I paid 129 Euro +28 Euro postage on the 7th of May and it came after about 3 weeks. I put most of it together today, but there is a bolt+nut that goes on the bottom of the top hat shaft that is missing. I'll head over to a hard ware store and buy some nuts and bolts and sort it out. Its no biggie.It probably took longer to get here on account of the Chinise Communist Party Corona Virus Present to the world.
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ASTROPLANE best vertical antenna ever?
- Thread starter nosepc
- Start date
I saw this old thread bumped up and the subject has always been a favorite antenna of mine. I started to read the whole thing over, but it just put me to sleep. So, I got out my old files and got together some topics for discussion. Some of this has likely been discussed before and some of this is recent models that I've done long since these old days back in 2013.
Link for an old advertised gain report for Astro Plane.
https://www.rigpix.com/antennas/avanti_av101.htm
Below are some PDF files for Eznec models, and one for some comments I found on eHam, and one of an article in CB Magazine.
1. shows the AstroPlane at 36' feet over Average Earth with no Top Hat showing:
4.88 dbi gain at 30* degrees
4.42 dbi gain at 10* degrees, and this is close to the published reports.
2. shows the Avanti Astro Beam at 36' feet over Average Earth showing 7.72 dbi gain at 10* degrees, and rejection at -35.41 dbi at 5* degrees, with -31.45 dbi at 20* degrees. I could make the A/B show a better gain, but doing so reduced the rejection markedly, and I was looking to support what I have read about the AstroBeam antenna from the Patent and the article posted below...where the discussion was talking about the beams rejection and not the gain.
I also added an Azimuth, Free Space image for the Astro Beam model (looking down from above)...showing the great Rejection the Engineers noted for this Beam. This pattern image also agrees with the similar image noted in the published article in CB Magazine, August, 1970, "How to Make an Omni into a Beam," bottom of page 13 below.
3. shows the eHam Forum comments with some Avanti history.
4. again, in this CBM article posted in the PDF file below, talks about the Astro Beam and the great rejection it was making during Avanti's testing.
Some CB operators have commented over time, that the Avanti engineers did not know how the AstroPlane worked. IMO, that idea was taken out of context, an error again, because Avanti was discussing the Astro Beam rejection characteristics and how it worked, not how the Astro Plane worked.
Link for an old advertised gain report for Astro Plane.
https://www.rigpix.com/antennas/avanti_av101.htm
Below are some PDF files for Eznec models, and one for some comments I found on eHam, and one of an article in CB Magazine.
1. shows the AstroPlane at 36' feet over Average Earth with no Top Hat showing:
4.88 dbi gain at 30* degrees
4.42 dbi gain at 10* degrees, and this is close to the published reports.
2. shows the Avanti Astro Beam at 36' feet over Average Earth showing 7.72 dbi gain at 10* degrees, and rejection at -35.41 dbi at 5* degrees, with -31.45 dbi at 20* degrees. I could make the A/B show a better gain, but doing so reduced the rejection markedly, and I was looking to support what I have read about the AstroBeam antenna from the Patent and the article posted below...where the discussion was talking about the beams rejection and not the gain.
I also added an Azimuth, Free Space image for the Astro Beam model (looking down from above)...showing the great Rejection the Engineers noted for this Beam. This pattern image also agrees with the similar image noted in the published article in CB Magazine, August, 1970, "How to Make an Omni into a Beam," bottom of page 13 below.
3. shows the eHam Forum comments with some Avanti history.
4. again, in this CBM article posted in the PDF file below, talks about the Astro Beam and the great rejection it was making during Avanti's testing.
Some CB operators have commented over time, that the Avanti engineers did not know how the AstroPlane worked. IMO, that idea was taken out of context, an error again, because Avanti was discussing the Astro Beam rejection characteristics and how it worked, not how the Astro Plane worked.
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Marconi, I have not put the astroplane up yet. I have been too busy this year to play radio due to family commitments.
Hopefully I get some time in the future to do so.
I'm glad that I found an Astroplane to buy albeit a copy of one. You can't beat the classics.
Hopefully I get some time in the future to do so.
I'm glad that I found an Astroplane to buy albeit a copy of one. You can't beat the classics.
Oooops I forgot to mention about the construction comment.
The antenna is very light. As to its ability to withstand harsh weather conditions and high winds I would take the cautious approach and take it down in the event of a storm. Otherwise for the normally rainy weather we get here most of the time ( Its bucketing down now, as I type this) once the antenna is sealed watertight, then it should perform quite well.
The antenna is very light. As to its ability to withstand harsh weather conditions and high winds I would take the cautious approach and take it down in the event of a storm. Otherwise for the normally rainy weather we get here most of the time ( Its bucketing down now, as I type this) once the antenna is sealed watertight, then it should perform quite well.
BFI, if and when you get some time, maybe you could post the manual. If it doesn't show much detail, then maybe you could give me the exposed length dimensions, length and diameter, for the top hat, radiator, mount bracket, radials, and loop at the bottom. I would like to make a model of this Tagra idea for the A/P.
Thanks for the update and keep us posted if you get a chance to raise it up.
Marconi
Thanks for the update and keep us posted if you get a chance to raise it up.
Marconi
Shockwave says the A/P in free space has about 2.15 dbi gain and basically I agree, but............
My best Free Space (FS) model for the Old Top One (OTO), that I recently made using Loosecannon's dimensions, shows 2.33 dbi gain at 15* degrees in FS compared to the standard 2.14 dbi at 0* degrees for the vertical CFHWD. IMO, the A/P design skews the pattern due to the asymmetry in its design with the radiator being slightly off-set a bit to one side of the mounting bracket.
For sure the CF 1/2 wave patterns are not nearly as skewed as a typical 5/8 wave GP in Free Space...so I don't consider the A/P design a 5/8 wave antenna either.
This FS model (OTOw91"RADIATORw192"MwC FS) is the one I used to make the Real Earth model I posted below, and it does not show us the 4.46 dbi gain...like Avanti has advertised for years. Instead, it shows 3.60 dbi at 29* degrees and 2.92 dbi gain at 10* degrees above the horizon. This model in Free Space shows and Average Gain result = 1, which is suitable for typically good modeling results.
See DC9Q's post below where he links us to an old Avanti ad for the A/P.
Earlier in this thread I posted a model of the A/P with full length 1/4 wave radiator over Real Earth. It shows a similar gain to what Avanti erroneously advertised in the past at 4.46 dbi gain.
However, that model did not pass the Free Space Average Gain test, and the gain was overstated and apparently Avanti did not report their overstated error in gain, and the CB world love the high gain advertised.
This is the important point I'm trying to make evident with this post, IMO Avanti's reported high gain for the A/P was BS. A CFHW will not make that much gain.
I'm not surprised that Shockwave was surprised on installing his A/P antenna. I think the A/P, the Sirio New Top One, and the CTE Old Top One are all modified forms of a CF1/2 wave antenna and that may make a little difference in the performance that surprised Shockwave.
He also reported the A/P makes only 2.15 dbi gain. Donald do you remember where you got that info?
Some folks suggest this Sirio New Top One with a gamma match was not and A/P. I guess that is due to Sirio calling it a 1/4 λ Ground Plane. Other operators, over the years, have claim the A/P is a 5/8 wave antenna, and at one time I use to make the same claim. That said...the antenna pattern and the reported gain and angle do not support such ideas to make it a 5/8 wave IMO.
I understand some folks may be disappointed in these new results as compared to the model I posted earlier, showing almost exactly the same gain results as Avanti reported in their ads for years.
If I'm wrong then the A/P design has to be a 5/8 or better high gain antenna in spite of the facts that make it look like a CF 1/2 wave.
See models
1. in Free Space model showing the Average Gain Results = 1 which is perfect.
2. is over Average Real Earth model showing two images of the pattern that notes the maximum low angle gain and the maximum high angle gain. Also note the slight skewing in these patterns.
The A/P and the Old Top One designs show skewing due to their construction. This skewing in construction is not present with the Sirio New Top One antenna due to its design. I'll have to try and compare these two ideas to see how it might compare to the minor differences I saw in my Real World A-B testing a few years ago.
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Eddie,
i agree its not a 5/8wave in the conventional 1/2wave of wanted + 1/8wave of unwanted radiation in a linear radiator, its got a 5/8wave loop within its construction but its two transmission-lines in parallel when you add the mast/coax,
im not 100% on this idea
but the change in current at the feedpoint when you add the 1/2wave mast to the 5/8wave loop of an astroplane will be transmission-line mode current that causes radiation from the outside of the basket due to unbalance
in the same way a j-pole radiates from the short leg,
Avanti claimed higher gain for the sigma2 & higher still for the sigma4 so they did not say it had more gain than a 5/8wave,
it does have an advantage in height of current maxima when installed at the same height as 5/8waves & that's what the astroplane is all about,
maximising height of current maxima when you have maximum height restrictions,
how come A/S never did a hat loaded starduster.
i agree its not a 5/8wave in the conventional 1/2wave of wanted + 1/8wave of unwanted radiation in a linear radiator, its got a 5/8wave loop within its construction but its two transmission-lines in parallel when you add the mast/coax,
im not 100% on this idea
but the change in current at the feedpoint when you add the 1/2wave mast to the 5/8wave loop of an astroplane will be transmission-line mode current that causes radiation from the outside of the basket due to unbalance
in the same way a j-pole radiates from the short leg,
Avanti claimed higher gain for the sigma2 & higher still for the sigma4 so they did not say it had more gain than a 5/8wave,
it does have an advantage in height of current maxima when installed at the same height as 5/8waves & that's what the astroplane is all about,
maximising height of current maxima when you have maximum height restrictions,
how come A/S never did a hat loaded starduster.
Here is my model for the Sirio New Top One with a real gamma that is set over Real Earth at 36' feet. I did not tweak the gamma tap position or the capacitance value that I got from an older model I did sometime ago. The Average Gain results = 1, so the model is good to go and the feed point is in the right position, but the match is so so but workable.
I used the same 197" x 1.5" inch mast inside the antenna.
Notice the improved symmetry with this pattern and the slight increase in gain.
I used the same 197" x 1.5" inch mast inside the antenna.
Notice the improved symmetry with this pattern and the slight increase in gain.
When I made the antenna mast inside the radial cone area I extended it about 10" inches below the radial loop and the pattern was pushed up like a cloud warmer.
When I set the antenna mast to 48" below the loop, the match was good, and the gain an angle was was back to normal. I used 48" because I remembered the patent or the Manual told us to make sure the bottom was clear below the antenna by at least 48" inches. The gain did drop a little compared to the longer antenna mast that DB and I have been using with the A/P design. I was thinking that making the antenna mast longer, closer to a 1/2 wavelength was your idea.
Now, it looks to me like making the antenna mast longer than 48" below the radial loop is a waste of time. The Free Space model did report an AG result of 1.065 = +0.28 db inflated gain error however. When I adjusted the gain per the error noted, the model showed a little increase in gain over the model using the longer antenna mast.
If DB didn't come up with that idea, then it had to be GHZ24. But with that said, back in the days I tried to add his 4NEC2 details into Eznec and the model didn't work good, and I didn't see him using a long mast element inside the radial cone either. He did say his model was only close on specs however and I never went back and checked.
Possibly down another rabbit-hole over this design.
When I set the antenna mast to 48" below the loop, the match was good, and the gain an angle was was back to normal. I used 48" because I remembered the patent or the Manual told us to make sure the bottom was clear below the antenna by at least 48" inches. The gain did drop a little compared to the longer antenna mast that DB and I have been using with the A/P design. I was thinking that making the antenna mast longer, closer to a 1/2 wavelength was your idea.
Now, it looks to me like making the antenna mast longer than 48" below the radial loop is a waste of time. The Free Space model did report an AG result of 1.065 = +0.28 db inflated gain error however. When I adjusted the gain per the error noted, the model showed a little increase in gain over the model using the longer antenna mast.
If DB didn't come up with that idea, then it had to be GHZ24. But with that said, back in the days I tried to add his 4NEC2 details into Eznec and the model didn't work good, and I didn't see him using a long mast element inside the radial cone either. He did say his model was only close on specs however and I never went back and checked.
Possibly down another rabbit-hole over this design.