In 21.36 06/02/00 , Vaino OH2LX wrote:
Some thoughts on 136 kHz Ionospheric propagation
Sorry for this not being in phase with T/A ideas.
On the practicability of talking about "hops"
Suggested experiment: Draw a circle with a radius
of 63.70 cm. Then draw a slightly bigger circle
with radius of 64.50 cm, using same center point.
With a reflection height of some 80 to 90 km the
space between the concentric circles is small..?
Pictures are 99% drawn to a completely wrong scale.
Might be better talk abt "bends" instead of "hops".
Not all active hams are interested on this kind
of digging into propagation details. For those who
are, I'll be glad to calculate selected paths etc.
please, continue your 'digging'. If our main objective
in this fantastic hobby is self-instruction, we must
have somebody teaching and helping us to remain with
feet on Earth, even looking at the ionosphere ... ;-)
May be true that not all active hams are interested; but I
firmly believe that the main scope of this reflector is to
put hams with similar interests in touch, and many of us
must be concerned about wave propagation, to make
better QSO or simply to try to understand.
Your suggested experiment is very clear. In effect we are
used to figure the ionospheric layers as an high ceiling;
compared with the earth radius it is very low.
I have a question for antenna modelling gurus (G3LDO?)
What is the vertical radiation pattern of our shortened
verticals? Is it dependent of ground resistance and nearby
objects? may we model it?
Marco Bruno - IK1ODO
SPIN Electronics - www.spin-it.com