E/M radiation from a short vertical aerial
 

Roger Hayter wrote:
Stephen Thomas Cole wrote:

Roger Hayter wrote:
Stephen Thomas Cole wrote:

rickman wrote:
On 3/8/2015 4:17 PM, Stephen Thomas Cole wrote:

Spike, you're a gormless ****. Seriously, you're giving Gareth Alun Evans
G4SDW a run for his money here.

I can see you are right in the running yourself...

Hey, I'm not the one with the fundamental misunderstanding of radio theory
after 50+ years in the hobby.

There is no "fundamental misunderstanding" unless it be yours. At
worst, loose phraseology.


I suggest you re-read Spike's multiple, confused posts about all the
different types of waves that pour forth from an antenna.

I have. Your comprehension of common expressions is lacking. Some of
the Americans pedantically criticised his description, but I think we
have all come round to knowing what he meant now, and that disagreement
has been resolved. You seem to want to repeat it just to be abusive
rather than to contribute to the discussion.

Tosh. Spike posted gibberish, several times, and was quite rightly
corrected for it. His subsequent petulance about being put right is the
icing on the cake. He's done a Gareth.

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

E/M radiation from a short vertical aerial
 

On 3/9/2015 12:54 PM, Brian Reay wrote:
On 09/03/15 15:43, Jerry Stuckle wrote:
On 3/9/2015 10:11 AM, Jeff wrote:


As are basically all formulas. Even Ohm's Law was derived from actual
observations.


That is certainly not correct in a lot of cases. The inverse square law
for free space path loss, for example, is derived intuitively and simply
from the transmitted power being equally distributed in all directions,
not from observations.

S= P*(1/(4piD^2))

Jeff

Jeff,

Actually, not. It was observed first back in the 1700's-1800's when the
link between electricity and magnetism was being investigated. And
hundreds of years before that, it was a know property of magnets.

The equations didn't come until later.


You are confusing a magnetic field with an EM field. You can have a
magnetic field with no E field- eg from a bar magnet. It will have a
magnet field which exhibits the inverse square law but no E field.

The problem would seem to be that there is confusion with an equation
being preceded by measurements (pretty much *every* equation known) with
equations that were crafted in the absence of derivation solely to fit
data. Even Einstein's equations had measurements that preceded them and
were essential to their formulation. Michelson and Morley made the
measurements that set the stage for E=Mc^2. I would hardly call that an
empirical equation.

Not much point in trying to discuss this. It will be impossible to find
any common ground I am sure.

--

Rick

E/M radiation from a short vertical aerial
 

On 3/9/2015 1:08 PM, Charlie wrote:
On Sun, 08 Mar 2015 20:03:20 -0400, rickman wrote:

I can see you are right in the running yourself...

This always seem to happen - an interesting and informative thread gets
hijacked and abused by ignorant trolls.

I apologize. Sometimes I think I am trying to do some good, but there
is no point in trying to teach pigs to sing. I'll stop feeding the trolls.

--

Rick

E/M radiation from a short vertical aerial
 

rickman wrote:

On 3/9/2015 12:54 PM, Brian Reay wrote:
On 09/03/15 15:43, Jerry Stuckle wrote:
On 3/9/2015 10:11 AM, Jeff wrote:


As are basically all formulas. Even Ohm's Law was derived from actual
observations.


That is certainly not correct in a lot of cases. The inverse square law
for free space path loss, for example, is derived intuitively and simply
from the transmitted power being equally distributed in all directions,
not from observations.

S= P*(1/(4piD^2))

Jeff

Jeff,

Actually, not. It was observed first back in the 1700's-1800's when the
link between electricity and magnetism was being investigated. And
hundreds of years before that, it was a know property of magnets.

The equations didn't come until later.


You are confusing a magnetic field with an EM field. You can have a
magnetic field with no E field- eg from a bar magnet. It will have a
magnet field which exhibits the inverse square law but no E field.

The problem would seem to be that there is confusion with an equation
being preceded by measurements (pretty much *every* equation known) with
equations that were crafted in the absence of derivation solely to fit
data. Even Einstein's equations had measurements that preceded them and
were essential to their formulation. Michelson and Morley made the
measurements that set the stage for E=Mc^2. I would hardly call that an
empirical equation.

Not much point in trying to discuss this. It will be impossible to find
any common ground I am sure.

OK, lets not treat it as aerial question. Though this is an aerial
group, I would have thought propagation was on topic. Can I ask if
there is any information around which would give us some guidance on
what power one would need in a dampish country about 200 by 800 miles
across to intercommunicate by ground wave at 1.8MHZ? I think this is
actually the gist of Spike's question, assuming everyone uses decent
vertical aerials (a big assumption, of course).

--
Roger Hayter

E/M radiation from a short vertical aerial
 

Roger Hayter wrote:

snip

OK, lets not treat it as aerial question. Though this is an aerial
group, I would have thought propagation was on topic. Can I ask if
there is any information around which would give us some guidance on
what power one would need in a dampish country about 200 by 800 miles
across to intercommunicate by ground wave at 1.8MHZ? I think this is
actually the gist of Spike's question, assuming everyone uses decent
vertical aerials (a big assumption, of course).

http://www.itu.int/rec/R-REC-P.368/en

Follow the link to the latest version, language, and format desired.

Covers the frequency range of 10 kHz to 30 MHz.


--
Jim Pennino

E/M radiation from a short vertical aerial
 

On 09/03/15 17:10, Charlie wrote:
On Mon, 09 Mar 2015 13:10:00 +0000, Brian Reay wrote:

Nor do you spend your time putting done newcomer

Here we go - sigh, another group you have to be plonked from.. Please
give it rest.

TIA.


Well, if that were true, it would cut down your abuse. Sadly, we all
know it isn't true and you will continue your silly interjections.

Now run along and play in your fantasy village, you can probably play
your silly games there and make believe someone cares.

E/M radiation from a short vertical aerial
 

On Monday, March 9, 2015 at 4:12:45 AM UTC-5, Spike wrote:

That's space wave on 10m.

Not in the UK! Even the flatlands of Norfolk and Lincolnshire have
enough surface topography to make space-wave unlikely.

It's very unlikely to be surface wave at that frequency.
If they are able to communicate over that land on 10m, they almost
surely are using the space wave.
If not purely direct within the normal radio horizon, by refraction or
reflection or both. And you are not stating how high the antennas are
mounted, which would be a large factor also.
I hope you are not trying to tell me that no one in that area can
receive any VHF or UHF TV or radio transmissions.. :/



Well, not everyone does. I know many on 160m who favor verticals.
Not only for ground wave, but better DX.

Not in the UK... We have a progressive licensing system here, in which
most people never progress at all. The level they qualify at is more
concerned with how to fit mains plugs - something that isn't required
here as moulded plugs have been compulsory for 20 years. These people
tend to buy the one aerial they've heard of, the G5RV.

I'm fairly sure not everyone in the UK depends solely on the GR5V as a
160m antenna. :/


The ground wave is pretty good on 160m if using a vertical.
Nearly as good as on the MW AM broadcast band, being the two bands
are right next door to each other, so to speak.

I'm a big fan of 160m ground wave/surface wave.

It can be handy. I like listening to AM broadcast in the daytime which
at any real distance is surface wave. One thing that is handy about it,
is you can often totally null it out to receive stations on the same
frequency, but in different directions if using a small loop, etc..
I've made a few recordings which I posted here in the past demonstrating
that. I could make most AM-BC stations via surface wave flat out vanish
if I felt so compelled. :) And then another one would be listenable in
it's place. With a wire or vertical, it would just be a jumble of two
or more stations all being received at once.

E/M radiation from a short vertical aerial
 

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

E/M radiation from a short vertical aerial
 

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.

E/M radiation from a short vertical aerial
 

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