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Author Topic: 3/8-wave Vertical Height Advantage?  (Read 1473 times)
RFRY
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« Reply #45 on: December 08, 2018, 02:15:29 PM »

...a) Show it both with and without "ground wave"

Maybe you missed, or didn't comprehend the two patterns and the text in my Reply 21 of this thread.

Quote
b) march each pair of plots (w and w/o gnd wave) out to 10,000 kM - say 1kM, 10kM, 100kM, 1000kM, 10,000kM.

That is not needed to prove the reality of what I already have posted on this topic.
« Last Edit: December 08, 2018, 02:21:32 PM by RFRY » Logged
KD6RF
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« Reply #46 on: December 08, 2018, 02:30:28 PM »

...a) Show it both with and without "ground wave"

Maybe you missed, or didn't comprehend the two patterns and the text in my Reply 21 of this thread.

Could be.  What I see is a plot that looks like decaying ground wave as expected, and some words that claim otherwise



Quote
Quote
b) march each pair of plots (w and w/o gnd wave) out to 10,000 kM - say 1kM, 10kM, 100kM, 1000kM, 10,000kM.

That is not needed to prove the reality of what I already have posted on this topic.

Sure it is.  As far as I can tell, the plots shown thus far are plotted without context and only show performance at one or another short range distance, with "ground wave" and what is to become "far-field", and no exact comparison to what you say the NEC far-field only plot would look like - at relevant distances.

If you were to show that there is a large departure - out at ionospheric distances - between NEC far-field only plot, and plot including "ground wave", then you could probably make a really good case.  Which would be fascinating.

« Last Edit: December 08, 2018, 02:45:34 PM by KD6RF » Logged

VTenn Antennas
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RFRY
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« Reply #47 on: December 08, 2018, 02:41:30 PM »

...a) Show it both with and without "ground wave"

Maybe you missed, or didn't comprehend the two patterns and the text in my Reply 21 of this thread.
Could be.  What I see is a plot that looks like decaying ground wave as expected, and some words that claim otherwise

Your conclusion doesn't apply to what I posted in my Reply 21.
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KD6RF
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« Reply #48 on: December 08, 2018, 02:51:44 PM »

Sorry, I'm missing it.  Which part of reply 21 proves enhancement of low angle radiation by "surface waves" - out at ionospheric bounce distances?
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VTenn Antennas
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RFRY
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« Reply #49 on: December 08, 2018, 03:11:39 PM »

If you don't understand what I have posted, then you don't.

 I did my best to state it, and document it.
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KD6RF
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« Reply #50 on: December 08, 2018, 03:31:29 PM »

I think that's the problem - you "state" it, but don't show or prove it out at distance.  

Why not avoid all of these needless long threads - take my suggestion and fill in the proof out at relevant distances:
a) Show it both with and without "ground wave" or "surface wave"
b) march each pair of plots (w and w/o surface wave) out to 10,000 kM - say 1kM, 10kM, 100kM, 1000kM, 10,000kM.

Yes, that would be cool.   And a good advancement in our understanding.
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VTenn Antennas
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KM1H
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« Reply #51 on: December 08, 2018, 03:50:31 PM »

Richard, take the elevation plot in your Post 21 and add one for 1680 kHZ with the full FCC approved ground.

Changing to dB may make it easier than uV/m for some that havent seen that used before. IOW, make it look like an ARRL or EZNEC plot.

Carl
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KD6RF
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« Reply #52 on: December 08, 2018, 04:18:38 PM »

The whole crux of the issue, as I see it, is that the data at short ranges doesn't matter, because surface waves die out quickly ------- sooooo, plotting field intensities at 1 kM doesn't show that "surface wave" provide enhancement for ionospheric propagation.  

Changing plot type or changing to dB doesn't change the fact that short range data is (probably) not relevant.

Showing that there is enhancement from "surface wave" over NEC far-field - out at 1000's of kM distances - is what would prove the theory.

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VTenn Antennas
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KM1H
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« Reply #53 on: December 08, 2018, 05:55:46 PM »

The whole crux of the issue, as I see it, is that the data at short ranges doesn't matter, because surface waves die out quickly ------- sooooo, plotting field intensities at 1 kM doesn't show that "surface wave" provide enhancement for ionospheric propagation
.  


Define quickly and stick to 1680 kHz and 160M.

Since the main lobe contains both the surface and sky wave the condition of that surface wave contributes to the lowest angles or sky wave. It is ALL ONE LOBE or dont you agree?


Quote
Changing plot type or changing to dB doesn't change the fact that short range data is (probably) not relevant.

Changing plot type and scale to what is familiar to hams makes all the difference to understanding this rather simple subject. Why keep fighting it?

Quote
Showing that there is enhancement from "surface wave" over NEC far-field - out at 1000's of kM distances - is what would prove the theory.

Done over and over once you understand a plot that clicks in the gray matter. I dont compute in kM unless Im on a EU or other site that does. OTOH Ive plotted many very long 160M CW contacts, including long path, combined with propagation and other data to arrive at the azimuth angles involved. Not perfect but over several decades it is very informative.

How many here have over 300 160M DXCC entities and 39 Zones under their belt? All obtained from an inland site with very poor ground conductivity and only 1200W on a band known for way over legal power and great locations. One used to post on here several years ago. Understanding how a 1/4 wave vertical really works was a big key to success.

Carl
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WA7ARK
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« Reply #54 on: December 08, 2018, 06:10:51 PM »

...
So you agree that surface wave is not useful for ionospheric communication for hams...

If so, you can appreciate why we think that Richard's postings have little to teach hams.

I cant agree with much of anything you say since you twist things around to suit your own view of reality. And isnt it a little presumptuous to include "we" when so few, if any, agree with you?
What have YOU done on 160? At least Richard is both a ham and BC engineer
So you think I am not a ham? I have been licensed continuously since 1963.

I have up a full-wave loop for 160m, about 50ft agl. I am limited by totally flat land around me, on dry sandy soil in Arizona. Nearest tree worthy of the name is about 20mi away, so I have to put up my own trees (70ft tower and several 40ft aluminum irrigation pipes used as verticals and supports for wire antennas.

By the way, this thread was never about 160m antennas; the OP asked about a 40 and 20 meter vertical, at which point Richard started posting his stuff about broadcast engineering...

Just so you and everybody else understands: My assertion that verticals are not great when erected on dry, sandy, rocky Arizona dirt (compared to dipoles) does not come from NEC; it comes from building them, erecting them and comparing them (in real time) to horizontal wire antennas.

When I tried both commercial and homebuilt verticals on 75, 40, 20, and 17m, I believed that they should let me hear and work DX better than a dipole, and it hasn't worked out that way.

So I started reading, and found many articles that explain why verticals (regardless of how dense a radial field you build, if you elevate the radials or not, if the vertical is short, 1/4wl, 3/8wl or longer) do not live up to expectations if they stand on dry, sandy, rocky dirt. The body of literature out there explains why this is so; and so far everything that Richard has posted should make verticals much better than they are.

My disdain for verticals comes from hands-on experience, not simulation.

« Last Edit: December 08, 2018, 06:20:54 PM by WA7ARK » Logged
KD6RF
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« Reply #55 on: December 09, 2018, 03:15:04 AM »


Quote
Showing that there is enhancement from "surface wave" over NEC far-field - out at 1000's of kM distances - is what would prove the theory.

Done over and over once you understand a plot that clicks in the gray matter.
If so, then my apology for missing it.

Where are those plots showing that this low angle enhancement continues on out to 1000 kM+ shown in this thread?

As said...
Quote
The whole crux of the issue, as I see it, is that the data at short ranges doesn't matter, because surface waves die out quickly ------- sooooo, plotting field intensities at 1 kM doesn't show that "surface wave" provide enhancement for ionospheric propagation.
...and repeating the claim that "surface waves" have some sort of enhancement out at 100's or 1000's of kM is not the same as showing it and proving it.

So, up with the plots bitch!   Cheesy   Just kidding.  We've been watching too much Breaking Bad lately   Grin

But that is what is required to prove the theory - plots showing the low angle enhancement out at 100's or 1000's of kM.... not merely a plot at short distances where everyone already knows that surface waves exist, and not merely more repetitions of the claim.


(I would personally be thrilled to see that Richard is correct, so I'm pulling for him!)



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VTenn Antennas
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RFRY
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« Reply #56 on: December 09, 2018, 04:02:55 AM »

... But that is what is required to prove the theory - plots showing the low angle enhancement out at 100's or 1000's of kM.... not merely a plot at short distances where everyone already knows that surface waves exist, and not merely more repetitions of the claim.

Three observations:

» Radiation launched by a vertical monopole at very low elevation angles including 5 degrees is not a surface wave, because it decays at a rate of 1/r — showing that it is a space wave.

» All space waves decay at a 1/r rate for the entire length of their free-space propagation paths.  My NEC4.2 graphic in Reply 37 has a 1/r decay rate for the path segment shown, i.e., the field is reduced by a factor of 0.5X when traveling along a free-space path whose end-end length doubles.

» There is no scientific need to increase the length of that segment to thousands of kilometers to show that a 1/r decay rate applies. If it applies to a short segment of a free-space path, then it applies equally to all such segments/path lengths.
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KD6RF
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« Reply #57 on: December 09, 2018, 04:12:37 AM »

Sure there is a need.  With all the jumble of field interactions that's going on near-in to the antenna, one could find regions where almost any decay rate applies

With superposition, 1/R, 1/R^2 , 1/R*1.556, etc..., or any combo could be found.  Heck, there are regions where various fileds increase with distance (for example (if memory serves) the so-called "mag loop", where  e-field Increases with distance over a certain small range of distances).  So showing one region at 1/R doesn't prove the behavior you are trying to show.

As they say, 1/R is a necessary, but not sufficient, condition.  

So again, why not just run the dang thing out to 100's and 1000's of kM and settle the issue?
« Last Edit: December 09, 2018, 04:17:02 AM by KD6RF » Logged

VTenn Antennas
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RFRY
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« Reply #58 on: December 09, 2018, 04:22:01 AM »

Looks like at least a bit of progress has been made in that you haven't denied that radiation at very low elevation angles including 5° is not a surface wave.
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KD6RF
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« Reply #59 on: December 09, 2018, 04:33:00 AM »

I haven't "denied" anything!

Nor have I agreed - my suspicion is that the 5 degree region is the superposition of the "far field" terms, and the "surface wave" terms.

Seriously dude, I am pulling for your because this sort of exploration is what makes this hobby (and careers) really interesting.  But you haven't proved your claim yet with the limited data provided.

I however, am making only 1 simple claim ---> And it is that "The provided data, that is limited to only near-in region(s), doesn't prove your claim."  And as  I keep saying, just run the dang thing out to 100's or 1000's of kM, and see if your claim still holds true!


« Last Edit: December 09, 2018, 04:36:20 AM by KD6RF » Logged

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