"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