor combined with the narrow beam one was never sure if one was
really taking advantage oif gain available. Pretty simple question for
those who know the answer after all you start off with 3 db gain in two
different directions thereffore it would seem to me that a yagi was
only 50% efficient but people are quarrelling about every thing except
the posed question to excuse them selves from real thought. Reg would
have come up with the solution after a bottle of wine after noticing
the english provided by the cue
Regards
Art

wrote:
art KB9MZ wrote:

Thus my major lobe needs to be robust between about 10 degtrees and 4
degrees to ensnare most of the communication.

I don't recall you stated which band but I'll assume 20 meters.
Assuming flat terrain (for your Indiana QTH), a single Yagi at 120'
(your maximum possible) would cover these angles best. 140' (or 2
wavelengths high if it is not 20m) would be the optimum heightl to
center your main lobe at 7 degrees.

Two stacked Yagis at 60' and 120' would be better than a single one at
120' or 140' for 4-10 degrees, but obviously this means more work and
expense.

If your terrain is not relatively flat, and if you are lucky to be on a
hill with a gentle slope in the direction of England, the optimum
height will be much less. However you would need to model this using
HFTA in the most recent Antenna Handbook or YT in older editions.

73, Bill W4ZV

Hi Art,

A few points below, but first just remember that the TOA of any
horizontally polarized antenna is primarily a function of ground
reflections which vary according to height above ground. Previously
you mentioned that your antenna was designed for a TOA of 10 degrees.
That cannot be true except for a specific height above ground. Whether
Yagi, Quad, Log, Rhombic or any non-vertically stacked antenna.
Something like a Sterba curtain is different because it has multiple
elements stacked vertically which CAN be steered by phasing.

art wrote:

yes it is twenty meters and I am
located in the couintryside that I understand is the highest between
Chicago and New Orleans and since this is the bread basket of the U.S
the ground loam is excellent.

1. Absolute height above sea level means nothing. What is important
to TOA is your relative height above the terrain within a mile or two
of your tower. I operated from Colorado for ~30 years and always got a
chuckle from the guys who said, "My antenna is over 1 mile high". In
fact what is important for determining TOA is not height above sea
level but height above surrounding terrain.

2. Ground conductivity has minimal effect on horizontally polarized
ground reflections. You may be thinking of vertically polarized
antennas like verticals where it has a huge effect. HFTA does have
conductivity as an input parameter but it has minimal effect, at least
in my case (average ground versus salt water).

I use 7/8 andrews plus a long length
underground and the tower is hinged in two places
as well as another one for array tilting.

Phsical tilting has minimal effect on the ground reflections for the
angles of interest (4-10 degrees) because the vertical lobe is not very
narrow (typically a Yagi has ~50 degree 3 dB vertical beamwidth). In
other words tilting has a far secondary effect on TOA versus changing
the antenna height. You can prove this to yourself by modeling with a
program like EZNEC (HFTA does not allow tilting because it is
physically impractical and has little effect).

Pretty simple question for
those who know the answer after all you start off with 3 db gain in two
different directions thereffore it would seem to me that a yagi was
only 50% efficient

I believe you're referring to a dipole which has 2+ dB gain over
isotropic in the two directions broadside to the element. If we add ~6
dB from ground reflection gain, we get 8 dB gain over isotropic, but
this is ONLY for a specific TOA which is determined by the antenna's
height above ground. Of course a good Yagi will typically have 25-30
dB Front to Rear, so its backward lobe has very little of the total
energy (far less than 50%).

Bottom line to all of this is that your antenna's height above ground
has the primary influence on TOA. The only other way to "steer" the
vertical lobe is to mount your antenna on a motorized tower (unless you
go to vertically stacked elements and phasing).

Put your single antenna at 120' and the vertical pattern will be
centered on about 9 degrees (assuming flat terrain).

73 & GL!

Bill W4ZV

P.S. Here are some results using HFTA for my 10 meter 3-stack:

http://users.vnet.net/btippett/terrain_&_toas.htm

wrote:
Hi Art,

A few points below, but first just remember that the TOA of any
horizontally polarized antenna is primarily a function of ground
reflections which vary according to height above ground. Previously
you mentioned that your antenna was designed for a TOA of 10 degrees.
That cannot be true except for a specific height above ground. Whether
Yagi, Quad, Log, Rhombic or any non-vertically stacked antenna.
Something like a Sterba curtain is different because it has multiple
elements stacked vertically which CAN be steered by phasing.

That is entirely correct for known technology........... at this time !




art wrote:

yes it is twenty meters and I am
located in the couintryside that I understand is the highest between
Chicago and New Orleans and since this is the bread basket of the U.S
the ground loam is excellent.

1. Absolute height above sea level means nothing. What is important
to TOA is your relative height above the terrain within a mile or two
of your tower. I operated from Colorado for ~30 years and always got a
chuckle from the guys who said, "My antenna is over 1 mile high". In
fact what is important for determining TOA is not height above sea
level but height above surrounding terrain.

It is the highest point for the U.K. period



2. Ground conductivity has minimal effect on horizontally polarized
ground reflections. You may be thinking of vertically polarized
antennas like verticals where it has a huge effect. HFTA does have
conductivity as an input parameter but it has minimal effect, at least
in my case (average ground versus salt water).


Agreed, there was a Australian article that showd that very well



I use 7/8 andrews plus a long length
underground and the tower is hinged in two places
as well as another one for array tilting.

Phsical tilting has minimal effect on the ground reflections for the
angles of interest (4-10 degrees) because the vertical lobe is not very
narrow (typically a Yagi has ~50 degree 3 dB vertical beamwidth). In
other words tilting has a far secondary effect on TOA versus changing
the antenna height.

Lawson W2PV wrote about that while he was working in Schenectady G.E.
on the computor that replaced zillions of vacuum valves but with
respect to planar arrays
Mine is not a planar array




You can prove this to yourself by modeling with a
program like EZNEC (HFTA does not allow tilting because it is
physically impractical and has little effect).

As I said above mine is not a planar array. The computor program I use
is AO-PRO
by Beasley


Pretty simple question for
those who know the answer after all you start off with 3 db gain in two
different directions thereffore it would seem to me that a yagi was
only 50% efficient

I believe you're referring to a dipole which has 2+ dB gain over
isotropic in the two directions broadside to the element.
Yes, I rounded it off to 3


If we add ~6
dB from ground reflection gain, we get 8 dB gain over isotropic, but
this is ONLY for a specific TOA which is determined by the antenna's
height above ground.

Fully undertstood when referring to planar arrays

Of course a good Yagi will typically have 25-30
dB Front to Rear, so its backward lobe has very little of the total
energy (far less than 50%). F/B for planar arrays is for a single angle , front to rear is more appealing but at the same time it ignores pattern lobes in all directions including upwards. I have found that TOA on its own is pretty wothless as one can get the gain of a larger antenna with a wider but narrower lobe that follows the bottom half of a higher gain lobe. Lets face it for planar arrays gain is obtained at the axpense of half power area.


Bottom line to all of this is that your antenna's height above ground
has the primary influence on TOA. The only other way to "steer" the
vertical lobe is to mount your antenna on a motorized tower (unless you
go to vertically stacked elements and phasing).

Obviously height is important and totally constrictive of all planar
arrays where the TOA is captive. As soon as you add another vector such
that the array is three dimensional as with a stack things change

Put your single antenna at 120' and the vertical pattern will be
centered on about 9 degrees (assuming flat terrain).

I assume you mean vertical elevation and yes mine cannot be much over
100 feet
and I will have various lobes available at various TOA's and most
important variable beam depth to accommodate propagation changes as
arrival angles change
Thanks for the contact The most interesting thing that I am looking
forward to is operation at the bottom of the cycle to see if there is
still propagation but only for low angles. As you gat older you look
for any excuse to stay indoors
Art


73 & GL!

Bill W4ZV

P.S. Here are some results using HFTA for my 10 meter 3-stack:

Yup there was an extensive article on that for the NE area where it
shows the impact
of a ground projection on a collective angle.

http://users.vnet.net/btippett/terrain_&_toas.htm

Hi Art,

art wrote:

It is the highest point for the U.K. period

I don't understand. I thought you were in Indiana and wanting to
optimize your path to England.

As I said above mine is not a planar array. The computor program I use
is AO-PRO
by Beasley

That's the best there is in my opinion. You are fortunate to have a
copy since he no longer sells to hams.

Thanks for the contact The most interesting thing that I am looking
forward to is operation at the bottom of the cycle to see if there is
still propagation but only for low angles. As you gat older you look
for any excuse to stay indoors

You're welcome. Here is a long but interesting story related to low
angle TOAs. W3CRA was a legend and I can vividly remember him working
one Asian after another that I could not detect the slightest trace of
using a 3 element Yagi at 60' from my home in NC at that time:

http://users.vnet.net/btippett/w3cra.htm

Good luck with your new system!

73, Bill W4ZV

Just read your page... very interestin. We don't have large hills in
Illinois but a helicoptor pilot stated that this town is visible for
miles around and another ham told me that the DX bureu staed that this
town got more cards than all of Chicago I remember once when I gave a
local talk where I spoke about Lawson and his work and I repeated some
of his statements. Well I was challenged on some things but since I am
not a DXer they and the suurounding counties waited until a rare
station was comming on and taking only three stations from each
district. Boy I got a shock with the noise and pandemonium and couldnt
see how any station could be picked out but I was fortunate plus two in
the Chicago area. I know I was very lucky and have no idea why people
collect those things or enter contests... the noise is horrible I think
I had 13 elements on a 60 foot boom at that time plus a couple of
reflectors to experiment with. From that moment on I gave up on
aluminum elements and now use exclusively telescopic fishing poles with
an aluminum shell as it is cheaper in the long run and not susceptable
to ice build up
Art
Artl
wrote:
Hi Art,

art wrote:

It is the highest point for the U.K. period

I don't understand. I thought you were in Indiana and wanting to
optimize your path to England.

As I said above mine is not a planar array. The computor program I use
is AO-PRO
by Beasley

That's the best there is in my opinion. You are fortunate to have a
copy since he no longer sells to hams.

Thanks for the contact The most interesting thing that I am looking
forward to is operation at the bottom of the cycle to see if there is
still propagation but only for low angles. As you gat older you look
for any excuse to stay indoors

You're welcome. Here is a long but interesting story related to low
angle TOAs. W3CRA was a legend and I can vividly remember him working
one Asian after another that I could not detect the slightest trace of
using a 3 element Yagi at 60' from my home in NC at that time:

http://users.vnet.net/btippett/w3cra.htm

Good luck with your new system!

73, Bill W4ZV

"art" wrote in message

I know I was very lucky and have no idea why people
collect those things or enter contests... the noise is horrible I think
I had 13 elements on a 60 foot boom at that time plus a couple of
reflectors to experiment with.

Art,

Why do people run Marathons, race cars, boats, airplanes or turtles? Some
like to walk, some roll in the mud, some like to compete in the stadium.

Contesters like to prove that they can design better antennas, assemble
better stations and prove that they are better operators. It is also real
test for antenna designs and propagation knowledge and how to exploit both
for better results that can quantify the performance and weed out junk and
junk science. It takes years of devotion to show up in the top ten listings.
If you have revolutionary design, we contesters will be first, dying to use
it and cream the competition - that's the real test and not mumbo-jumbo
claims.

BTW I have a "secret weapon" too, it is a ferrite stick in the dish. Very
efficient, no side lobes, one sharp beam, no side or back lobes. It is right
up there with EH, Freaktals and perpetual motion machines.

If you assume that propagation between you and UK is as you describe, you
are way off. We are also ducting, use skewed path and changing angles
depending on the point in the sunspot cycle, sun' activity, etc. etc. So for
optimum propagation one needs either antenna that has wider beamwidth or
sharp and stearable one in H and V planes.

Can you enlighten us about your new revolutionary invention? Is it better
than your patented reflector that is shorter than the driven element?

73