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Marconi's video comparing the Gain Master vs. AstroPlane
- Thread starter Marconi
- Start date
Thanks, Henry.
Illuminating and helpful.
So which of the methods would you advise using? #4? #1
I am trying the top height the same now. But I know I'll ultimately be forced to use the common mounting height because I will not be able to put a 28' tall V4k at the same connector height as the connector height of the AP. The V4k is 2.5 times taller than the AP, and several times heavier. I am looking at potential modifications to my mast to increase the possibility of of raising antennas a little higher than I currently can.
If only I had a 330' tower that I could stand on the ground to mount the antenna on . . .
Illuminating and helpful.
So which of the methods would you advise using? #4? #1
I am trying the top height the same now. But I know I'll ultimately be forced to use the common mounting height because I will not be able to put a 28' tall V4k at the same connector height as the connector height of the AP. The V4k is 2.5 times taller than the AP, and several times heavier. I am looking at potential modifications to my mast to increase the possibility of of raising antennas a little higher than I currently can.
If only I had a 330' tower that I could stand on the ground to mount the antenna on . . .
Thanks, Henry.
Illuminating and helpful.
So which of the methods would you advise using? #4? #1
I am trying the top height the same now. But I know I'll ultimately be forced to use the common mounting height because I will not be able to put a 28' tall V4k at the same connector height as the connector height of the AP. The V4k is 2.5 times taller than the AP, and several times heavier. I am looking at potential modifications to my mast to increase the possibility of of raising antennas a little higher than I currently can.
If only I had a 330' tower that I could stand on the ground to mount the antenna on . . .
I dont understand why this is so difficult to figure out you mount the feed point of the antennas at same base height that is the way you make a comparison of 2 antennas. Why are people artifically trying to give one antenna a advantage over another. Testing antennas is easy, yet you guys are making so many variables come into play. Again I will use a mobile for example when you put on a 102" whip on a vehicle and test it you then change and put a coil antenna on the vehicle for a comparison the 102" whip is taller so do you ty and raise the coil antenna so the tips are the same? NO, you ask why not? because you are taking away the benefit of a 102" whip..
You have a tower at home that the mast height is 50' from the ground, it has a 1/4 wave GP on top the antenna height is 59', you then decide to upgrade to a 5/8 wave, Ok so you mount the antenna, do you lower the 5/8 wave so the tip is at 59' or do you mount it the same as the 1/4 wave and enjoy the benefit of a 5/8 wave.
There are common laws of physics here longer antennas have more gain/lower TOA, changing the height of the feed point makes antenna work better. Can you get a 1/4 wave GP to work better than the best 5/8, .64 wave ? Yes just raise the 1/4 wave up higher. Stop trying to make the antennas equal because they are not, seems many here are trying to take away the benefit of the longer antenna cause in the end thats the benefit of it's performance , Length.
Of course it is valid, and it isnt with respect to someone who doesnt want to change thier mount. Look people buy new antennas why? to increase performance from thier previous antenna. If you are gonna raise it up , why not just raise the old antenna up, and save your money cause your old antenna will perform better higher in air.
This test basically isnt valid, (see above) if your gonna raise your mast stick with your old antenna. Otherwise you again arent comparing antennas. Again see my comparison using a mobile antenna. Let me ask you what works better on the roof of a vehicle 9 out of 10 times a coil antenna or a 102" whip, if the 102 works better do you somehow try to raise up the coil to match it's performance? I don't think so since on a vehicle the mount is (usually)fixed and you are comparing antennas equally, any other way is not correct.
You answered your own question so stop there.
This is totaly wrong, yes it is where the rubber meets the road but your going down the wrong street. You are correct antennas exhibit different properties that is the benefit of them being better than the other yet again you are trying somehow to make them perform the same by changing the criteria. Anyone can get a 1/4 wave to work better than a 5/8 wave, it is so simple maybe you guys will catch on, just raise it up.
Ill end it with this because this is so simple and seems the masses arent grasping it, when you model a antenna you put it's elevation in height above ground ( where the base of antenna is located above ground) you model the antenna and get a gain reading. You now model antenna #2 it also is modeled at same height above ground. You get a gain figure and compare it to antenna one and decide what antenna will work better. You dont raise up the anteena up that didnt perfrom to equal the other. Again all things being equal a longer antenna will outperfom a shorter one, unless we try to make the antennas have a advantage over the other.
Mr Suburban,
Hello, and thanks for your replies. I have absolutely no argument with anything you just wrote. I agree.
However, there are some key differences in what I said about each example.
With #2, I am perfectly willing to concede to your logic.. Thank you.
#1 and #3 are the practical way of doing things. This is what I said. I stand by that. The advantage will go to the longer antenna in most, if not all, cases.
#4 Here is the rub. This whole idea of testing is about the DESIGN of given antennas, not about height. There are several threads here on the forum that have examined the various designs of several antennas. In particular the V4k, The SGM, and now this one looking at the AP. Although I do not expect complete agreement with what I am attempting to say here, I will persist in noting there is what I believe to be absolute validity to testing the DESIGNS of the various antennas by comparing the designs from the point of their optimum radiation. Yes, the variables of height, thickness of materials, matching systems. etc, do offer advantages to some over others, but that is what designs do. If it were possible to measure dbi in the theoretical environment of space the answers would come easily, and all would agree with the results. It is not possible for anyone other than the astronauts, and unfortunately for we mere mortals, it's not a part of their job description. Furthermore, it is not where we live.
So here we are, doing our best to simulate results in the real world where the closest we'll ever get is to set the radiation at the common level (which is precisely what theoretical dbi space modeling does) in a variety of QTH conditions and see what these antennas really do in terms of their designs. It is the different advantages of their designs that we are wanting to demonstrate. And in the process explain the why of it or the why not for those interested.
When the day is done, some of us will change to something else, and others of us will remain with the one we've got presently, while others will look at whichever test offers them some insight to the solution to their current antenna performance issue and will simply raise their antenna higher if they can, etc.
Hopefully I have explain the logic I've employed to my reasoning without alienating anyone in the process. I fully embrace your arguments as presented. I am just talking about saddling the horse for the rodeo, not the Kentucky Derby.
Respectfully,
Homer/Charles
Hello, and thanks for your replies. I have absolutely no argument with anything you just wrote. I agree.
However, there are some key differences in what I said about each example.
With #2, I am perfectly willing to concede to your logic.. Thank you.
#1 and #3 are the practical way of doing things. This is what I said. I stand by that. The advantage will go to the longer antenna in most, if not all, cases.
#4 Here is the rub. This whole idea of testing is about the DESIGN of given antennas, not about height. There are several threads here on the forum that have examined the various designs of several antennas. In particular the V4k, The SGM, and now this one looking at the AP. Although I do not expect complete agreement with what I am attempting to say here, I will persist in noting there is what I believe to be absolute validity to testing the DESIGNS of the various antennas by comparing the designs from the point of their optimum radiation. Yes, the variables of height, thickness of materials, matching systems. etc, do offer advantages to some over others, but that is what designs do. If it were possible to measure dbi in the theoretical environment of space the answers would come easily, and all would agree with the results. It is not possible for anyone other than the astronauts, and unfortunately for we mere mortals, it's not a part of their job description. Furthermore, it is not where we live.
So here we are, doing our best to simulate results in the real world where the closest we'll ever get is to set the radiation at the common level (which is precisely what theoretical dbi space modeling does) in a variety of QTH conditions and see what these antennas really do in terms of their designs. It is the different advantages of their designs that we are wanting to demonstrate. And in the process explain the why of it or the why not for those interested.
When the day is done, some of us will change to something else, and others of us will remain with the one we've got presently, while others will look at whichever test offers them some insight to the solution to their current antenna performance issue and will simply raise their antenna higher if they can, etc.
Hopefully I have explain the logic I've employed to my reasoning without alienating anyone in the process. I fully embrace your arguments as presented. I am just talking about saddling the horse for the rodeo, not the Kentucky Derby.
Respectfully,
Homer/Charles
Hey Henry. This question might not be on point since we're discussing the testing of CB type verticals, but have you ever compared basically similar antennas with different feed schemes, maybe using a 1/2 wave dipole or something similar, with no matching vs. gamma vs. hairpin or some other?
If so, how important is tuning and matching for real world gain if you where able to notice? Some advertisers hype their claims of improved performance in their products due to their superior matching over competitors. I'm talking about being able to really tell with the regular tools available to the typical CB guy, not lab quality testing.
Also, how much does this matter in modeling results, using Eznec5, and considering a model without using the matching feature at all? I know there are antenna characteristics that will change in this situation, but I'm wondering more about the pattern, angle, and gain changing significantly when we don't use such a feature in the model design.
I know that a 5/8 wave GP is not resonant, and I made a model without using the matching feature. I was wondering what the difference might be, if any, when doing the model this way as apposed to including matching the antenna?
If so, how important is tuning and matching for real world gain if you where able to notice? Some advertisers hype their claims of improved performance in their products due to their superior matching over competitors. I'm talking about being able to really tell with the regular tools available to the typical CB guy, not lab quality testing.
Also, how much does this matter in modeling results, using Eznec5, and considering a model without using the matching feature at all? I know there are antenna characteristics that will change in this situation, but I'm wondering more about the pattern, angle, and gain changing significantly when we don't use such a feature in the model design.
I know that a 5/8 wave GP is not resonant, and I made a model without using the matching feature. I was wondering what the difference might be, if any, when doing the model this way as apposed to including matching the antenna?
i couldn't agree more,
as soon as you change any other parameter other than replacing one antenna directly with another, you are no longer comparing the design of the two antennas, you are comparing the design plus the parameters you changed.
i could just see someone adding a 4ft block of metal to the roof of their vehicle to compare a fullsized 1/4 wave against a loaded 5 ft whip 1/4 wave, thats just fucking ridiculous. i don't see why its any less ridiculous if you do likewise on a base station mast.
if you start trying to compensate for the manufacturers design failings you are just kidding yourself on.
to put it another way, if a 5'6" bird is uglier than a 6' tall bird, putting her in 6" high heels ain't gonna change the fact she's still an ugly fucker.
Homer, Good Post hopefully you didnt take my post to you in the wrong way. It's just how we communicate in this part of the country.
If you want to take advantage and see the difference in the designs then that is all the more reason to mount them at the same height this way you are comparing the design difference and nothing else. The design of a 5/8 wave lends itself to be taller than a 1/4 wave. Again I htink you are missing the point elevating the feed point of any antenn will improve gain. You mentioned Free space modeling, again that exactly makes my point the height above ground means nothing in a model the bottom of the antennas are the same location Just look at the X, X, Z coordinates, the antennas that are compared in free space the feed point is equal and the taller antenna is still taller. That is a design feature of the antenna sorry the Astro planes feed point is mounted up high, that is a design feature, maybe it is'nt a good one maybe it is. Again any type of comparison testing has to be done at same feed point height otherwise it is not a comparison.
At least we are getting somewhere as far as understanding each others point of view, and why we do it in a variety of ways. i am learning, and if I do not stick my neck out dangerously and express my understanding I won't get beyond the limits of my own thinking.
Thanks for the replies.
I get it.
I was only trying to do two things.
Air out my thoughts so I could be brought on point. And try to explain why I thought folks try the comparisons in different ways.
I appreciate the answers and everyone's honesty. I am in no way offended.
It's all good, and it really is simple.
Thanks for the replies.
I get it.
I was only trying to do two things.
Air out my thoughts so I could be brought on point. And try to explain why I thought folks try the comparisons in different ways.
I appreciate the answers and everyone's honesty. I am in no way offended.
It's all good, and it really is simple.
As an aside:
"Whad yu doin', Boudreaux?" asks Thibodeaux.
"I'm tryin' ta measure how tawl dis poe," replies Boudreaux.
"Why yu don' lay down da poe?" asks Thibodeaux, "it sho be easier dan whad yu doin'."
"Ah don' wan' ta no how long dah poe is, Ah wan' ta no how tawl dah poe is," says Boudreaux.
I think in free space, considering there is neither up, down, high, low, north, south, right, left, in, out, over under, etc, none are taller, but some are longer.
Thibodeaux finds Boudreaux trying to push a thin floppy measuring tape up the length of a pole.MrSuburban said:
"Whad yu doin', Boudreaux?" asks Thibodeaux.
"I'm tryin' ta measure how tawl dis poe," replies Boudreaux.
"Why yu don' lay down da poe?" asks Thibodeaux, "it sho be easier dan whad yu doin'."
"Ah don' wan' ta no how long dah poe is, Ah wan' ta no how tawl dah poe is," says Boudreaux.
I think in free space, considering there is neither up, down, high, low, north, south, right, left, in, out, over under, etc, none are taller, but some are longer.
Hello Mr suburban!
Aways intresting to disagree!.
Here's my thought..:
Quote Of Mr suburban:
I dont understand why this is so difficult to figure out you mount the feed point of the antennas at same base height that is the way you make a comparison of 2 antennas. Why are people artifically trying to give one antenna a advantage over another. Testing antennas is easy, yet you guys are making so many variables come into play.
There are common laws of physics here longer antennas have more gain/lower TOA, changing the height of the feed point makes antenna work better. Can you get a 1/4 wave GP to work better than the best 5/8, .64 wave ? Yes just raise the 1/4 wave up higher. Stop trying to make the antennas equal because they are not, seems many here are trying to take away the benefit of the longer antenna cause in the end thats the benefit of it's performance , Length.
End of Quote Mr suburban.
Oke, Ill try again…It is not as difficult to understand.
Imagine a 20 wavelength long collinear antenna.
Now bottom feed it or central feed it…that means a height advantage of 10 wavelengths.
It would only be logical wich one in this case is the winner. with your average tetst with the village next door.
Secondly feedpoint height?....oke..here goes again…take a halvewave endfed vertical…
You could bottom feed it but top feed is also possible ofcourse. Again a height advantage.
Your example of testing with mobile antenna and the direct link to feedpoint height is of practical use. But it is not based on “honest” comparisment.
The same would be the case with a ¼ wave MW antenna or a ½ wave MW antenna simple for practical use you cant put them equal.
That’s one of the reasons antennas are scaled in order to test them!
Going through your last alinea: .
I agree that longer angtennas have most of the time more gain. But NOT always a lower TOA.
There are quiet a few more situations where a ¼ GP can outperform a 5/8 wave and that is not only by adding the heigth the 1/4 wave.…that "thinking"would be quite inaqurate.
And don’t set your mind only to verticals. Think about horizontal antennas aswell…if you want to compare antennas and set a “standart” you must involve every possible antenna, not only mobile antennas.
The question asked is what do we want to measure? If that is Gain.
It is commen knowledge that a 5/8 wave has about 3,5 dBI Gain.
If you agreed on that, you agree on being wrong when saying “feedpoint” height.
That 3,5 dBI is under a certain angle isn’t it?
If you would compare that with other antennas with a different take off angle (but at the same feedpoint height) You will have a much larger difference. Though we already esthalished the gain of a 5/8 wave as a “known” fact.
You are speaking about the advantege of ground gain...oke...with the radiating center of the antenna of both antennas at equal distance from the earth that advantege of gain would be equal!
You can verify that by the fact people use stackmaster for a horizontal stack in order to change TOA.
Now, I can understand if one tests mobile antennas it is feedpoint height, as that would be practical as mentioned. And the tests will show the results everybody else will see when using it…however I do hope you understand that “practical reasons” are not always ..”fair”…
When we test antennas we do everything to get as close as we can to a "freespace" model. That would not be feedpoint heigth. As that wouldnt not give a equal groundgain...also the TOA can be completly different.
So either you should keep that last factor in mind and dont do DX test.
And finnaly, say you would have 2 antennas "sitting on the ground".
one is 1 meter long the other is 20 meter long. Both are bottum end fed.
The test antenna is a 1 meter high antenna placed at 10 meters heigth at a equal length away from horizontal distance from the two antennas.
The route a signal most travel from the two antennas under test are by far not equal.
I do not know if you ever heard of the Friis transmission formula..that tells is distance has influence on signal strength. And that is one of the things that is not equal with the same feedpoint heigth. Therefor i dont see how you can be correct.
If you place antennas at feedpoint height, exactly then people are giving bennifits to certain antennas.
Regards,
Henry
11 meter Dx antenna systemx
Aways intresting to disagree!.
Here's my thought..:
Quote Of Mr suburban:
I dont understand why this is so difficult to figure out you mount the feed point of the antennas at same base height that is the way you make a comparison of 2 antennas. Why are people artifically trying to give one antenna a advantage over another. Testing antennas is easy, yet you guys are making so many variables come into play.
There are common laws of physics here longer antennas have more gain/lower TOA, changing the height of the feed point makes antenna work better. Can you get a 1/4 wave GP to work better than the best 5/8, .64 wave ? Yes just raise the 1/4 wave up higher. Stop trying to make the antennas equal because they are not, seems many here are trying to take away the benefit of the longer antenna cause in the end thats the benefit of it's performance , Length.
End of Quote Mr suburban.
Oke, Ill try again…It is not as difficult to understand.
Imagine a 20 wavelength long collinear antenna.
Now bottom feed it or central feed it…that means a height advantage of 10 wavelengths.
It would only be logical wich one in this case is the winner. with your average tetst with the village next door.
Secondly feedpoint height?....oke..here goes again…take a halvewave endfed vertical…
You could bottom feed it but top feed is also possible ofcourse. Again a height advantage.
Your example of testing with mobile antenna and the direct link to feedpoint height is of practical use. But it is not based on “honest” comparisment.
The same would be the case with a ¼ wave MW antenna or a ½ wave MW antenna simple for practical use you cant put them equal.
That’s one of the reasons antennas are scaled in order to test them!
Going through your last alinea: .
I agree that longer angtennas have most of the time more gain. But NOT always a lower TOA.
There are quiet a few more situations where a ¼ GP can outperform a 5/8 wave and that is not only by adding the heigth the 1/4 wave.…that "thinking"would be quite inaqurate.
And don’t set your mind only to verticals. Think about horizontal antennas aswell…if you want to compare antennas and set a “standart” you must involve every possible antenna, not only mobile antennas.
The question asked is what do we want to measure? If that is Gain.
It is commen knowledge that a 5/8 wave has about 3,5 dBI Gain.
If you agreed on that, you agree on being wrong when saying “feedpoint” height.
That 3,5 dBI is under a certain angle isn’t it?
If you would compare that with other antennas with a different take off angle (but at the same feedpoint height) You will have a much larger difference. Though we already esthalished the gain of a 5/8 wave as a “known” fact.
You are speaking about the advantege of ground gain...oke...with the radiating center of the antenna of both antennas at equal distance from the earth that advantege of gain would be equal!
You can verify that by the fact people use stackmaster for a horizontal stack in order to change TOA.
Now, I can understand if one tests mobile antennas it is feedpoint height, as that would be practical as mentioned. And the tests will show the results everybody else will see when using it…however I do hope you understand that “practical reasons” are not always ..”fair”…
When we test antennas we do everything to get as close as we can to a "freespace" model. That would not be feedpoint heigth. As that wouldnt not give a equal groundgain...also the TOA can be completly different.
So either you should keep that last factor in mind and dont do DX test.
And finnaly, say you would have 2 antennas "sitting on the ground".
one is 1 meter long the other is 20 meter long. Both are bottum end fed.
The test antenna is a 1 meter high antenna placed at 10 meters heigth at a equal length away from horizontal distance from the two antennas.
The route a signal most travel from the two antennas under test are by far not equal.
I do not know if you ever heard of the Friis transmission formula..that tells is distance has influence on signal strength. And that is one of the things that is not equal with the same feedpoint heigth. Therefor i dont see how you can be correct.
If you place antennas at feedpoint height, exactly then people are giving bennifits to certain antennas.
Regards,
Henry
11 meter Dx antenna systemx
Last edited:
@ Marconi,
Yes i have tested some of those different things.
No i didnt find much noticable difference if you used only what a average CB would have.
As mentioned in other posts, the one with my vote would have : no matching system ...direct 50 ohms. No mather what matching system one uses there is some sort of loss.
Yes many manufacturers claim to have the best "matching" system.
You see where im going at ? with saying so that also agree on the loss that is present.
When looked at any mathcing system yes ofcourse you should go for the one that has the lowest loss (the same you watch with antenna coil Q).
Your question in regards to how much influence it has...well things can go very wrong at the feedpoint dont forget that!
But say we have a equal gain yagi one is 50 ohms one would be 25 ohms and fed by a gamma-match ...no you wont find much practicle difference.
The same with SWR, it is over exacurated. You can easily have a SWR 1:1,5 or so ...nobody is gonna notice any difference with that or 1:1,1 ...
But one is capaple of noticing all those small errors and loss together.
On the otherhand matching can be of serious influence. I know a "high quality" antnena manufacturer wich makes 70cm yagi"S using a t-MATCH. They have done there moddeling without that match. If you would include that match a drop of about 3..4 dB is noticable.
(not cause it s a lousy matching system or so..it is the physical dimension wich made that influence.). Tests have verified that.
You should place "matching" devices in 5/8 wave verticals, only for example to get a idea of bandwidth, and loss.
And for real live...well you already know a 5/8wave without a matching system would give serious problems.
The amount it influece Eznec will vary by what you use. And how you would insert things.
Ezenc has it limitation. For example a 1:8 balun or so can only be seen as a "perfect" balun...
Wich in real live ofcourse can be very differently!
Regards,
Henry
11 meter Dx antenna systemx
Yes i have tested some of those different things.
No i didnt find much noticable difference if you used only what a average CB would have.
As mentioned in other posts, the one with my vote would have : no matching system ...direct 50 ohms. No mather what matching system one uses there is some sort of loss.
Yes many manufacturers claim to have the best "matching" system.
You see where im going at ? with saying so that also agree on the loss that is present.
When looked at any mathcing system yes ofcourse you should go for the one that has the lowest loss (the same you watch with antenna coil Q).
Your question in regards to how much influence it has...well things can go very wrong at the feedpoint dont forget that!
But say we have a equal gain yagi one is 50 ohms one would be 25 ohms and fed by a gamma-match ...no you wont find much practicle difference.
The same with SWR, it is over exacurated. You can easily have a SWR 1:1,5 or so ...nobody is gonna notice any difference with that or 1:1,1 ...
But one is capaple of noticing all those small errors and loss together.
On the otherhand matching can be of serious influence. I know a "high quality" antnena manufacturer wich makes 70cm yagi"S using a t-MATCH. They have done there moddeling without that match. If you would include that match a drop of about 3..4 dB is noticable.
(not cause it s a lousy matching system or so..it is the physical dimension wich made that influence.). Tests have verified that.
You should place "matching" devices in 5/8 wave verticals, only for example to get a idea of bandwidth, and loss.
And for real live...well you already know a 5/8wave without a matching system would give serious problems.
The amount it influece Eznec will vary by what you use. And how you would insert things.
Ezenc has it limitation. For example a 1:8 balun or so can only be seen as a "perfect" balun...
Wich in real live ofcourse can be very differently!
Regards,
Henry
11 meter Dx antenna systemx
Last edited:
I agree with the Jazzsinger. Any situation where you change any of the parameters such as coax, pl plugs, where the coax is located along a building, its location in the environment and possible attenuation variables then you cannot possibly have a valid test. Just because the antennae are at the same height doesn't mean jack shit unless they are on the same pole using the same equipment as the previous test.
Only takes an impedance bump in coax, a pl plug that is slightly more efficent than another to entirely screw the tests up.
It has to be done on the same mounting pole with the same coax and plugs, rigs etc with a more reliable signal than SSB. Needs an FM station perhaps 40-50 miles away and if there isn't one then use someone mobile.
Only takes an impedance bump in coax, a pl plug that is slightly more efficent than another to entirely screw the tests up.
It has to be done on the same mounting pole with the same coax and plugs, rigs etc with a more reliable signal than SSB. Needs an FM station perhaps 40-50 miles away and if there isn't one then use someone mobile.