Wow the more this thread goes the deeper the s**t gets,
the first poster has no chance,,
reminds me of a pig wrestling contest, you jump in and all you do is get is
full of mud and s**t.
Im heading down to the beach and going to holler real loud, see if any of
you guys in CA can hear my flooding of the atmosphere with my LF waves
Theres a hurricane on the way so it may deflect the waves some, so bear
with me it may take a few times of HALLO to get through..
Let me get my tin hat out also..
73 Merv K9FD/KH6
Modeling programs are an excellent tool to calculate and predict some
properties of antennas - radiators.
What they do not "see" is the propagation mechanism after RF leaves
the antenna. "Space wave" can be "hugging wave".
While the high frequencies signals behave more like high frequency
sounds - propagating in the straight line, hitting the ionosphere and
then reflecting or refracting and continuing on.
Lower frequencies tend to propagate similarly as low frequency sounds
- "flooding" the medium. On 160 and 80 we see signals "flooding" the
medium with hardly any dead spots or zones, except some long haul
path, where some focusing and ducting comes to play. I tried to
elaborate on ways we propagate on HF in my article
http://www.k3bu.us/propagation.htm
I have observed that, say on 160 low angle signals, such as produced
by the salt water locations, seem to "hug" the Earth surface
curvature, appears to be ducting, refracting, rather than "bouncing"
off the ionosphere. We know that low band signals are
"flooding", refracting, ducting, signals without dead zones, unlike we
do experience propagation on high bands.
Polarization, its rotation in media, is another factor that modeling
doesn't capture.
Long haul and focusing is on the mercy of propagation conditions.
We have to look at the antenna (radiator, radials, etc.) as RF source,
analogous to light bulb.
Environment, ground conditions, surroundings, analogous to mirror(s)
affecting, participating in the beam shaping and efficiency of the
antenna. Modeling is an excellent tool for that.
Propagating media, air, ionosphere, as a "wire" carrying our signals.
Propagation modeling can do some help here.
Tailoring each of those factors and variables for the best fit gets
best results.
Then we have long delayed echoes that make us wonder what is going on.
I keep wondering if Earth - air - ionosphere - VanAllen belts - space
is some kind of giant vacuum tube or resonator that enhances RF signals?
Tesla calculated the capacitance and self resonant frequency of Earth....
73 Yuri, K3BU.us
On Wed, Aug 13, 2014 at 09:34 AM, Richard Fry wrote:
> The link in the opening post of this thread shows an interesting,
animated analysis of the elevation gains of a monopole, based on a NEC
far-field analysis not including the surface wave.
I then posted this comment, "Reality is that radiation leaving the
monopole at elevation angles of at least 5 degrees decays at a 1/r
rate. Therefore that radiation is a space wave which propagates in a
~ straight line to reach the ionosphere, where (with suitable
conditions) it can return to the earth as a skywave."
Others have been skeptical that this low-angle radiation was a space
wave that could reach the ionosphere.
Recently I investigated this more closely, leading to the NEC4.2
study linked below. It shows that the 3.8 MHz radiation existing on
a departure angle of 5 degrees at a distance of 3/10 of a mile from a
monopole continues on toward the ionosphere along that path, while
its value decays at a 1/r rate -- indicating that it is a space wave.
http://s20.postimg.org/6yau4m225/Monopole_Radiation_5_deg_Departure.jpg
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