Spike wrote:
Imagine a short rod vertical aerial not connected to ground, for the
(say) 160/80/60/40m bands, as might be found in a typical /M set-up, fed
with RF energy and operating over ground of average conductivity.

Three different waves will be launched from this: the sky wave, the space
wave (including the reflected ray), and the surface wave. Each of these
have their own characteristics, inasmuch as the sky wave is launched
willy-nilly even if the band isn't open for that mode, the space wave
depends on the path to the receiver, and the surface wave depends on the
electromagnetic characteristics of the air and the surface material,
although to some extent the latter affects all the waves generated.

My question is: since all these result from the emission of RF from the
short rod antenna, what proportions of the total RF power supplied to it
are found in each of these three separate waves, and what factors control
these proportions?

You are Gareth Alun Evans G4SDW AICMFP.

--
STC // M0TEY // twitter.com/ukradioamateur

"Spike" wrote in message
...

Three different waves will be launched from this: the sky wave, the space
wave (including the reflected ray), and the surface wave.

Pace that it might propagate in 3 different modes, but only one wave
is launched.

On 3/6/2015 6:02 PM, Spike wrote:

Imagine a short rod vertical aerial not connected to ground, for the
(say) 160/80/60/40m bands, as might be found in a typical /M set-up, fed
with RF energy and operating over ground of average conductivity.

Three different waves will be launched from this: the sky wave, the
space wave (including the reflected ray), and the surface wave. Each of
these have their own characteristics, inasmuch as the sky wave is
launched willy-nilly even if the band isn't open for that mode, the
space wave depends on the path to the receiver, and the surface wave
depends on the electromagnetic characteristics of the air and the
surface material, although to some extent the latter affects all the
waves generated.

My question is: since all these result from the emission of RF from the
short rod antenna, what proportions of the total RF power supplied to it
are found in each of these three separate waves, and what factors
control these proportions?

I found a reference that says 100% of the signal from an antenna goes
into the sky wave, space wave and the ground wave. None of the signal
is lost in the transmission process after leaving the antenna.

--

Rick

"Spike" wrote in message
...

Imagine a short rod vertical aerial not connected to ground, for the (say)
160/80/60/40m bands, as might be found in a typical /M set-up, fed with RF
energy and operating over ground of average conductivity. (etc)
__________

Below is a link to a NEC study showing the 1.9 MHz fields radiated by a
3-meter vertical monopole driven against 4 x 2-meter horizontal radials,
where the entire assembly is elevated 9" above earth of average
conductivity. This might approximate a mobile installation of a whip
antenna mounted on a vehicle, except for the pattern distortions produced by
the body of the vehicle.

Radiation from this system at elevation angles other than near zero degrees
could act as direct waves, space waves or skywaves, depending on propagation
paths, propagation conditions, and the physical locations of receive
antennas.

http://s20.postimg.org/ipzwlc9kd/Fie...t_Vertical.jpg

R. Fry

On 06/03/15 23:02, Spike wrote:

Imagine a short rod vertical aerial not connected to ground, for the
(say) 160/80/60/40m bands, as might be found in a typical /M set-up, fed
with RF energy and operating over ground of average conductivity.

Many thanks to all who took the trouble to reply, with input ranging
from from the uncouth through the unhelpful to the deeply technical. The
modelling results and the graphs of the surface-wave propagation that
were provided will likely prove very useful for another propagation
project currently under study here.

One fact that has become apparent is that ground conductivity maps that
assign a value to region-wide areas are not to be trusted - there are
sometimes quite severe changes in local conductivity, and these could
encompass the ground that affects the radiation pattern from one's
antenna. However, models have now become sophisticated enough to
incorporate these into their predictions; the difficulty lies in
obtaining reliable conductivity figures for one's location, especially
those of poor conductivity where earth currents can run deep in the
soil. Although this isn't strictly an 'antenna' issue, it is
nevertheless fundamental to LF/MF/HF operation and highly pertinent as
to how the antenna contributes to the station performance.

--
Spike

"Hard cases, it has frequently been observed, are apt to introduce bad
law". Judge Rolfe

Spike wrote:
On 06/03/15 23:02, Spike wrote:

Imagine a short rod vertical aerial not connected to ground, for the
(say) 160/80/60/40m bands, as might be found in a typical /M set-up, fed
with RF energy and operating over ground of average conductivity.

Many thanks to all who took the trouble to reply, with input ranging from
from the uncouth through the unhelpful to the deeply technical. The
modelling results and the graphs of the surface-wave propagation that
were provided will likely prove very useful for another propagation
project currently under study here.

One fact that has become apparent is that ground conductivity maps that
assign a value to region-wide areas are not to be trusted - there are
sometimes quite severe changes in local conductivity, and these could
encompass the ground that affects the radiation pattern from one's
antenna. However, models have now become sophisticated enough to
incorporate these into their predictions; the difficulty lies in
obtaining reliable conductivity figures for one's location, especially
those of poor conductivity where earth currents can run deep in the soil.
Although this isn't strictly an 'antenna' issue, it is nevertheless
fundamental to LF/MF/HF operation and highly pertinent as to how the
antenna contributes to the station performance.


While your local earth conductivity may well vary from that for you region,
in the scheme of things, especially if the path in question includes a
transit of sea water, to suggest it will play a significant role is
somewhat bold. To see this, look at the relative numbers I gave earlier for
North America.

Local conditions will, of course, impact antenna efficiency.

I suggest you do some more thinking before you challenge the work of the
eminent people who have studied this area and published papers etc.

On 12/03/15 13:28, Brian Reay wrote:
Spike wrote:
On 06/03/15 23:02, Spike wrote:

Imagine a short rod vertical aerial not connected to ground, for the
(say) 160/80/60/40m bands, as might be found in a typical /M set-up, fed
with RF energy and operating over ground of average conductivity.

Many thanks to all who took the trouble to reply, with input ranging from
from the uncouth through the unhelpful to the deeply technical. The
modelling results and the graphs of the surface-wave propagation that
were provided will likely prove very useful for another propagation
project currently under study here.

One fact that has become apparent is that ground conductivity maps that
assign a value to region-wide areas are not to be trusted - there are
sometimes quite severe changes in local conductivity, and these could
encompass the ground that affects the radiation pattern from one's
antenna. However, models have now become sophisticated enough to
incorporate these into their predictions; the difficulty lies in
obtaining reliable conductivity figures for one's location, especially
those of poor conductivity where earth currents can run deep in the soil.
Although this isn't strictly an 'antenna' issue, it is nevertheless
fundamental to LF/MF/HF operation and highly pertinent as to how the
antenna contributes to the station performance.

While your local earth conductivity may well vary from that for you region,
in the scheme of things, especially if the path in question includes a
transit of sea water, to suggest it will play a significant role is
somewhat bold. To see this, look at the relative numbers I gave earlier for
North America.

If you understand what I wrote above, you'll see my point was about
local conductivity and how it affects the radiation pattern after being
launched from an antenna, rather than the variability along a signal
path, although I did mention for completeness that models can now take
such variability into account.

Local conditions will, of course, impact antenna efficiency.

The antenna efficiency is affected by its mechanical form. Earth losses
are something else, which can be factored in to estimate antenna system
efficiency, which, of course, isn't the same thing.

I suggest you do some more thinking before you challenge the work of
eminent people who have studied this area and published papers etc.

I asked a simple and straightforward question, which has been answered
only in part and not at all by you, in what appears to be your normal
spirit of offering every assistance short of actual help. As you mention
published papers, perhaps you'd let us know how many of yours have seen
the light of day in peer-reviewed prestige journals?

I find it difficult to accept input on this and similar matters from
someone who not only avoided taking out an HF licence for 30 years but
who also judges the finer points of HF receiver performance by noting
which DXpeditions might be subsidised by which manufacturer.


--
Spike

"Hard cases, it has frequently been observed, are apt to introduce bad
law". Judge Rolfe

On 12/03/15 18:43, Spike wrote:
On 12/03/15 13:28, Brian Reay wrote:
Spike wrote:
On 06/03/15 23:02, Spike wrote:

Imagine a short rod vertical aerial not connected to ground, for the
(say) 160/80/60/40m bands, as might be found in a typical /M set-up,
fed
with RF energy and operating over ground of average conductivity.

Many thanks to all who took the trouble to reply, with input ranging
from
from the uncouth through the unhelpful to the deeply technical. The
modelling results and the graphs of the surface-wave propagation that
were provided will likely prove very useful for another propagation
project currently under study here.

One fact that has become apparent is that ground conductivity maps that
assign a value to region-wide areas are not to be trusted - there are
sometimes quite severe changes in local conductivity, and these could
encompass the ground that affects the radiation pattern from one's
antenna. However, models have now become sophisticated enough to
incorporate these into their predictions; the difficulty lies in
obtaining reliable conductivity figures for one's location, especially
those of poor conductivity where earth currents can run deep in the
soil.
Although this isn't strictly an 'antenna' issue, it is nevertheless
fundamental to LF/MF/HF operation and highly pertinent as to how the
antenna contributes to the station performance.

While your local earth conductivity may well vary from that for you
region,
in the scheme of things, especially if the path in question includes a
transit of sea water, to suggest it will play a significant role is
somewhat bold. To see this, look at the relative numbers I gave
earlier for
North America.

If you understand what I wrote above, you'll see my point was about
local conductivity and how it affects the radiation pattern after being
launched from an antenna, rather than the variability along a signal
path, although I did mention for completeness that models can now take
such variability into account.

Local conditions will, of course, impact antenna efficiency.

The antenna efficiency is affected by its mechanical form. Earth losses
are something else, which can be factored in to estimate antenna system
efficiency, which, of course, isn't the same thing.

I suggest you do some more thinking before you challenge the work of
eminent people who have studied this area and published papers etc.

I asked a simple and straightforward question, which has been answered
only in part and not at all by you, in what appears to be your normal
spirit of offering every assistance short of actual help. As you mention
published papers, perhaps you'd let us know how many of yours have seen
the light of day in peer-reviewed prestige journals?

I find it difficult to accept input on this and similar matters from
someone who not only avoided taking out an HF licence for 30 years but
who also judges the finer points of HF receiver performance by noting
which DXpeditions might be subsidised by which manufacturer.




As ever, by you inaccurate closing paragraphs you've shown yourself to
be an foolish troll, like your friend Evans. I suggest that, to save
yourself further embarrassment, you revert to your normal habit of
avoiding the technical groups and revert to your role of telling fantasy
stories about your past.

On 12/03/15 19:54, Brian Reay wrote:
On 12/03/15 18:43, Spike wrote:

I find it difficult to accept input on this and similar matters from
someone who not only avoided taking out an HF licence for 30 years but
who also judges the finer points of HF receiver performance by noting
which DXpeditions might be subsidised by which manufacturer.

As ever, by you inaccurate closing paragraphs you've shown yourself to
be an foolish troll, like your friend Evans. I suggest that, to save
yourself further embarrassment, you revert to your normal habit of
avoiding the technical groups and revert to your role of telling fantasy
stories about your past.

I note that when you have no technical input to a thread, you resort to
insults and bluster. They didn't take long to find you out in the Ubuntu
group, and I suspect this one is no different. No wonder you're in my
Trolls filter over in UKRA.

I've just posted a 'story about my past' in response to Jeff. Enjoy.


--
Spike

"Hard cases, it has frequently been observed, are apt to introduce bad
law". Judge Rolfe

Brian Reay wrote:
On 12/03/15 18:43, Spike wrote:
On 12/03/15 13:28, Brian Reay wrote:
Spike wrote:
On 06/03/15 23:02, Spike wrote:

Imagine a short rod vertical aerial not connected to ground, for the
(say) 160/80/60/40m bands, as might be found in a typical /M set-up,
fed
with RF energy and operating over ground of average conductivity.

Many thanks to all who took the trouble to reply, with input ranging
from
from the uncouth through the unhelpful to the deeply technical. The
modelling results and the graphs of the surface-wave propagation that
were provided will likely prove very useful for another propagation
project currently under study here.

One fact that has become apparent is that ground conductivity maps that
assign a value to region-wide areas are not to be trusted - there are
sometimes quite severe changes in local conductivity, and these could
encompass the ground that affects the radiation pattern from one's
antenna. However, models have now become sophisticated enough to
incorporate these into their predictions; the difficulty lies in
obtaining reliable conductivity figures for one's location, especially
those of poor conductivity where earth currents can run deep in the
soil.
Although this isn't strictly an 'antenna' issue, it is nevertheless
fundamental to LF/MF/HF operation and highly pertinent as to how the
antenna contributes to the station performance.

While your local earth conductivity may well vary from that for you
region,
in the scheme of things, especially if the path in question includes a
transit of sea water, to suggest it will play a significant role is
somewhat bold. To see this, look at the relative numbers I gave
earlier for
North America.

If you understand what I wrote above, you'll see my point was about
local conductivity and how it affects the radiation pattern after being
launched from an antenna, rather than the variability along a signal
path, although I did mention for completeness that models can now take
such variability into account.

Local conditions will, of course, impact antenna efficiency.

The antenna efficiency is affected by its mechanical form. Earth losses
are something else, which can be factored in to estimate antenna system
efficiency, which, of course, isn't the same thing.

I suggest you do some more thinking before you challenge the work of
eminent people who have studied this area and published papers etc.

I asked a simple and straightforward question, which has been answered
only in part and not at all by you, in what appears to be your normal
spirit of offering every assistance short of actual help. As you mention
published papers, perhaps you'd let us know how many of yours have seen
the light of day in peer-reviewed prestige journals?

I find it difficult to accept input on this and similar matters from
someone who not only avoided taking out an HF licence for 30 years but
who also judges the finer points of HF receiver performance by noting
which DXpeditions might be subsidised by which manufacturer.




As ever, by you inaccurate closing paragraphs you've shown yourself to
be an foolish troll, like your friend Evans. I suggest that, to save
yourself further embarrassment, you revert to your normal habit of
avoiding the technical groups and revert to your role of telling fantasy
stories about your past.

This hasn't been a total waste of time, Brian, I haven't laughed this hard
all week!

--
STC // M0TEY // twitter.com/ukradioamateur