"Roy Lewallen" wrote in message
...
I sense there's still a failure to communicate.

If Dale means by "V/U" VHF and UHF, ground wave isn't a viable means of
propagation anyway. The attenuation of ground waves increases with
frequency, to the point that they're virtually useless at VHF and above.
So at those frequencies, I'd think the polarization choice for short
range communication would be based on how it affects attenuation,
multipath, and QRM. Given those criteria, horizontal might well have an
advantage for short range communication, in some locations at least. And
it's long been favored for long range VHF/UHF communication.


Ground wave is a broad term, but it is how VHF and UHF usually propagate.
Ground wave is a general term for several means of propagation. Surface
wave is what you are really talking about when you mention Ground wave.
Space wave, atmosphere ducts and other means near the earth are all part of
the Ground wave term. The Sky wave is usually the broad term for
reflections off the ionosphere and other reflected modes from high above the
surface.

For vertical or horizontal there is very little differance in which is used
at VHF and above. Noise is usually vertical polorised so horizontal for the
RF is usually used . Vertical is used so the simple vertical moble whips
could be used for all around coverage.

Ian White, G3SEK wrote:
So what does the IEEE define a "Norton surface wave" to be?

"Norton surface wave - a guided EM wave produced by a source
over or on the ground. It is the non-geometrical optics
component of the ground wave."

"geometric optics - the treatment of propagation of light as
rays. Note: Rays are bent at the interface between two dissimilar
media or may be curved in a medium in which refractive index is a
function of position."

Presumably, there are no geometric optics involved in RF emissions
from an antenna. Therefore, for an RF antenna, the Norton wave
equals the surface wave. The surface wave and ground wave are
NOT the same thing. Besides the surface wave, the ground wave
contains part of the space wave which itself consists of two
parts, direct and ground-reflected.

So according to the IEEE, it is not ground wave Vs sky wave.
It is surface wave Vs sky wave. Ground wave = part surface
wave and part sky wave.
--
73, Cecil http://www.qsl.net/w5dxp


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Andrey wrote:
"I want to create horizontally polarized antenna, low profile, located
above large ground plane. And I need it to be omnidirectional (sort of)
and have sufficient gain in horizontal plane.

My frequency of interest is 900 MHz. The ground plane is a roof of a
car."

A horizontal dipole above a metal car roof is a poor choice.

Polarization choice at 900 MHz does not affect signal range.

In the horizontal plane, the direct signal broadside to the dipole is
cancelled by the reflected signal from the roof unless you elevate the
dipole by 50 cm or so at 900 MHz. That`s almost 2 wavelengths. At that
height, the omnidirectionality may not be even "sort of".

Better to use a vertical which has a signal null off its tip and maximum
radiation in the horizontal plane. This can be a collinear made of
1/2-wave sections separated by 1/4-wave stub(s) for gain. As the
wavelength is only 34 centimeters, this isn`t much of a problem. It
could be made by bending a single length of stiff wire.

Best regards, Richard Harrison, KB5WZI

Thanks to all who responded. I see I've been misusing "ground wave" for
a long time, in place of "surface wave". And my apology to those I've
questioned about "ground wave" propagation at VHF/UHF. According to
correct usage, it does indeed exist -- just not with a surface wave
component.

Roy Lewallen, W7EL

Hi Dale,

Are you saying that the old saturn halo was not 3 loops? It sure looks like it
in the pictures that I have seen.

I know that your design (the Par Omniangle) is not the classic 1/2 wave halo,
and does offer more advantages over a halo. I sure wish I had a 2m and 6m for
the upcoming VHF contest.

Randy ka4nma

Roy Lewallen wrote:
Thanks to all who responded. I see I've been misusing "ground wave" for
a long time, in place of "surface wave". And my apology to those I've
questioned about "ground wave" propagation at VHF/UHF. According to
correct usage, it does indeed exist -- just not with a surface wave
component.

Likewise, my apologies to anyone whom I've misled.

But I apologise with fingers crossed behind my back!

The IEEE Dictionary mavens have produced a very HF-centric definition of
"ground wave", by defining it to include all modes of propagation except
"sky wave"; where "sky" is exclusively defined as "ionospheric".

This definition completely ignores all the non-ionospheric VHF/UHF
propagation modes that don't involve the ground at all.

Since a misleading definition is worse than no definition at all, the
best policy for the term "ground wave" is to label it "Broken - Do Not
Use".


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Ian, G3SEK wrote:
"The IEEE Dictionary mavens have produced a very HF-cebtric definition
of "ground wave"."

Regretable. Seems clear that a ground wave would require interaction
with the ground. According to Terman it does. On page 803 of his 1955
edition, Terman says:

"The "ground wave" (also sometimes called surface wave) can exist when
the transmitting and receiving antennas are close to the surface of the
earth and are vertically polarized. This wave, supported at its lower
edge by the presence of the ground, is of practical importance at
broadcast and lower frequencies."

The ground wave requires the earth to participate in its propagation and
the earth gives the ground wave a continuation beyond the line-of-sight
without atmospheric or ionospheric intervention.

Best regards, Richard Harrison, KB5WZI

Ian White, G3SEK wrote:
The IEEE Dictionary mavens have produced a very HF-centric definition of
"ground wave", by defining it to include all modes of propagation except
"sky wave"; where "sky" is exclusively defined as "ionospheric".

"sky wave - a radio wave propagated obliquely toward, and returned from,
the ionosphere."

Apparently, if it's not returned from the ionosphere, it's not a
sky wave. That implies that the stars are not in the sky. :-)
--
73, Cecil http://www.qsl.net/w5dxp



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