sigma4 article is online

[Henry HPSD]

Hello Homer,

Yes, I do understand....
And we indeed need to focus on "what would be best".

Though your question "why" it has worked better is a question for which I can not find the answer. There are so much variables.
The "bottom" line is....if we illuminate all those variables and put them up at same "reasonable" tip height the difference wont be there....simple as that.

QUOTE Homer:
I stand with my unshakable conclusion etc....

For my understanding....
Why ? As the graph shows the Sigma is better at that distant.
Amd that is what you experienced ?

Im almost afraid to ask....but..you do realise a signal which is received with -84 dB is stronger compared to -86 dB ?

Kind regards,

H>

http://s1.bild.me/bilder/120914/5866777antenna_height.png"

 

[gamegetter]

my experience in the real world has been that the time of year(seasons), weather conditions(have you ever noticed how quiet it gets AFTER a storm comes through-i love to get on the radio after they pass and listen to stations that i can't normally hear with all the normal noise levels), and time of day(night and day) can all have an affect on communications.

 

[Marconi]

Homer, I model using Average Earth, unless I have a specific reason to change the ground description. My area is in the 15 zone, I just got that wrong long ago on the ARRL chart that is not so clear.

I'm not sure, but maybe we have a difference of opinion, based how this issue works. I've posted this idea to try and explain my thinking on this before and I can't go into all the aspects involved in this issue. So, maybe I did not describe my idea well or it is just too complicated to get clear, without others being there when modeling. After I learned to model with Eznec, is when I changed my thinking on this. I use to think I was in the 30 zone.

However again, since I was able to model I have determined my idea about how this all affects an antenna was exactly backwards from my earlier thinking. I know I'm in trouble again for changing my mind about this stuff.

I've said from the beginning, "...I don't sense much difference in my antennas...even when I mount them on the same pole and wasn't comparing antennas. So, since I was saying sameO sameO story about my antenna results, and they all seemed to work well...I figured the best performance might just prevailed in areas like mine and similar areas all around. I also had the thought...maybe that was why I don't see differences in signals like others report.

I never figured it was about my radio having 6db/Sunit or anything else either. I also figure if an antenna was in an area with poor soil conditions...it would perform poorly, and maybe then you could detect differences more easily for some reason that I did not understand. There is more to all this obviously, and in part it has to do with and ideas about having good working radials, vs. poor, or no radials, or so I believe, just .

Bob and I have discussed these ideas way back, and maybe I just misunderstood what he was getting at...or we both have changed our minds on this subject, again, or it was just me.

My models show poor soil looks to improves the gain and effects the pattern and angle a bit too, but I'm not sure about direction of angle...it may look to go lower. Very good soil (higher numbers) typically show the gain drops as the soil gets better on this scale.

I tend to see my models also show a drop in gain, as I improve the accuracy of the models...so I think I'm understanding this pretty close. Understand though, in my book...nothing in this antenna business we talk about ever looks to me to ever be 100%.

The short story is, if I want to show a model with a better gain, then I can set the model with poor or worse poor soil conditions. If I don't indicate this...then who knows. Then the gain and pattern look improved and show more gain. I subtly demonstrated this idea recently in my J-Pole thread, and that is how I got those models of my J-Pole to show remarkably more gain as you will note.

Also note that physically being over sea water like in a boat or on a ferry...improves my mobile range remarkably in my experience. High bridges also over water and high up as a similar effect, although I think that might be mostly height...and that should prove something of the idea about height that I try to describe with the S4 advantage.

I also note that from Galveston Island, I find it difficult to impossible to contact 60+ miles base to base, or base mobile for sure. But there are hot spots on the Island that are just like being on sea water...and that is pretty remarkable too, and it is repeatable from such spots most of the time too. I will describe these areas as being really close to inland water like a low bridge or as sea water cut or bay that we can get close up to.

Another thing about a model set over sea water is as the height increases the gain decreases, so better reflection might be working in that good number area.

I'll post a model or two, and we'll see, OK?

Eddie.

 

[Marconi]

Hello Homer,

Yes, I do understand....
And we indeed need to focus on "what would be best".

Though your question "why" it has worked better is a question for which I can not find the answer. There are so much variables.
The "bottom" line is....if we illuminate all those variables and put them up at same "reasonable" tip height the difference wont be there....simple as that.

QUOTE Homer:
I stand with my unshakable conclusion etc....

For my understanding....
Why ? As the graph shows the Sigma is better at that distant.
Amd that is what you experienced ?

Im almost afraid to ask....but..you do realise a signal which is received with -84 dB is stronger compared to -86 dB ?

Kind regards, H>

http://s1.bild.me/bilder/120914/5866777antenna_height.png"

Henry, we have also heard in this discussion, that the S4 design does not fair any better than other shorter CB vertical antennas at closer in distances, but that it begins to really shine much farther out, and for sure at the further most fringes of its range.

I don't think I see that supported in your real world graphs on pages 33-34...if I'm reading it right.

How say you?

 

[HomerBB]

Hello Homer,

Yes, I do understand....
And we indeed need to focus on "what would be best".

Though your question "why" it has worked better is a question for which I can not find the answer. There are so much variables.
The "bottom" line is....if we illuminate all those variables and put them up at same "reasonable" tip height the difference wont be there....simple as that.

QUOTE Homer:
I stand with my unshakable conclusion etc....

For my understanding....
Why ? As the graph shows the Sigma is better at that distant.
Amd that is what you experienced ?

Im almost afraid to ask....but..you do realise a signal which is received with -84 dB is stronger compared to -86 dB ?

Kind regards,

H>

http://s1.bild.me/bilder/120914/5866777antenna_height.png"

Henry, I read the graph backward. Thank you.

 

[Henry HPSD]

1- The first table does...
(it gives several dB extra compared to those others. for most due to its height of course.)

2- The second doesn't. (equal tip height no losses etc)
That indicates that if "all" is done well they should be more or less equal at same tip height. If that isn't the case....you know there are issues.
Which one that is....that is the question.

The search must be in the direction of :
"why" the other isn't performing that good,
instead of "why" is the "better one" performing so good.
And that is difficult to realise.

Kind regards,

H>

 

[Henry HPSD]

Homer !

Thank you!
That is what im looking for...and I was thinking...and thinking...hihi.

For me it is normal to "know" that...
As in "antennas" you work with those figures on regular base, in fact measurements or often done like that.

Its welcomed that you didnt indicate it like that at first glimps.
As i now know if you didnt at first..there must be many !
So i need to "set more text along with it".

Ps the reason i like to use "dB" instead of uV/m as "dB" gives a good indication about difference for most to visualize ....a figure for say 0,1 uV to 0,13 uV ...ehm oke ?
Then most will ask questions ...oke 0,03 uV...how much is that ?
But if they "see" 2 dB difference, they have a better "idea".
(it is relative easy to "re-calculate" though..)

Kind regards,

H>

 

[HomerBB]

Yes, Marconi, I have read that poorer ground improves antenna potential gain, too. It is an easy thing to forget . . .
A different sort of conductivity map seems to show that.

http://i1205.photobucket.com/albums/bb426/Chal_Cirilo/radioreception_zpstpmejff5.png

 

[bob85]

Eddie,
i see my hybrid sigma has an advantage over other antennas at any reasonable distance if they are on the same mast/coax,
The advantage becomes more noticeable out on the fringes,

Yes it can make a contact that the shorter antennas struggle with or can't make at all,
But as i said earlier, In my situation the taller antenna has an advantage over surrounding obstacles/terrain,

I would expect my surroundings to amplify the advantage seen in Henry's graph vs somebody with a flat terrain comparing the same antennas on the same mast/coax.

 

[HomerBB]

Bob, I don't know what part of England you are in, but looking at soil conductivity it ranges from 1 - 30, with an average of 8 - 10.
So it may be we share soil types.

 

[The DB]

There is more than one rating for soil. You have its conductivity, and its dielectric constant.

Conductivity is what most people think of when looking at soil quality at RF, and for the most part, even good soil isn't really that conductive.

The other aspect, the dielectric constant, is just that, the soil acts as a dielectric. This relates to other aspects of the earth, such as determining how far a signal will penetrate the surface of the earth and more.

Also, these factors change with RF frequency. Most maps of earth quality are for near AM broadcast frequencies. Do not assume the ground data for such frequencies will be the same for CB frequencies, which are in the neighborhood of 27 times higher than AM broadcast frequencies...


The DB

 

[Marconi]

Ps the reason i like to use "dB" instead of uV/m as "dB" gives a good indication about difference for most to visualize ....a figure for say 0,1 uV to 0,13 uV ...ehm oke ?
Then most will ask questions ...oke 0,03 uV...how much is that ?
But if they "see" 2 dB difference, they have a better "idea".
(it is relative easy to "re-calculate" though..)

Henry, this is why I ask DB how this new type of data compared to the performance we see with dbd or dbi results. I think we can all see the difference is very small, similar to what I contend most of this CB antenna business is really showing when you get right down to the nity-grity and the science. IMO, the CB world blows all these differences into bigger differences, so they can sell products. If we look close at the reality of all this...it looks to me my models tend to show about the same, differences are generally more accurate on the small side in results.

Eddie,
i see my hybrid sigma has an advantage over other antennas at any reasonable distance if they are on the same mast/coax,
The advantage becomes more noticeable out on the fringes,

Yes it can make a contact that the shorter antennas struggle with or can't make at all,
But as i said earlier, In my situation the taller antenna has an advantage over surrounding obstacles/terrain,

I would expect my surroundings to amplify the advantage seen in Henry's graph vs somebody with a flat terrain comparing the same antennas on the same mast/coax.

Bob, when I use to work my SD'r up at about 50' feet to the hub on a pushup pole, and at another time I had a knock off in a tree...I don't know how high, but it was higher, I could not sense any difference over the period of time between those installs. The only thing I ever did that could tell was recording results I saw.

I did recall that both installs worked at least as good or better than guys around me...but I was not comparing signals and I never consider what might be my fringe zone or how I could tell how far an antenna signal can go. Sometimes I could hear talk, but I couldn't copy...but in my case that only happened when comparing my horizontal beams to one of my verticals.

My old CB SD'r buddy Johnny, who's handle is Nimrod, had his SD on a 50' foot pushup, sitting inside of two 10' foot sections of schedule 40 conduit, and attached to the roof peak of his two story garage apartment. We figured it was maybe 70' feet high to the base. We use to talk to guys in San Antonio of a morning 200 miles away, and all I had was a barefoot CB radio and my SD'r up about 50' feet. On the same token I've had contacts as close as 40-50 miles that sometimes I can hear but not fully copy. I can't explain that other than just saying it was conditions.

This was not during times when DX was working either. Johnny used a 100 watt amp, and guys use to claim we were both running big amps. That said, we were not the only ones around us that talked that far...so I didn't consider the SD'r was anything special and the lack of power didn't seem to make that much difference either. I can't explain that either.

Bob, I've made lots of local type contacts noted on my old Signal Reports that were far off, and some were members on this forum in the Texas area. I can't really tell you why, but I just though it was mostly due to my antenna height that did it for me, and even with more modest heights I've run in the recent past. I just didn't see much difference either way. I don't think I have ever has a situation where one antenna could make a contact while another did not...excepting maybe when I was working my beam antennas and I could switch to the GP and maybe I could not copy.

Yes, Marconi, I have read that poorer ground improves antenna potential gain, too. It is an easy thing to forget . . .
A different sort of conductivity map seems to show that.

http://i1205.photobucket.com/albums/bb426/Chal_Cirilo/radioreception_zpstpmejff5.png

Thanks for the additional chart Homer. I see where my area is only 15 and not 30, and if my models tell the effects of ground descriptions (GD) correctly, I'm better off at 15, than at 30, which I use to believe made the difference here. So I was wrong in my believe on this issue at some point in the past.

Models do show that GD differences can effect the gain and pattern in major ways, but I can only assume those differences also result when using a real antenna. I don't know if I can tell for sure though. I have been working antennas for a long time, and I can't tell you for sure I have never had a "uh oh moment" where I realized I was in the the fringe zone, and one antenna made a signal I could fully copy while the other antenna didn't.

I did experience one occasion with my A99 that had worked very well for me, but on raising it up nearly twice as high in a pine tree...I was not impressed and I could not explain that. Maybe that was the idea that Henry talks about suggesting how good the other antenna was working. After I took it down to remove the tree several years later...the antenna worked fine. I had 150' of brand new Davis RG213, and the A99 tune was pretty right on with good performance again.

I am pretty sure however that in most cases the height of antennas can make detectable differences in performance, if nothing else seeing the TX signals improve a bit. IMO, if you want good performance, just raise your antenna up higher.

The way I have experienced this issue for performance is all my antennas at and sometimes just being near the same tip heights will perform very close to the same. Even if there is a difference IMO it is generally too small to see just using our radio. I also see a possible point in going higher where this differences, change in height, becomes minimal in effect, and models tend to show that too...just like I think Henry's report shows us.

 

[HomerBB]

Marconi, I recall you building models that indicated optimum heights.
I have read that in general a 1.5 to 1.6 wavelength height for what I assume is the current maximum is best. Also, that when an antenna is placed higher it tends to be less good close in.
Other things appear to affect an optimum height, too. As I understand it the surface wave arriving at 180 degrees phase difference would cancel the signal arriving as a line of sight, or space wave, while a surface wave arriving at a different degree that is non-canceling could add gain to a receiving antenna. And this difference might be made by little adjustments in height which would be different for various bands.

All to say it is not so difficult to visualize situations that could account for differing results, or similar results from different antennas based on mount heights alone.
The truth is that just raising an antenna higher and higher can lead to a degradation in performance as the optimum height is by-passed. It can be different for different kinds of terrain, like Bob said, beside the constant dielectric or soil conductivity of the ground - hills, plains, mountainous, etc.

That said, and acknowledged, when the very same location with differing antennas having the current maximums in the same place results in different performances it leads me to continue to explore possible explanations.

2- The second doesn't. (equal tip height no losses etc)
That indicates that if "all" is done well they should be more or less equal at same tip height. If that isn't the case....you know there are issues.
Which one that is....that is the question.

The search must be in the direction of :
"why" the other isn't performing that good,
instead of "why" is the "better one" performing so good.
And that is difficult to realise.

Bob has settled this for himself with an admission his antennas were mounted at the same bottom height, which does not describe my situation.
When I compared verticals, 5/8, EFHW, center fed dipole, Astroplane, I used only antennas I had built. Owing to the quality of each of them potentially being questionable Henry's suggestion that something may be wrong with the lesser performers. What I can do is eliminate the only two of the list above that might ( I speak generously) be called into question because of their lossy matching systems, the 5/8 GP, and the EFHW. What I now still have is two antennas that DO NOT have lossy matching systems, a center fed dipole that is vertical, but not side mounted (the coax traveled up through the lower tube to the feed point at the center), and the Astroplane. These two are naturally resonant antennas versus one antenna with a very large matching network. I am matching up the two best (IMO) 1/2 wave antennas with reespect to superior matching systems (none) that are center fed (balanced?) against an end fed antenna with a complicated highly and delicately sensitive to tuning matching system.
All these antennas were mounted, as I've said, with current maximums at the same elevations. They were coax choked identically, and isolated from the mast, and the end fed with a complicated matching system antenna performs best.

This was not a contest between different persons antennas in different states or on different continents.

As a note, the areas I was able to work into with the Vector 4000 I did not work with the others also have the same terrain I have, and the same soil conductivity.

 

[bob85]

Eddie,
Contacts 200 miles away on 27mhz using any vertical in this area is short hop skip and rare,

Using fairly low mounted antennas as you do about the best consistent all day every day contacts would be somewhere around 50-60 mile as the crow flies, and that requires significantly more than 4w with all the local noise we get nowadays compared to back in the late 70's earl;y 80's,
I talk to a couple of guys around 40miles from me anytime i like but the 50-60 miles distant guys in the same direction were lost when i swapped from the sigma hybrid to the i-10k on the same pole,

If you go up a 1000ft+ hill you can do better, 40+ miles from the mobile is not difficult on 4w FM,


Homer.

I don't know what the soil conductivity is here but i metal detect and can tell you soil conductivity changes from field to field, even different parts of the same field,
ground tracking adjusts every few sweeps of the detector, walk 20 yards and you can be in different soil conditions,
Near me we have a major roman road 4-5 feet below the modern ground level in the farmers fields,
soils vary from heavy wet clay through loamy to well drained sandy soil, mineralisation ranges from low to failry high,

Underneath the soil is magnesian limestone
In places the stone is visible as outcrops and in others it could be 7 - 8 feet below the surface,
Its anybody's guess what my ground reflection is hitting,

I think conductivity maps are too generalized for any place where there has been human activity deforestation mining quarrying and agriculture for well over 2000 years,

One thing about FM is you can very easily hear when multipath reflections are causing signals to move up and down like a fiddlers elbow at a variable rate with the corresponding changes in quieting of the receiver when the reflector is moving,
You can hear and see on the s-meter as the two or more signals arriving at your antenna are causing cancellation and summing,

Planes flying in and out of leeds/bradford airport cause very noticeable multipath flutter between me and my buddy,
With experience you can develop a "radar ear" have a fair idea where it is between us, you always hear it on the radio well before you hear the planes engines,

Reflections can play a big part in what we receive at our antennas.

 

[Marconi]

I have experienced talking long distances too, but I never thought it was primarily the antenna I was using that made that happen. I really didn't know, but still I have never been able to see big differences with any of the CB antennas I have either.

I realize that nobody wants to hear that, because most have their own ideas why their antenna is/was the best, and/or due to the excitement a new installation can present, like Henry talked about.

Bob, a difference between my experiences and your experiences is there were other locals around me that were also making the same contacts I was...I wasn't the only one that could copy and talk back to these guys.

In your case you were the only one around you that could talk to the guy you've describe some long miles away.

I think most that was due to your antenna being 70' feet high on a scaffold pole in your dad's pasture, while all your buddies around you were like me or less in height. My main claim has always been that if I can get my little 1/4 wave ground plan up as high as my taller high gain antennas I can produce a signal that most will never realize a difference. So, I see in your experience, you did much the same, you just went up higher than everybody around you and to me that might explain a lot of what you saw. I might even agree that you likely never saw another antenna show to be similar at a distance, because of the difference in height, and being you were using the same pole in all the comparisons.

Since most of my testing was giving due consideration for getting the current maximums close or the same, I'm also not surprised you saw a difference. I can't say the same in Henry's case however, but maybe his homemade antenna with all the nice effective tricks that you have suggested to us all for good installation practices...made the big difference he reports.

I see some nice increases in gain with my Eznec models...when I remove the bad currents on the mast, but that proves nothing until we test in the real world...and maybe that is the difference that Homer reports. If so, we should be able to duplicate that effort over and over again with all antennas that show CMC, and we might have a better understanding for the answer.

You and Homer have told your experiences in this regard, and I have told you only a couple of mine. Maybe we're all wrong, and it is just impossible to really tell in our circumstances why we see three different results going on.

I'm , but I think we can believe what Henry shows us in this regard, there just isn't that much of a difference between all of these antennas, unless the fringe zone is like an on and off light switch so we can really tell when all those lesser antennas just run out of detectable radiation.