Any Astro Plane Fans ?

[Needle Bender]

Fun read, even with .Mr B's backhanded slams.
Gave me a chuckle.

And with regard to:
'Them 5/8s & .64s ain't nuthin' special'
and
'That AP is almost GOD!'
.banter...

Avanti .rated their AstroPlane @ 4.46dBi
Avanti .rated their AV-170 5/8 @ 5.14dBi

- And as far as the AP exhibiting a 'lower TOA' - well from the many 5/8 & AP models I've seen posted on this forum, it appears the 5/8 have their greatest gain in the 8°- 9° lobe whereas the AP appears to have its highest gain lobe up about 32°

unless...

YOU CAN'T ALWAYS TRUST THE MODELS

BTW Bob, and to clear up a possible faux-pas .on my part;

- When I wrote, "...I NEVER recommended a 1/4 wave..." I had not only forgotten I'd posted that 3-years ago as a description of what I did back in the late '70s, but I was also a bit miffed by you coming up with that old post as if I was touting a 1/4 wave of late for the mounting of the AP.

- Perhaps you inferred that I was being aggressive toward you when I was just quite surprised you seemed to think I'm currently encouraging a 1/4 wave mounting setup for the AP - after I'd been doing the opposite for quite some time to my memory by talking about full RF isolation from the bracket down, and for many months now.

I really never meant for you to feel "slammed" by that, it was written in a greatly surprised mood, not from a hotly defensive one.

- Apologies if that's what set you off.

So I'm scrapping the ropes idea, too hard to climb high enough to get a good pull angle without an ungodly amount of stress on the ropes, pulleys and ME, and just plain unnecessary extra work when I can easily buy a $12, 20' long, 2" x 4" and stick it atop my current mast with the AP bolted to the top for isolation.

I'll just drop the coax down the 2" x 4" with a CMC choke right below the bracket and every 6' or so below that, to prevent the coax from becoming the equivalent of a 1/4 wave, 1/2 wave, or any other relevant wavelength of metal mast. - and I can still pull the coax & chokes out 90° horizontally to a nearby tree if I feel it necessary.

The bottom 18" of the 2" x 4" when mounted to the existing metal mast on the house should elevate the base of the AP up to about 36' and should provide the info I'm .looking for; LOW SWR & Reactance.

I'll post the readings (from my MFJ-259B) later in this thread.

Modeling be damned, I still believe the AstroPlane is a complete .antenna. I can't imagine any reputable company relying on a CBer to 'finish' their antenna matching by using just the right length of mast, and I saw nothing in the manual recommending a 1/2 wave length mast.

After having just re-read the owner's manual, I see their only concern is that the ring be kept a minimum of 4 feet above & away from everything, requiring at least 12' of mast, and that the bracket be grounded, which I'll do via the coax shield when it gets to just outside the shack.

I admit my incredulity in reading so much god-like praise in this thread for an antenna I never liked, but that may very well have been because of the isolated 1/4 wave mast & choke I added, thinking I was helping because it eliminated our TVI issues, all the while perhaps killing it's best attributes.
We'll see.

If all goes as planned (does it ever?) I'll have the AP & 2" x 4" here in a week, two at the most.

Oh the anticipation...

 

[Riverman]

New to the forum, but not new to building or testing antennas. I built an astroplane a couple of months ago, and played with The hoop and top element size and lengths.
If there is anything you guys need to know about my build, please feel free to ask.
Thanks

Hi, Oscar. Welcome!
How about looking over this entire thread and sharing any thoughts you have? That would be helpful since you have experience with the antenna. All opinions are welcomed.

 

[Oscar Goldman]

Hi, Oscar. Welcome!
How about looking over this entire thread and sharing any thoughts you have? That would be helpful since you have experience with the antenna. All opinions are welcomed.

Will do later tonight when I have more time.

 

[The DB]

- And as far as the AP exhibiting a 'lower TOA' - well from the many 5/8 & AP models I've seen posted on this forum, it appears the 5/8 have their greatest gain in the 8°- 9° lobe whereas the AP appears to have its highest gain lobe up about 32°

Did you seriously post that?

Wow.

I don't know where you got that AP models showing a 32° angle of radiation, but it wasn't from any model I posted, and I don't recall any of Marconi's models showing that either, and between the two of us that will by far be the majority if not nearly all at least in this thread. If you include Marconi's models from other threads, that will likely put the two of us at over 90% of the models of the AP posted on this forum.

The only thing I can imagine that would cause a 32° angle of radiation is if one of us was showing a worst case scenario, which wouldn't be a fair comparison to a best case scenario, or even a regular model, of another antenna, would it? Long story short, this is nothing but a BS claim, period, end of story.

I can show you almost any antenna with whatever angle of radiation I want, it isn't even hard to do, you simply change the height of the antenna. That is it, no voodoo or anything strange, the higher the antenna the lower the angle of radiation. Because of this, antennas do not have a single angle of radiation, so any claim that any one antenna will always have a, say, 8° to 9° lobe regardless of the circumstances only shows how much you don't know about what you are talking about. If you want I can post an AP with an angle of radiation of 2° to demonstrate this.

For example, here is an image that I posted I don't know how many pages ago that directly shows a comparison between the AP and the I-10k, and this I-10k model includes a matching system and full tuning, so it is a direct antenna to antenna comparison. I should also point out that the AP is mounted at two different heights in this comparison, one with the same tip height as the I-10k and the other at the same mounting height.

So I will leave it to you to tell me which AP is mounted at the same tip height as the I-10k, actually I'll give you a hint, its the one with more gain than the I-10k and the same angle of radiation...

NOTE: As I pointed out when I posted this initially, the green line model is under reporting its gain. If you want to know more go back and dig up the original post.

The only other thing I can think of is you are referring to models I haven't seen and know nothing about, and with all due respect, that isn't very likely.

I'll just drop the coax down the 2" x 4" with a CMC choke right below the bracket and every 6' or so below that, to prevent the coax from becoming the equivalent of a 1/4 wave, 1/2 wave, or any other relevant wavelength of metal mast

If you bring it through the basket, I would recommend less than six feet per choke. Remember when you tried to model a quad then build it? Why was their such a big difference in length from the model that didn't factor in the covering on the wire used? In the area of the basket I would go more like two or three feet per choke until about five or six feet below the ring to avoid an issue with the VF caused by the material on the outside of the feed line.


The DB

 

[The DB]

New to the forum, but not new to building or testing antennas. I built an astroplane a couple of months ago, and played with The hoop and top element size and lengths.
If there is anything you guys need to know about my build, please feel free to ask.
Thanks

Welcome to the forum.

At this point I would be more interested in your thoughts and opinions on the antenna in question.


The DB

 

[bob85]

NB

read the patent again,
they tell us what happens when the mast is shorter than about 1/4wave below the hoop,
I talked about it years ago on here with Eddie when i thought it was possible to manipulate takeoff ange by shortening the mast below the hoop,

It should work with just the coax for a conductor,
i expect impedance to be higher than it is with the 1.5" mast due to the increased spacing & change in charge density on the center conductor increasing Zt ,
but not in the hundreds of ohms like the antenna without any conductor where the mast should be,

I don't think anybody here has made a model with a 1/2" or less diameter mast to simulate your test.

I don't think it will work correctly if you choke the coax inside the basket IF the choke is effective,

the factor that determines low angle gain most is height of current maxima above ground, on that score the astroplane has them all beat but its not GOD like, its physics

smart folk will tell you theres nothing special about 5/8waves once you realise why they produce more gain than a 1/2wave on the same pole.

 

[bob85]

welcome OSCAR,
i would be interested in what you found when building the astroplane and altering it from original measurements.

 

[Needle Bender]

...I don't know where you got that AP models showing a 32° angle of radiation...

NOTE: As I pointed out when I posted this initially, the green line model is under reporting its gain. If you want to know more go back and dig up the original post.

...So I will leave it to you to tell me which AP is mounted at the same tip height as the I-10k, actually I'll give you a hint, its the one with more gain than the I-10k and the *same angle of radiation*...

The DB

Well, admittedly I've been unable to spend the hours on here that I'd like to, as I'm helping two different friends move and have a lot on my plate right now, plus am the only person in another friend's life whom he has to help transport him back & forth each day to his cancer treatments, so DB, yes I flew a bit too quickly through the last few pages and mistook Marconi's "Old Top One" models for being anywhere near close to an AP.

And I simply don't have the time to go back through possibly hundreds of posts in multiple strands to play hide & seek with one of your older posts to find out how much you handicapped the model showing overlays of both the AP & I-10K in favor of the AP, (though I can't imagine a better, more productive & enjoyable way to use up several hours) but thankfully I don't need to since Avanti did it for us:

Avanti .rated their AstroPlane @ 4.46dBi
Avanti .rated their AV-170 5/8 @ 5.14dBi

...so according to Avanti, the 5/8 beats the AstroPlane ( with the SAME pattern, according to you*) by about 2/3 dB (.68dB)

 

[Marconi]

If there is anything you guys need to know about my build, please feel free to ask.
Thanks

Oscar, how is your antenna performance and compared to what?

What is your <2.00:1 SWR bandwidth is?

 

[Oscar Goldman]

When I first built it according to the factory manual with the capacitance hat, It works very well with about 300khz of bandwidth between the 1.5 to 1 points.
I wanted to get it a little wider than that, so I removed the cap hat and put on a straight tubing section.
The bandwidth now covers 600khz between the 1.5 to 1 points. Then I played with the ring diameter from 31 inches down to 26 inches, anything larger than 29.75 the bandwidth went back down. when I went smaller down to 26 inches the performance took a dive.
I have it ground mounted on a 25 foot mast, that puts the top at 32 feet. I mounted a Antron 99 60 feet away, with the top at the same height as the AP and the A99 was around 1 to 2 s-units weaker than the AP. Also the AP has less noise
These are just my basic test findings

 

[Oscar Goldman]

Welcome to the forum.

At this point I would be more interested in your thoughts and opinions on the antenna in question.


The DB

I like the antenna very much since I built it.
It's compact size and light weight make it a good choice.

 

[Marconi]

I wanted to get it a little wider than that, so I removed the cap hat and put on a straight tubing section.

Did you measure your BW with an SWR meter at the end of your working feed line?

Or did you use an analyzer?

I made a similar full 1/4 wavelength antenna out of my Old Top One (OTO) mounted about 42" feet high. The radiator was about 87.5" inches long overall with 46" x 0.625" and 41.5" x 0.50" inches to reach resonance at 27.205 mhz.

My 1.50:1 SWR bandwidth difference using my inline meter was 2.10 mhz for the full 1/4 wavelength and 1.91 mhz for the stock OTO. Less difference but not as much. Both our results agree with the Patent on BW however.

 

[The DB]

Well, admittedly I've been unable to spend the hours on here that I'd like to, as I'm helping two different friends move and have a lot on my plate right now, plus am the only person in another friend's life whom he has to help transport him back & forth each day to his cancer treatments, so DB, yes I flew a bit too quickly through the last few pages and mistook Marconi's "Old Top One" models for being anywhere near close to an AP.

OK. I suggest you should be careful of such claims in the future.

And I simply don't have the time to go back through possibly hundreds of posts in multiple strands to play hide & seek with one of your older posts to find out how much you handicapped the model showing overlays of both the AP & I-10K in favor of the AP, (though I can't imagine a better, more productive & enjoyable way to use up several hours) but thankfully I don't need to since Avanti did it for us:

...so according to Avanti, the 5/8 beats the AstroPlane ( with the SAME pattern, according to you*) by about 2/3 dB (.68dB)

I would say that Avanti's gain data would match both antennas being mounted at the same mounting height. If that is the case, the model you are falsely accusing me of handicapping was a different story all together. With that model, I compared it to a 5/8 wavelength antenna as the Astroplane patent said the Astroplane antenna should be mounted, and low and behold, as per the patent, the Astroplane had a higher gain. If you think following what the Astroplane patent says how one should mount this antenna being used in a comparison model (and by extension getting a result that is also in line with what the Astroplane patent says will happen) is "handicapping" then with all due respect, I disagree.

I guess this needs to be said. When it comes to modeling, I DO NOT HANDICAP MY MODELS, EVER. I take offence to this accusation.

The best part? You, who has claimed multiple times that you don't agree with the modeling results for this antenna, are now accusing someone who modeled this antenna of "handicapping" this antenna over another? That sounds like your trying to have your cake and eat it to...

Yes, I think the Astroplane antenna has an interesting design, and I think I might have a chance of learning something about antennas in general from it, but that is not a reason for me to handicap this antenna in a comparison with another. If anything that is a reason for me to want as fair comparison as I can get...


The DB

 

[Marconi]

Did you seriously post that?

Wow.

I don't know where you got that AP models showing a 32° angle of radiation, but it wasn't from any model I posted, and I don't recall any of Marconi's models showing that either, and between the two of us that will by far be the majority if not nearly all at least in this thread. If you include Marconi's models from other threads, that will likely put the two of us at over 90% of the models of the AP posted on this forum.

Hey guys compare the links below and I think you will see DB and Needle Bender are comparing apples and oranges.

http://hittman.us/pictures/6-10-17/ap-10k-comp.jpg

Any Astro Plane Fans ? you will have to open the PDF file in this link.

The only thing I can imagine that would cause a 32° angle of radiation is if one of us was showing a worst case scenario, which wouldn't be a fair comparison to a best case scenario, or even a regular model, of another antenna, would it? Long story short, this is nothing but a BS claim, period, end of story.

DB, I think you both are referring to two different models. IMO this is somewhat similar to what you suggest above. Except I'm not so sure the worst case scenario produces as much difference as some report.

I just went through some various simulations of my OTO model with Bob on these very issues and there just wasn't much of a difference when all is said and done. That said however, I do appreciate the other problems that Bob has suggested that must be considered as well and I don't ignore the old adage that "...ever little bit of advantage counts."

Since you did not post an image of your model, only the pattern overlays, I assume your models above are isolated (ISO) at the base of the mast inside the antenna and below the bottom hoop.

My models in the link I posted are typical installs with a full mast supporting the antenna, no isolation. One model is without choke and one with a choke which mitigates the currents on the mast.

I know that Avanti published a gain of 4.46 db over an isotropic source and the model in my link above shows a maximum gain close to 4.46 dbi at 32* degrees. IMO this is similar to Bob's ideas that Avanti puffed about their antenna performance just like other manufactures are prone to do.

I cannot explain the difference in antenna gain between our models for the examples above, but I have models that produce similar gains to yours when I use two wires for the hub instead of the 5 wire design I use...that simulates the A/P antenna's hub at 2.50" x 6" inches.

DB, maybe when you get some time we might discuss these gain differences.

 

[Oscar Goldman]

Did you measure your BW with an SWR meter at the end of your working feed line?

Or did you use an analyzer?

I made a similar full 1/4 wavelength antenna out of my Old Top One (OTO) mounted about 42" feet high. The radiator was about 87.5" inches long overall with 46" x 0.625" and 41.5" x 0.50" inches to reach resonance at 27.205 mhz.

My 1.50:1 SWR bandwidth difference using my inline meter was 2.10 mhz for the full 1/4 wavelength and 1.91 mhz for the stock OTO. Less difference but not as much. Both our results agree with the Patent on BW however.

I tested it with an analyzer, then backed it up with my Yaesu ys-60 watt meter. Also the SWR meter on my 1000MP agrees with the results.