Check out the HAM transmission records from Hawaii to the mainland.
Impressive.




"Vito" wrote in message
...
Wally wrote:

Bobsprit claims to have made a VHF transmission of over 40nm. ...
Would anyone care to comment on the veracity of Bobsprit's claim?


When it comes to radio, I've seen too many things that can't happen
actually occur that I'd never, ever doubt a report based on technical
improbability. Eg,I was monitoring a 2-meter (147 MHz) ham repeater here
in VA awhile back when a local QSO from Argentina came booming into my
handheld. Of course they couldn't hear me but the real oddity is that
other hams monitoring the same freq just a few miles away never heard
them!

No, it's less attenuation in its normal mode of propagation. It has to do
with the decompression of the magnetosphere on the side of the earth away
from the sun..

Almost all AM radio stations transmit in the vertical polarization, the
antenna beam launch angle is low, it's difficult to get skip.

Horizontal polarized antennas (spaced properly above a ground plane) have a
launch angle that is favorable for skip.

If it was skip, there would be regions of no reception between regions of
reception. AM radio is continuous reception until it just fades out.

You can get AM wavelengths to skip, but it is not as common as in other
shorter wavelengths.

Henriech Hertz


"Horvath" wrote in message
...
On Thu, 04 Sep 2003 02:26:05 GMT, "Flounder" wrote
this crap:

AM (600-1600 KHz) is a ground wave. It doesn't skip.

It travels further at night because the ionic concentrations in the
Appleton
layer decrease from lack of sunlight and the solar wind.

Well gee, that's a skip, isn't it?




Ave Imperator Bush!
Bush Was Right! Four More Years!

So, can you explain tropo scatter?
krj

Flounder wrote:
No, it's less attenuation in its normal mode of propagation. It has to do
with the decompression of the magnetosphere on the side of the earth away
from the sun..

Almost all AM radio stations transmit in the vertical polarization, the
antenna beam launch angle is low, it's difficult to get skip.

Horizontal polarized antennas (spaced properly above a ground plane) have a
launch angle that is favorable for skip.

If it was skip, there would be regions of no reception between regions of
reception. AM radio is continuous reception until it just fades out.

You can get AM wavelengths to skip, but it is not as common as in other
shorter wavelengths.

Henriech Hertz


"Horvath" wrote in message
...

On Thu, 04 Sep 2003 02:26:05 GMT, "Flounder" wrote
this crap:


AM (600-1600 KHz) is a ground wave. It doesn't skip.

It travels further at night because the ionic concentrations in the

Appleton

layer decrease from lack of sunlight and the solar wind.

Well gee, that's a skip, isn't it?




Ave Imperator Bush!
Bush Was Right! Four More Years!

As in tropo scatter radar? Communication? Sensing? Profiling?


"Kelton Joyner" wrote in message
...
So, can you explain tropo scatter?
krj

Flounder wrote:
No, it's less attenuation in its normal mode of propagation. It has to
do
with the decompression of the magnetosphere on the side of the earth
away
from the sun..

Almost all AM radio stations transmit in the vertical polarization, the
antenna beam launch angle is low, it's difficult to get skip.

Horizontal polarized antennas (spaced properly above a ground plane)
have a
launch angle that is favorable for skip.

If it was skip, there would be regions of no reception between regions
of
reception. AM radio is continuous reception until it just fades out.

You can get AM wavelengths to skip, but it is not as common as in other
shorter wavelengths.

Henriech Hertz


"Horvath" wrote in message
...

On Thu, 04 Sep 2003 02:26:05 GMT, "Flounder" wrote
this crap:


AM (600-1600 KHz) is a ground wave. It doesn't skip.

It travels further at night because the ionic concentrations in the

Appleton

layer decrease from lack of sunlight and the solar wind.

Well gee, that's a skip, isn't it?




Ave Imperator Bush!
Bush Was Right! Four More Years!

There's a layer of air on the surface of the water that has a difference in
temperature in the air above it. The permitivitty (index of refraction) of
the two layers of air are different. The difference is in the thousandth
decimal place. Because of the difference in the permitivitty a radio wave
striking the upper layer at or below the Brewster angle experiences total
internal reflection. The wave becomes trapped between the water and the
second air layer. Part of the wave does travel in the second layer, at the
boundary. That is the evanescent wave. That is also the type of wave that
allows your prism binoculars to work. The wave also travels at two different
velocities in the two air layers.
So, looking at the transmitting antenna as an isotropic radiator at 150 MHz,
the layer height at 30 meters how many modes propagate on the sea surface?

"The Captains Master" wrote in message
news
\
Umm yeah, but I asked if YOU could explain it in English.
I didn't want a direction to the webpage you used to get the stuff you
don't understand either.


On Thu, 04 Sep 2003 13:10:34 GMT, "Flounder"
wrote:


www.physics.gatech.edu/gcuo/UltrafastOptics/ PhysicalOptics/Class08.ppt


"The Captains Master" wrote in message
.. .
On Wed, 03 Sep 2003 19:43:38 GMT, "Flounder"
wrote:

Evanescent surface wave at the Brewster angle.

WTF, you wanna try that in English!......if you can.....


Oz1...of the 3 twins.
I welcome you to crackerbox palace,We've been expecting you.






Oz1...of the 3 twins.
I welcome you to crackerbox palace,We've been expecting you.

"Flounder" wrote in message
ink.net...
There's a layer of air on the surface of the water that has a difference
in
temperature in the air above it. The permitivitty (index of refraction) of
the two layers of air are different. The difference is in the thousandth
decimal place. Because of the difference in the permitivitty a radio wave
striking the upper layer at or below the Brewster angle experiences total
internal reflection. The wave becomes trapped between the water and the
second air layer. Part of the wave does travel in the second layer, at the
boundary. That is the evanescent wave. That is also the type of wave that
allows your prism binoculars to work. The wave also travels at two
different
velocities in the two air layers.
So, looking at the transmitting antenna as an isotropic radiator at 150
MHz,
the layer height at 30 meters how many modes propagate on the sea surface?


You call *that* an explanation??

BTW, these "modes" that you refer to, - are they in any way similiar to the
"modes" in fibre optic transmission systems? They sound like they might be.

If they are, I would be very interested is a *plain* English explanation!
I really should know the difference between multi- and single-mode fibre
optics.

BTW this isn't a trick question. I'm genuinely interested.



Regards


Donal
--

On Thu, 04 Sep 2003 02:26:05 GMT, "Flounder" wrote
this crap:

AM (600-1600 KHz) is a ground wave. It doesn't skip.

With the proper antenna, such as a dipolar, it will.




Ave Imperator Bush!
Bush Was Right! Four More Years!

Absolutely the same thing as modes in a fibre optic cable. Except cables are
cylindrical (field solutions described by Bessel functions) and the
water-air geometry is described by some form of Hankel functions.

Single mode fibres are very thin. The thick cables have very many modes, all
traveling with different phase velocities and distorting pulses over the
length of the cable. Single mode fibres propagate only one mode and the
pulse retains its shape over very long distances.

The fibre optic cables act as waveguides. If the diameter of the cable is
too small (about less than 1/2 wavelength) a wave will not propagate in the
cable. If the diameter is greater than about 1/2 wavelength up to roughly .6
wavelengths then the first mode propagates called the HE11 mode. A little
larger diameter propagates the HE11 and the TE01 modes. As you increase the
diameter the number of modes increases. There's also degenerate modes,
hybrid modes, transverse electric and magnetic modes. It gets fairly
complex. There's a formula used to calculate the number of modes in big
fibres. This is all for stepped index fibres.

Fibre cables are clad to keep dust of the cable. The dust disturbs the
evanascent modes on the outside of the cable (kills the signal) just like
dirty prisms cause binoculars to work poorly.

Feel free to ask more questions, I can use the review.



"Donal" wrote in message
...

"Flounder" wrote in message
ink.net...
There's a layer of air on the surface of the water that has a difference
in
temperature in the air above it. The permitivitty (index of refraction)
of
the two layers of air are different. The difference is in the thousandth
decimal place. Because of the difference in the permitivitty a radio
wave
striking the upper layer at or below the Brewster angle experiences
total
internal reflection. The wave becomes trapped between the water and the
second air layer. Part of the wave does travel in the second layer, at
the
boundary. That is the evanescent wave. That is also the type of wave
that
allows your prism binoculars to work. The wave also travels at two
different
velocities in the two air layers.
So, looking at the transmitting antenna as an isotropic radiator at 150
MHz,
the layer height at 30 meters how many modes propagate on the sea
surface?


You call *that* an explanation??

BTW, these "modes" that you refer to, - are they in any way similiar to
the
"modes" in fibre optic transmission systems? They sound like they might
be.

If they are, I would be very interested is a *plain* English explanation!
I really should know the difference between multi- and single-mode fibre
optics.

BTW this isn't a trick question. I'm genuinely interested.



Regards


Donal
--

On Thu, 04 Sep 2003 13:20:03 GMT, "Flounder" wrote
this crap:

No, it's less attenuation in its normal mode of propagation. It has to do
with the decompression of the magnetosphere on the side of the earth away
from the sun..

Actually it's the ionosphere,

Almost all AM radio stations transmit in the vertical polarization, the
antenna beam launch angle is low, it's difficult to get skip.

Were we talking about commercial AM radio? I thought we were talking
about SSB.




Ave Imperator Bush!
Bush Was Right! Four More Years!

Horvath wrote in :

On Thu, 04 Sep 2003 02:26:05 GMT, "Flounder" wrote
this crap:

AM (600-1600 KHz) is a ground wave. It doesn't skip.

With the proper antenna, such as a dipolar, it will.


So that explains why you can get radio in your head so well.


Bertie