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back on the astroplane

N

nfsus

Yeah its turned off, touch it
May 9, 2011
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Arkansas
alright, here i go again on the astroplane. there was a guy that i had talked to about a design he had made where everything was adjustable. tip to skirt. does anyone know or have a link for that design? im about to start another build and am curious about changing the diameter of the skirt ring by making it adjustable.

thanks
 

There was a thread created by ghz24 I think that had several models that were adjustable, the ap was one of them. I have made some for myself in the past as well, I'll look to see if I still have any of them backed up if you need one. Ghz and my models are for the 4nec2 software.


The DB
 
Im working off the idea that it's a 1/4 wave. At most a half wave. Which I doubt really. Anyway, I'm looking at a 20ft 1.5" mast over a metal roof. Then I'll start playing with the skirt. Skirts. Hahaha. I have the idea that I can use the roof for a ground plane effect and then adjust the skirt diameter to effect the to angle. If the skirt trick dont work, I'll start to adjust the length of mast below the skirt. It's just ideas
 
Here is a link to one of ghz24's posts with a modifiable model for the astroplane. As I recall it wasn't the correct dimensions, but most of the dimensions were changeable, so it should be a good starting point. It works with the 4nec2 software.

https://www.worldwidedx.com/threads/astroplane-best-vertical-antenna-ever.160317/post-445662

This antenna design simply doesn't fit with single end fed antenna lengths, although many people really do try and fit it in to said norms... Habit I guess.

Changing the skirt dimensions can change the angle of radiation for this antenna, but only when modeled in free space, and even then I don't think I've gotten more than a 5 degree change. I have never once seen modifying the skirt dimensions of this antenna change the angle of radiation over an earth.

As I recall about this antenna an mast lengths, there were some (very few) lengths that would shoot the angle of radiation sky high.


The DB
 
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Hello DB and Nfsus.

I tried in vain to find an Astro Plane design that produced a notable change in the TO angle. And, then I always had to adjust all the variables that GHZ24 notes in his 4NEC2 model.

Nfsus, don't give up on your project idea. You will likely have to adjust all the variables GHZ24 used in the model that DB posted above...just to retune the A/P after you change the loop diameter.

I recall DB doing testing of the radiator length top section of mast...that connects at the hub. I found lengths from 192" to 216" inches producing a little change in the gain as I made the length longer, but again never saw any change in the TO angle.

According to my Eznec models this antenna will require the lower ground mounted part of the mast to either be isolated from the top antenna section by 2"- 4", or you will have to add a 1:1 choke where the top antenna mast section and the ground mounted mast section would otherwise connect. (192" to 216" inches below the hub.)

I never recall seeing any change in the TO angle no matter what I did within this range.

I also imagine it would be a good idea to use a good antenna analyzer for this effort, but if not...then good luck.
 
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For some reason I've got it in my head that theres a good opportunity here to make gains through the adjustment. I read the patent. I get that they made a little bitty one and at about 100ft away blah blah ok. My ground, your ground, wherever, it's not going to be the same anyway. So I just figured if I can adjust the different aspects I can tune it to the instillation and not just throw it up and just change the spreader bar.
 
Sorry it's so grainy, that's just the camera vs the monitor goodies
 

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Check out this Eznec PDF file of my old Top One version of the AstroPlane...at 36' feet and it Free Space.

The pattern shown in your calculator must be several wavelengths high in order to show that much gain at that low of TO Angle.

BTW, this model has a full 1/4 wave radiator installed.
 

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i dunno. when you change the frequency on the program, the physical measurements change but the rest of the figures do not and are just a graphic. so im not sure whats up. ive not checked the measurements out yet. i didnt know that there was a program for it. ive got the adjustable skirt made up and the top element. tomorrow ill get the legs and mount pieced together. i have the skirt adjustable out to 58 inches, the top element stick is 8ft long with a cap hat. ill be able to adjust all day long.
 
nfsus said:
i have the skirt adjustable out to 58 inches, the top element stick is 8ft long with a cap hat. ill be able to adjust all day long.
Click to expand...

nfsus, if you can get the antenna back to a tune, after making changes to the various element lengths, tell me how you will know if the TO Angle has changed? I don't see the calculator helping in this case.

IMO, TO Angle is typically changed due to changes in antenna height over a real Earth model, and not a Free Space model just like DB has described above.

Good luck and keep us posted.
 
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Man you're right on target. The patent says that zero flare increased it 10 to 15 degrees so I'm thinking the inverse must be true. No that calc wont help on that at all and I'm still afraid I never have learned to eznec. If I can get it to tune after flaring it out? that's where I'm going to have to learn
 
nfsus said:
No that calc wont help on that at all and I'm still afraid I never have learned to eznec. If I can get it to tune after flaring it out? that's where I'm going to have to learn
Click to expand...
I agree the calculator won't help to produce a new pattern after you change the dimensions for any of the several variables you plan to make adjustable. I didn't read their comments on the Website, but when I saw the far field radiation pattern and follow up with some additional numbers...they could be misleading.

If you have the calculator software from SourceForge.net try and check to see if a change in the frequency variable will, in fact, change the dimensions given.

If that doesn't work, ?????????????.
 
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