"Reg Edwards" wrote
The elevation angle of a radio wave is not related to antenna
construction.

It is calculated by trigonometry and is geometrically related to the
distance between two points on the Earth's surface, the height of the
ionospheric reflecting layers involved, and the number of hops.

If a radio wave leaves the Earth at one end of the path and returns to
Earth
at the other end, then the elevation angles of the path taken are the same
at both ends. And the same in the other direction. (To forestall
nitpickers let it be said things can vary around averages.)

The optimum angle at which to point a radio antenna, either for transmit
or
receive, is obviously the same as the elevation angle of the radio path.

BUT NO AMOUNT OF WAVING THE ANTENNA ABOUT WILL AFFECT THE ELEVATION ANGLE
OF
THE RADIO PATH.

For given points on the Earth's surface, height of reflecting layer, and
number of hops, the angle of elevation of the radio path is fixed.

The angle at which the radiation from an antenna is a maximum is an
entirely
different matter.

Calculation of a path elevation angle on a curved Earth not very difficult
but is a little too complicated to be written here.

Up to 1500 groundpath miles the Earth can be considered to be flat. Trig
calculation is then schoolkids stuff.

Full formulae can be found in maths books under "Spherical Trigonometry"
or
in practical radio engineering books.

Calculations can be interesting but are invariably roughly approximate
because layer height involves guesswork. And by the time you've finished a
calculation the height has shifted. Or the number of hops has changed from
2
to 3. The only things which remain static are your own latitude and
longitude.

To calculate propagation statistics of one and two hop radio paths,
including elevation angles, download simple program TWOHOPS in a few
seconds
from website below and run immediately.
----
.................................................. .........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. .........

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

Why should my answer to the question be altogether different to everybody
else's? Especially as I'm right.
---
Reg.

"Reg Edwards" wrote in message
...

"Reg Edwards" wrote
The elevation angle of a radio wave is not related to antenna
construction.

It is calculated by trigonometry and is geometrically related to the
distance between two points on the Earth's surface, the height of the
ionospheric reflecting layers involved, and the number of hops.

If a radio wave leaves the Earth at one end of the path and returns to
Earth
at the other end, then the elevation angles of the path taken are the
same
at both ends. And the same in the other direction. (To forestall
nitpickers let it be said things can vary around averages.)



Reg.
You asre concentrating on things that you can do nothing about
i.e.the ionisphere and trivialising the things that you CAN do something
about
which is TOA, the subject of this thread.

If the transmitting station TOA is low enough to make the QSO in one hop
and the receiving station antenna has a higher take off angle that requires
exactly two hops to reply then the paths are NOT the same.
I would also doubt that the paths taken when being bent by the reflecting
layers
would be the same as the density is subject to change
.. The real discussion regarding TOA is to achieve a QSO
with one hop instead of two so as to cut down on travel losses and that is
where
the importance of TOA and associated angles that follow the +/- 3 db takes
place.
Regardless of the physical position of the antenna the elevation angle of
the radio wave
IS related to antenna construction.
Just a different view point Reg, the antenna I CAN do something about.
Natures actions
I can do NOTHING about except to have the correct equipment when good
conditions occur
and that is where TOA gains it importance.
In my designs I try to have the lowest contour of the bottom lobe even tho
it may mean
a loss of a db in gain at the actual TOA.and I do not concern myself with
the technical data
that your posting revolves about, which tho it may be interesting to some,
as I cannot change it
Nothing personal nor am I nitpicking
Cheers
Art





The optimum angle at which to point a radio antenna, either for transmit
or
receive, is obviously the same as the elevation angle of the radio path.

BUT NO AMOUNT OF WAVING THE ANTENNA ABOUT WILL AFFECT THE ELEVATION ANGLE
OF
THE RADIO PATH.

For given points on the Earth's surface, height of reflecting layer, and
number of hops, the angle of elevation of the radio path is fixed.

The angle at which the radiation from an antenna is a maximum is an
entirely
different matter.

Calculation of a path elevation angle on a curved Earth not very
difficult
but is a little too complicated to be written here.

Up to 1500 groundpath miles the Earth can be considered to be flat. Trig
calculation is then schoolkids stuff.

Full formulae can be found in maths books under "Spherical Trigonometry"
or
in practical radio engineering books.

Calculations can be interesting but are invariably roughly approximate
because layer height involves guesswork. And by the time you've finished
a
calculation the height has shifted. Or the number of hops has changed
from
2
to 3. The only things which remain static are your own latitude and
longitude.

To calculate propagation statistics of one and two hop radio paths,
including elevation angles, download simple program TWOHOPS in a few
seconds
from website below and run immediately.
----
.................................................. .........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. .........

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

Why should my answer to the question be altogether different to everybody
else's? Especially as I'm right.
---
Reg.

Aunwin, we are talking about two different things.

If I want to communicate (optimally) with another station it is important
that I know the direction and elevation angle at which to point my antenna
such that the radio beam preferentially returns to Earth in the vicinity of
the other station.

Direction is found from a map of the Earth's surface plus a magnetic
compass.

The ONLY way to find the elevation angle is to CALCULATE it from the ground
path distance between the two stations, the height of the reflecting layer,
and the number of hops along the path.

It's purely a matter of Spherical Geometry. It has nothing to do with where
your antenna happens to be pointing. Or even whether or not you have an
antenna.

All good radio engineers do it that way. Caculating formulae can be found in
practical radio engineering books. Eznec won't tell you.

Use simple program TWOHOPS to do common calculations. Results are as
accurate as the inevitably uncertain input data.
---
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

Reg, G4FGQ wrote:
"It`s purely a matter of Spherical Geometry"

Edmund A. Laport agrees with Reg in his book "Radio Antenna
Engineering". On page 227 Ed writes:
"If, for example, the computed vertical beam angle for a one-hop circuit
uses 6 degrees at an azimuth of 332 degrees and the horizon in this
direction consisted of a mountain range with a height of 8 degrees, the
performance of the circuit would be greatly compromised by the
obstruction of the mountains. In such a case it might be better to work
this circuit with two hops. Then a vertical beam angle of 20 degrees can
be used instead, with adequate horizon clearance for the wave path. Or
if the circuit required 6 degrees for a two-hop circuit 5400 kilometers
long, with the same obstruction cited, one could change to a three-hop
circuit which for the same layer height would permit the use of a beam
at 14 degrees."

Best regards, Richard Harrison, KB5WZI

"Richard Harrison" wrote in message
...
Reg, G4FGQ wrote:
"It`s purely a matter of Spherical Geometry"

Edmund A. Laport agrees with Reg in his book "Radio Antenna
Engineering". On page 227 Ed writes:
"If, for example, the computed vertical beam angle for a one-hop circuit
uses 6 degrees at an azimuth of 332 degrees and the horizon in this
direction consisted of a mountain range with a height of 8 degrees, the
performance of the circuit would be greatly compromised by the
obstruction of the mountains. In such a case it might be better to work
this circuit with two hops. Then a vertical beam angle of 20 degrees can
be used instead, with adequate horizon clearance for the wave path. Or
if the circuit required 6 degrees for a two-hop circuit 5400 kilometers
long, with the same obstruction cited, one could change to a three-hop
circuit which for the same layer height would permit the use of a beam
at 14 degrees."

Best regards, Richard Harrison, KB5WZI



OR ....... you take advantage of diffraction abilities of physical parts
such as
mountain edges or other physical parts that can deflect the rays AFTER it
leaves
the FEED POINT which does NOT exclude an antenna array of which the feed
point
is part. The point of confusion emanates from.calculating hop distance on
the
basis of a :"standard:". TOA The "magic" of a stacked antenna exposes
the difference
:that occurs with a different TOA.
I suppose you could use Reg's program so that when the ideal conditions do
occur
maybe after several hours of waiting , when one can say that the upper
layers are now
exactly such or such a height and the assumption used in formulating the
program
are now correct. The fact is that ham radio is about formulating an array
that will
provide the hop distance required by the operator since that is something
he can change.
I am quite sure that LaPorte does NOT say that no amount of shaking an
antenna can
change the hop distance which is what TOA is all about and the subject of
this thread.
Maybe we need another thread to clarify the question that Reg and yourself
are
apparently addressing.

Art

Reg, G4FGQ wrote:
"It`s purely a matter of Spherical Geometry."
The ARRL agrees with Reg. The 19th edition of the ARRL Antenna Book on
page 23-24 gives path distance versus vertical wave angle for a one-hop
transmission using the F2 layer in Fig 23. Of course these are only
based on a variable reflecting layer height.

For 500 miles, 40 to 70 degrees.

For 1000 miles, 20 to 35 degrees.

For 1500 miles, 10 to 22 degrees.

For 2000 miles, 4 to 15 degrees.

For 2500 miles, less than 8 degrees.

Neither elevation nor azimuth angles are exact as the wave is subject to
detours but it helps to have an idea of the usual best angles.

Best regards, Richard Harrison, KB5WZI

Reg, when I penned the thread beginnings I was trying to evoke
fresh thinking about the subject so as to challenge ideas that are spread by
plagurism in a similar way that the ballon is shown to demonstrate how
directivity /gain occurs.
Ham radio operators are lead to believe that the height above ground of
a beam's feed point determines the take off angle. It is true that it does
have an effect on the TOA, say 75 percent, when other actions are taken
to change the angle and 95 percent or so if no other actions are taken.
Thus if actions are taken to lower the TOA one can take advantage of
physical hops that were not available for a similar feed point height.
This is why I returned to the thread to dispute the statement that you
made regarding no amount of antenna waving can change the facts.
Regards from another indentured apporentice from the school of
Engineering and Navigation along side of the East India Docks
which was attended by many from the cable company further
down the river
Art







Edwards" wrote in message
...

"Reg Edwards" wrote
The elevation angle of a radio wave is not related to antenna
construction.


snip

BUT NO AMOUNT OF WAVING THE ANTENNA ABOUT WILL AFFECT THE ELEVATION ANGLE
OF
THE RADIO PATH.

snip.
----
.................................................. .........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. .........

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

Why should my answer to the question be altogether different to everybody
else's? Especially as I'm right.
\
Possibly because you were addressing a different question




---
Reg.