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radiation patterns of different types of antennas

freecell said:
"Groundwave propagation on 11 meters???? REALLY?"

GROUND-WAVE PROPAGATION CURVES FOR FREQUENCIES
BETWEEN 10 kHz AND 30 MHz. over 11 different types of signal-path soil conditions.

the propagation curves in this recommendation are calculated based on the assumption that both the transmitting and the receiving antennas are at ground level.

http://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.368-8-200503-S!!PDF-E.pdf
Click to expand...


The BIG problem is that probably 99.999% of CBers and a significant % of amateurs do not use the term "ground wave" properly. True ground wave does NOT exist at 30 MHz and dies off rapidly above 3 MHz, yes three megahertz. It's another one of those things I got tired of repeating as it is like yelling in a vacuum.

They think that if it is not sky wave propagation, then it is ground wave propagation.
 
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The BIG problem is that probably 99.999% of CBers and a significant % of amateurs have been told in various publications over the years that ground or surface wave propagation @ both 10 and 11 meters is impossible at distances beyond 6 - 7 statute miles or 10 kM.. this is clearly not the case as the information contained herein and my own experience clearly attest to.
 
A 12 year old thread resurrected so someone could use a linked document and quoted text, both of which are being used out of context, to try and say "see I was right"?

Suggestion, read your own information again, and while your at it, try putting it it in the context intended by the authors, not you trying to prove a point. They are not saying what you seem to think they are.


The DB
 
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freecell said:
"Ten meter ground wave (direct) propagation is much more predictable than "sky wave". Local contacts up to 40 or 50 miles or more can be expected 24 hours a day and is very useful for local communication." ~ Dan Butler, N4UJW ~
Click to expand...


Ground wave is NOT direct propagation. Obviously Dan Butler, N4UJW is one of those amateurs that uses the term ground wave incorrectly.
 
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a ground wave radio signal is made up from a number of constituents. if the antennas are in the line of sight then there will be a direct wave as well as a reflected signal. as the names suggest the direct signal is one that travels directly between the two antennas and is not affected by the locality. there will also be a reflected signal as the transmission will be reflected by a number of objects including the earth's surface and any hills, or large buildings that may present themselves along the signal path.

in addition to this there is the surface wave. this tends to follow the earth surface and enables coverage to be achieved beyond the horizon. it is the sum of all these components that is known as the ground wave.

the direct wave path suffers the least amount of path loss.
the reflected wave path suffers slightly more path loss than the direct wave path.
finally, the surface wave path suffers the highest amount of path loss of the three.

ground wave = direct wave + reflected wave + surface wave.
 
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freecell said:
a ground wave radio signal is made up from a number of constituents. if the antennas are in the line of sight then there will be a direct wave as well as a reflected signal. as the names suggest the direct signal is one that travels directly between the two antennas and is not affected by the locality. there will also be a reflected signal as the transmission will be reflected by a number of objects including the earth's surface and any hills, or large buildings that may present themselves along the signal path.

in addition to this there is the surface wave. this tends to follow the earth surface and enables coverage to be achieved beyond the horizon. it is the sum of all these components that is known as the ground wave.
Click to expand...


YUP, that's the common misconception caused by the misuse of terms. I read that exact quote earlier today. TRUE GROUNDWAVE propagation requires vertical antennas relatively close to the ground and basically peters out drastically above 3 MHz. Ever notice how a broadcast station on 550 KHz can be heard much further away than a similar powered one on 1600? That is the difference in groundwave versus frequency. I don't expect you to believe or even agree. You have never been wrong before so why would you start now.
 
it's the international telecommunications union telling anyone who cares to read that ground wave communications are possible @ 30 mhz. out to 150 kM. over medium dry ground and out to 360 kM over sea water with average salinity, not me.

they made the decision to run the tests with both the (vertical) transmitting and receiving antennas at ground level, not me.

i have worked 11M AM mobile stations from across the desert via ground wave out to distances of 177 kM. with signal to spare. that's not anecdotal evidence, it's a fact.

if you think that this path distance at this frequency was not supported by ground wave propagation then feel free to let me know which of the other three basic propagation modes were responsible for this and why.

free space propagation:
ionospheric propagation:
tropospheric propagation:
 
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I dont know what you call it but I have a friend we talk thats about 50 miles away. Our signals will vary up and down just like DX does some nights. I have made contacts like this up to about 200 miles or AM. Have made them longer on SSB but not often.
 
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The20poundhammer said:
I dont know what you call it but I have a friend we talk thats about 50 miles away. Our signals will vary up and down just like DX does some nights. I have made contacts like this up to about 200 miles or AM. Have made them longer on SSB but not often.
Click to expand...

This sounds like it could be a tropospheric duct enhancement to me... I would guess some nights are quite stable and some not up and down. I used to generally speak 70-80 miles to anyone who could hear me on 11m and considered them locals. And yes signals would be up and down on these and longer contacts. This is likely to be tropo. When there were good lifts on 200 - 260 miles was possible... though normally hilltop to hilltop.

My understanding is there is always a secondary reflection interacting with your direct wave either enhancing or attenuating your signal, this is fixed by QTH geography, ground quality in the far field and your antenna system's radiation pattern. I would have thought this was classified a "ground reflection" and not a ground wave... the distinction is ground wave happens at low freqs and ground reflections happen at most HF freqs.

I always considered real ground wave is for pretty low frequencies and not really applicable at 11m.
 
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How would we tell ? 12 - 15miles is not very far at all. I am not sure I would have thought radiation greater than 0 degrees is not a ground wave... it travels in space not the ground. Of course through every object in its way, houses, cars, street furniture, shops etc. etc.

"Ground Wave propagation uses the area between the surface of the earth and the ionosphere for transmission, it is a method of radio wave propagation. Ground wave propagation is also called surface wave propagation. The ground wave follows the contour of earth and hence it can propagate considerable distances."

That is a definition I got online, the first one that appeared. That is rather a large scope for what a ground wave is. That seems to suggest that ground wave is anything before an ionospheric refraction.

I have no horse in this race really... I had it in mind ground wave somehow conducted through the ground itself for a relatively short distance unless wavelength was very long..

Here this suggests 3 parts to a ground wave.. basically anything that is not a refraction from ionosphere

https://www.electronics-notes.com/articles/antennas-propagation/ground-wave/basics-tutorial.php

So I guess 11m does also have ground wave by those definitions. I am open I don't have a fixed position just as interested in passing as anyone else really.

I would have thought if a wave front is in contact with ground and is also a direct wave on any given path, that the direct wave would be a greater proportion of the received signal as the earth conducted wave would be greatly attenuated, relatively. Unless there were massive obstacles for the "space" wave to get through as well.

It does rather seem this is just a discussion on semantics.
 
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