To 7/8 or NOT to 7/8, that is the equastion

[Marconi]

Are you suggesting I make these mast changes by removing length at the bottom instead of at the top...keeping the mast connection at the antenna's original height of 45' feet?

If so, it looks like it will show small changes in results unless maybe the model is in Free Space.

 

[Needle Bender]

Are you suggesting I make these mast changes by removing length at the bottom instead of at the top...keeping the mast connection at the antenna's original height of 45' feet?

If so, it looks like it will show small changes in results unless maybe the model is in Free Space.

Yes that's correct. As if it was installed atop different height houses but always 45' to it's base.
Maybe then try the same multiple lengths but while making the mast part of the antenna to see what the currents would do differently.

 

[Marconi]

Here are the models with different length mast, but remember in a similar situation in the real world, and assuming you use the same feed line, you will have a feed line that will replace the missing mast portions, and for the most part everything will remain close to the same.

If you want to get a real close up view of the cluttered patterns then use the zoom feature with this PDF file. It will get a bit grainy, but you can probably see that the 27' foot 3/4 wavelength mast length and the *Primary model are 1 & 2...but to me you could never tell a difference in any of these signals just using your radio.

IMO, anybody with one of these CB verticals antennas that sees a 1 or 2 Sunit difference in signals on their radio and is concerned with line length...is like I've heard described. "...there is something else going on that makes the difference."

IMO and within reason a well constructed CB vertical antenna system, differences due height make the biggest difference...if there are any differences. (edit) I don't see much differences in my real world CB antenna signals either.

 

[Needle Bender]

Here are the models with different length mast, but remember in a similar situation in the real world, and assuming you use the same feed line, you will have a feed line that will replace the missing mast portions, and for the most part everything will remain close to the same.

If you want to get a real close up view of the cluttered patterns then use the zoom feature with this PDF file. It will get a bit grainy, but you can probably see that the 27' foot 3/4 wavelength mast length and the *Primary model are 1 & 2...but to me you could never tell a difference in any of these signals just using your radio.

IMO, anybody with one of these CB verticals antennas that sees a 1 or 2 Sunit difference in signals on their radio and is concerned with line length...is like I've heard described. "...there is something else going on that makes the difference."

IMO and within reason a well constructed CB vertical antenna system, differences due height make the biggest difference...if there are any differences. (edit) I don't see much differences in my real world CB antenna signals either.

Whoa, a full dB lost at the low angle, if the mast is right at a 1/4 wave long.

What's odd is I would expect the primary (27' mast) to be identical to the 3/4 wave (also 27') but they're not... WTH? (H = Heck, - more polite )
What if you tried one more, say the 1/2 wavelength, but tell the model that it's part of the antenna then use a 1/2 wave mast (not "antenna") as primary, both at 45'

... and maybe a 2nd at 36'?

 

[Marconi]

Whoa, a full dB lost at the low angle, if the mast is right at a 1/4 wave long.

What's odd is I would expect the primary (27' mast) to be identical to the 3/4 wave (also 27') but they're not... WTH? (H = Heck, - more polite )
What if you tried one more, say the 1/2 wavelength, but tell the model that it's part of the antenna then use a 1/2 wave mast (not "antenna") as primary, both at 45'

... and maybe a 2nd at 36'?

These results are listed by dbi values...not db and all the differences are so small to be insignificant just using a radio.

Just in case there is any misunderstanding about what *Primary means.

An overlay is made from the pattern for a particular model and that model is called the Primary model. The title (description) is right below the pattern.

If I make an overlay the other model(s) will appear at the top left hand side of the page listed right below the notation (*Primary).

NB, the 27' foot model simulates the 3/4 wavelength model your requested, and nowhere did I show this 27' foot model as a Primary.

The Primary in this project was the NV4K with a full length mast 45' feet long and connected to the Earth. It is the first model image in the PDF file I posted, and the overlay was the cover above it.

Below is an image of the 9' foot model as the Primary in this case being the model with the least gain. I added an overlay of the 27' foot model with the best antenna gain in the group.

This shows a difference of about 1 dbi difference, and IMO that is not much compared to a db or and Sunit. If you were working this antenna, and talking to another with this 9' setup and one with the setup with a 27' foot mast...I doubt you could tell any difference.

 

[Needle Bender]

In addition (to your already busy schedule, no doubt) I have a funky weird idea...

If you do a 27' mast but add a 2nd cone a full 1/2 wave tall, not just a 1/4 wave like the original, (right side up like the original) right at the 1/2 wave point below the base of the original antenna, so the bottom additional cone top ring would be almost even with the antenna base - I wonder if it might not change the pattern considerably but capturing the non-constructive 1st 1/4 wave below the antenna, inverting it to become another commensurate constructive-current radiator?

These results are listed by dbi values...not db and all the differences are so small to be insignificant just using a radio.

Just in case there is any misunderstanding about what *Primary means.

An overlay is made from the pattern for a particular model and that model is called the Primary model. The title (description) is right below the pattern.

If I make an overlay the other model(s) will appear at the top left hand side of the page listed right below the notation (*Primary).

NB, the 27' foot model simulates the 3/4 wavelength model your requested, and nowhere did I show this 27' foot model as a Primary.

The Primary in this project was the NV4K with a full length mast 45' feet long and connected to the Earth. It is the first model image in the PDF file I posted, and the overlay was the cover above it.

Below is an image of the 9' foot model as the Primary in this case being the model with the least gain. I added an overlay of the 27' foot model with the best antenna gain in the group.

This shows a difference of about 1 dbi difference, and IMO that is not much compared to a db or and Sunit. If you were working this antenna, and talking to another with this 9' setup and one with the setup with a 27' foot mast...I doubt you could tell any difference.

I still think a dB is a dB! That's more than the difference between an I-10K & the NV4K that Shockwave (For the brothers that aren't here) claimed the operative difference to be (2dB) and your plot showed less than 1dB between those two.

OK, I see I misread the primary length as a 27' mast.

Could you possibly use that last plot and overlay an NV4K with no mast, as if floating at 45'?

 

[Marconi]

Could you possibly use that last plot and overlay an NV4K with no mast, as if floating at 45'?

Yes, but I don't think you will like it.

To be clear you are asking me to remove the 9' foot mast from the model, right?

 

[Marconi]

Could you possibly use that last plot and overlay an NV4K with no mast, as if floating at 45'?

I think this is what you asked for.

 

[Needle Bender]

Yes, but I don't think you will like it.

To be clear you are asking me to remove the 9' foot mast from the model, right?

I just wanted you to add & overlay the NV4K w/o mast to the last plot with the two that were there in the last plot.

 

[Needle Bender]

These results are listed by dbi values...not db and all the differences are so small to be insignificant just using a radio.

Just in case there is any misunderstanding about what *Primary means.

An overlay is made from the pattern for a particular model and that model is called the Primary model. The title (description) is right below the pattern.

If I make an overlay the other model(s) will appear at the top left hand side of the page listed right below the notation (*Primary).

NB, the 27' foot model simulates the 3/4 wavelength model your requested, and nowhere did I show this 27' foot model as a Primary.

The Primary in this project was the NV4K with a full length mast 45' feet long and connected to the Earth. It is the first model image in the PDF file I posted, and the overlay was the cover above it.

Below is an image of the 9' foot model as the Primary in this case being the model with the least gain. I added an overlay of the 27' foot model with the best antenna gain in the group.

This shows a difference of about 1 dbi difference, and IMO that is not much compared to a db or and Sunit. If you were working this antenna, and talking to another with this 9' setup and one with the setup with a 27' foot mast...I doubt you could tell any difference.

After re-reading your above post (my emboldening & lightening of color for clarity) I was left wondering how any dB lost or gained is different from any other, regardless of the reference dB, as long as both antennas, or design plots, being compared use the same reference?

If antenna A bests antenna B by 2dBi, it should also best it by 2dBd, 2dBgp or whatever reference is employed during the time of testing or plotting.

...or am I missing something?

 

[Needle Bender]

Well, having fallen into a brief financial crisis, forcing the sale of many items including the still new-in-box NV4K, I'm now close to rebuilding the Saliute into an NV4K.

I just finished re-reading this entire thread and reviewed all your sim plots, (Marconi) and am newly convinced to duplicate the NV4K cone & radiator length, then after a week or two of logging signal strengths, extend it to the 29' height and re-test.

I'll be swapping out from a 22' 9"-long, .64-upgraded MacoV58, so the results should be enlightening.

Apologies all around

for several months of leaving y'all hanging

 

[Marconi]

NB, how are you coming along on your Saluite rebuild?

 

[M0GVZ]

I'll be swapping out from a 22' 9"-long, .64-upgraded MacoV58, so the results should be enlightening.

Assuming no other changes than the antenna I think you may find them quite disappointing as in none you can detect.

I think it may be time for me to do a comparison video and put this one to bed. I did a comparison between a 1/4 wave 2m antenna and a 5/8 2m antenna to a repeater 55 miles away from where I live and found no noticable difference. I now have a 1/4 wave 2m antenna on my car. Going on the claims made on this forum about the differences between various 1/2, 5/8 and .64 wave antennas I should have been seeing several S points yet not one was noticed.

If you're not going to see a difference between a 1/4 wave and a 5/8 wave you're not going to see a difference worth a toss between the various 1/2, 5/8 and 3/4 wave vertical antennas you can buy, certainly not one worth spending money on if performance improvement is your aim.

And I've seen enough CB antenna comparison videos on Youtube with claims of "is a 1/4 of a S point better" claims to feel vindicated in this point of view.

Antron A99 vs Sirio Gainmaster. Pretty much exactly what I expect.

 

[Marconi]

Conor, for years I have been reporting about the same results, and showing the same on some of my videos. Your reports were done better however. Your signals we saw and heard both TX and RX signal reports, and that is better.

What a hobby!

 

[M0GVZ]

Conor, for years I have been reporting about the same results, and showing the same on some of my videos. Your reports were done better however. Your signals we saw and heard both TX and RX signal reports, and that is better.

What a hobby!

Not my video but one I have bookmarked for such conversations.