Incoming signal elevation question
 

Yuri Blanarovich wrote:
I have seen situations when signals to Europe were coming under low angle
and in the same direction, signals to deep Asia were coming under higher
angle at the same time.

Seems to me a rotatable dipole with the ability to also
rotate from horizontal to vertical would be a good thing
to have.
--
73, Cecil http://www.qsl.net/w5dxp

Incoming signal elevation question
 

"Yuri Blanarovich" wrote in message
...
Reg wrote:
The type of antenna or its radiation pattern has nothing whatever
to
do with the path taken by the radio wave through the ionosphere.
The
take-off angle and its name, generated by EZNEC, can be very
misleading.


It has to do. It allows us to direct the RF under desired angle to
hit the
layer or region that supports the propagation to the chosen target.
=========================================
Yuri,

The elevation angle of the radio path from the transmitter on its way
to the target changes with the number of hops.

How does Eznec know the number of hops? How does Eznec know which
angle is correct? How does Eznec know the height of the reflecting
layers? How does Eznec know the distances at which the radio wave
returns to Earth to be re-reflected?

Eznec doesn't know. And neither does the radio operator unless he
estimates everything AFTER the event.

Radio waves follow paths dictated by trigonometry and geometry and are
entirely independent of the idiosyncrasies of radio antennas.
----
Reg.

Incoming signal elevation question
 

On Wed, 17 May 2006 20:15:24 +0100, "Reg Edwards"
wrote:

The elevation angle ... changes
....
Radio waves follow paths dictated by trigonometry and geometry
a curious trig and geometry at that
entirely independent of the idiosyncrasies of radio antennas.
and unzipped software propagation forecasters too?

Hi Reggie,

I especially enjoy how you attempt to poison the restaurant to kill
waiter:
How does Eznec know
How does Eznec know
How does Eznec know
How does Eznec know
Eznec doesn't know
Which presumes a claim (four of them in fact) not made (except by you,
but then anyone can put antenna modeling tools to foolish propagation
uses).

I won't ask for substantiation on your geometry, Lord Kelvinator has
turned his back on these absurd proceedings too. I will leave you
with the last exasperated gasp.

73's
Richard Clark, KB7QHC

Incoming signal elevation question
 

"Reg Edwards" wrote in message
...

"Yuri Blanarovich" wrote in message
...
Reg wrote:
The type of antenna or its radiation pattern has nothing whatever
to
do with the path taken by the radio wave through the ionosphere.
The
take-off angle and its name, generated by EZNEC, can be very
misleading.


It has to do. It allows us to direct the RF under desired angle to
hit the
layer or region that supports the propagation to the chosen target.
=======================================
Yuri,

But you can't "direct" it.

You have to do your best with whatever elevation angle Eznec dictates.
----
Reg.


You bet I can, I can do that with stacked antennas, rotatable, polarization
switchable, phasing, crank up tower changing height antennas - and by what
antenna design and surroundings dictate, not EZNEC. EZNEC gives approximate
picture of radiation pattern produced by antenna model. Real life (ground
conditions, surroundings) changes the antenna pattern.
So I would be carefull giving EZNEC absolute powers dictating anything :-)
Combined with terrain analysis software, it will give better picture of
where the antenna projects the signal.

73 Yuri, K3BU

Incoming signal elevation question
 

"Reg Edwards" wrote in message
...

"Yuri Blanarovich" wrote in message
...
Reg wrote:
The type of antenna or its radiation pattern has nothing whatever
to
do with the path taken by the radio wave through the ionosphere.
The
take-off angle and its name, generated by EZNEC, can be very
misleading.


It has to do. It allows us to direct the RF under desired angle to
hit the
layer or region that supports the propagation to the chosen target.
=========================================
Yuri,

The elevation angle of the radio path from the transmitter on its way
to the target changes with the number of hops.


The ionospheric propagation is not that clear cut simple, it is very
complicated. We have reflections going on and we have refractions going on
in the media that is like stormy sea. With the same height layer, and
uniform conditions, you can have more hops under higher launching angle, or
you can have fewer hops under lower angles. There could be another higher
layer with more complications of ducting or "bouncing" between the layers.

How does Eznec know the number of hops? How does Eznec know which
angle is correct? How does Eznec know the height of the reflecting
layers? How does Eznec know the distances at which the radio wave
returns to Earth to be re-reflected?

EZNEC knows sheeet about propagation. EZNEC and other antenna modeling
software can calculate the radiation pattern of modeled (not real) antenna
according to given ground parameters and antenna geometry. It gives you idea
how the pattern looks, but not the where the signal goes after entering
propagation media.

Eznec doesn't know. And neither does the radio operator unless he
estimates everything AFTER the event.


I know based on my experience operating at various times in the sunspot
cycle and my knowledge of propagation. There are now quite good propagation
programs that based on propagation indices and flux numbers, can give rough
idea where is the bulk of propagating going. Extreme antennas can do one
better, propagate where software doesn't think you can.

Radio waves follow paths dictated by trigonometry and geometry and are
entirely independent of the idiosyncrasies of radio antennas.
----
Reg.

Very fuzzy trig and geometry, it is not polished mirrors out there, it is
fuzzy bunch of ion-clouds like "hamburgers" that do their thing massaging
the signals. By using antennas that have stearable pattern, vertically and
horizontally one can take advantage of various modes of propagation. So it
takes natenna "idiot syncracies" to dictate where the signal goes, and how
it will propagate, conditions permitting.
See my article on "conducting" way back in CQ Magazine
http://members.aol.com/ve3bmv/bmvpropagation.htm

Yuri, K3BU, VE3BMV

Incoming signal elevation question
 

On Wed, 17 May 2006 13:30:31 GMT, Cecil Moore
wrote:

Mike Coslo wrote:
It is hard to look at a radiation pattern, conclude that the
take-off angle is the only angle of radiation, and then blame it on
EZNEC!

I knew a ham in Chandler, AZ who would adjust not only
the direction but the height of his beam for maximum signal.
I assume by adjusting the height, he was changing his TOA.


I have heard of many hams stacking beams vertically to get that
earlier signal on one beam, and later in the day, the other beam gets
the stronger signal. Together, they still amplify the signal, but
sometimes one does much better than others at the TOA.


--
73 for now
Buck
N4PGW

Incoming signal elevation question
 

On Wed, 17 May 2006 17:10:00 GMT, Cecil Moore
wrote:

Yuri Blanarovich wrote:
I have seen situations when signals to Europe were coming under low angle
and in the same direction, signals to deep Asia were coming under higher
angle at the same time.

Seems to me a rotatable dipole with the ability to also
rotate from horizontal to vertical would be a good thing
to have.

or tie two together in a vertical/horizontal phased array?
--
73 for now
Buck
N4PGW

Incoming signal elevation question
 

On Wed, 17 May 2006 20:15:24 +0100, "Reg Edwards"
wrote:


How does Eznec know the number of hops? How does Eznec know which
angle is correct? How does Eznec know the height of the reflecting
layers? How does Eznec know the distances at which the radio wave
returns to Earth to be re-reflected?

Eznec doesn't know. And neither does the radio operator unless he
estimates everything AFTER the event.

Radio waves follow paths dictated by trigonometry and geometry and are
entirely independent of the idiosyncrasies of radio antennas.
----
Reg.


Reg, what were you drinking when you wrote this? EZNEC doesn't deal
at all with the atmosphere, it deals with the antenna. If the antenna
has a stronger lobe at 10 degrees in some given direction, EZNEC plots
it, but that doesn't mean the signal will come from that direction.

I have done only a little modeling with the ARRL version and the newer
free one. EZNEC plots the angles of the antenna from a horizontal and
vertical standpoint. Some antennas create single or double, primary
lobes, and others have more primary (highest gain) lobes. However,
when you change the elevation angle that you are watching, those
primary lobes may change to a different angle.

--
73 for now
Buck
N4PGW

Incoming signal elevation question
 

EZNEC knows sh*t about propagation. EZNEC and other antenna modeling
software can calculate the radiation pattern of modeled (not real) antenna
according to given ground parameters and antenna geometry. It gives you idea
how the pattern looks, but not the where the signal goes after entering
propagation media.

However, in collaboration with a propagation prediction program, it
gives you helpfull insights about influence of the pattern on the
propagation and about the take-off angle most likely needed for point
to point contacts on a given day, time and/or frequency. If you don't
mind a little studying, you could try MultiNec, NecWin+ or 4nec2 with
the VOACAP predication software. About EZnec I am not quite sure. To
include terrain influence in all this, you could take a look at HFTA.

Arie.

Incoming signal elevation question
 

An equation that I leave in my HP calculator interrelates the important
parameters.

T = take-of-angle (up from horizon)
D = distance in Mm (40 Mm is all of the way around the earth)
H = virtual height of ionosphere in km

Calculator is using angles in degrees.
Single hop

Cos(T) / Cos(T + 4.5*D) = 1 + H/6366

F2 H for 40 degrees north is between about 250 and 370.

73 Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Ken Bessler" wrote in message
news:VEmag.22577$4H.10017@dukeread03...
Lets assume a single hop 40m signal from 400 miles away. What
elevation angle does it arrive at? Both stations are using inverted V's
at nominal height. There are no large bodies of water in between.

Daytime and/or nighttime.

--
73's de Ken KG0WX -