Any Astro Plane Fans ?

[Riverman]

Riverman, I think maybe your friend might have done just what you said and spun his beam around to horizontal, but it wasn't an AstroBeam.

Pretty sure it was, Marconi. I had my Astro Plane at the time and was wanting an Astro Beam like his (I later got one but never tried mine horizontal LOL.) I remember thinking how weird his must have looked flat but never actually saw it. He was always trying different things.

A storm eventually wrecked his A/B and he simply took what was left and made an Astro Plane out of it. It did not have the top hat but still worked pretty well.

 

[Riverman]

He once tried mounting the Astro Beam at a 45 degree angle to see if it would work both vertically and horizontally. I don't recall the results. He hadn't had it up that way very long when the storm got it.

Sorry to get this thread off-track. My apologies.

 

[bob85]

i have no doubt they could be used horizontally and still work,

i could lay my astroplane down using a 90degree scaffold clamp if i wanted to,

it would be much easier & mechanically sound to use a horizontal dipole,

 

[Marconi]

Bob see it these two overlays and my explanation makes any sense?

Notice the asterisk (*) for both overlays shows the active antenna is the model with the green pattern.

I set the cursor at 31* degrees for the maximum gain point for the model in the 1st overlay pattern for the green color. I set the cursor at 14* degrees in the 2nd overlay pattern for the green color, at a point where all the models show the same gain 2.56 dbi.

This was done to call attention to the model with no ISO and no choke possibly producing as much or more gain when mounted the traditional way. The idea is to consider the RF above 14* degrees as beneficial and increasing as noted in these patterns...with more gain differences noted than we see at the lowest angle to the horizon.

That said however, with this simulation there may be no useful RF above 14* degrees. So, your idea regarding other issues with currents on the mast, must also be considered, and I suggest my idea here will possibly show more gain at a little higher point above the horizon.

The beam width for this design also looks to me to be a possible advantage in DX.

 

[Marconi]

Sorry to get this thread off-track. My apologies.

No problem for me 71.

 

[bob85]

Eddie,

I would be more interested in the red line that produces the most low angle gain & least mast/coax current & potential for rfi & noise,

in my experience that's the one that produces the strongest local signals & the best long haul DX ,

i have seen times when an antenna that is not as good for locals or for talking to usa & australia from here work stations in dx that i could not work on the sigma4 hybrid,

my i-10k got me straight into iceland first call several times,
i consider that short hop skip & the 10k walked over my locals all trying to work the same guy,
i have never worked iceland on the sigma from that location,

looking for an answer it turns out that a 5/8 not high above ground has its strongest lobe up at high angles with less
gain in the low angle lobe,

my own experience is higher angles are probably better for short hop skip at least some of the time,

but we know how mother nature does her own thing to throw up surprises from time to time like local imax 2000 whooping me on the 10k into your side of the pond.

Thanks

 

[Marconi]

i have seen times when an antenna that is not as good for locals or for talking to usa & australia from here work stations in dx that i could not work on the sigma4 hybrid,

On this count Bob, I know it is hard for most to believe, but I have to go back to my Starduster. With the locations and distances similar to those you note...I have a sense that my SD'r did it all very well.
In those days all my long distance contacts surprised me and I thought the contacts were simply due to favorable conditions and luck at the time. I also appreciate the issues you raise about such comparisons.

At some point I got my I-10K and almost immediately this forum started having DX contests. I recall hearing and talking to members on my I-10K all day and sometimes for a couple of days in a row. There were times I would switch back and forth between the SD'r and the I-10K and I did not think it strange to see little to no difference. I use to talk about those situations right here on the forum. I really like the I-10K but I always came to the same conclusion...the antennas worked about the same.

On the local scene out to maybe 60 miles my SD'r generally shows better responses on average of days and sometime weeks of recording signal reports. You've heard this before.

my i-10k got me straight into iceland first call several times,
i consider that short hop skip & the 10k walked over my locals all trying to work the same guy,

I know there were times I walked over other stations all around and sometimes at different locations in America. I have a video talking to 4040 in the Bay Area of California on my GainMaster and as far as I could tell nobody was able to get between us at the time. A few days earlier I did the same with my Starduster but the video did not save, so we missed that Watergate. I was proud to be making the contacts, but again I thought it was all due to luck and conditions. I never imagined that my antennas were any different from those around me. I figure they could hear and talk to the same stations I was.

looking for an answer it turns out that a 5/8 not high above ground has its strongest lobe up at high angles with less
gain in the low angle lobe,

I agree with you here 100%, I can see such comparison results with my models even though I don't recall being able to detect the difference using my radio. In those days for me it was probably a lack of understanding. While you, on the other hand, were apparently well read and maybe tutored on these subjects and knew what to look for. That is why I listen to you.

but we know how mother nature does her own thing to throw up surprises from time to time like local imax 2000 whooping me on the 10k into your side of the pond.

I can go along with mother nature as I noted above.

Thanks for the conversation.

Now I want to see how the A/P and the A/B works in the horizontal and that will be in another thread to see if a little ground gain gets me walking over all of my neighbors like you talk about doing.

 

[Riverman]

Now I want to see how the A/P and the A/B works in the horizontal and that will be in another thread.

Looking forward to that.

 

[bob85]

Eddie,
did you model the astroplane with NB's idea of no mast or coax inside the astroplane & the coax coming away @ 90degrees ?

i would not say im well read Eddie, i try to remember what i have read from respected sources & put it into practice, sometimes my interpretation of what they tell us may be off & sometimes its not.

 

[Marconi]

Eddie,
did you model the astroplane with NB's idea of no mast or coax inside the astroplane & the coax coming away @ 90degrees ?

The file below has 3 models.

1. an old NB'r model of the AstroPlane. It says it is to specs, so that might suggest I used some dimensions he posted, but I'm not sure what the model was about. I used it to modify to my best guess as to what he has in mind with this idea. That can be dangerous.

2. Is his model with no mast. I added a 18' foot feed line 90* degrees to the mount, that is also connected to a 36' foot feed line to Earth. This model has no chokes and we see currents on the feed lines.

3. Is the same model with two chokes added, one at the start of the 18' foot feed line at the mount, and another at the top of the feed line to ground where it connects to the 18' foot feed line.

I did nothing to try and get a better match for any of these models, but you will notice the 2 modified models, with and without a choke, are not showing a good match. Fixing the mast currents will not fix this mismatch.

I'm pretty sure you will agree that is what NB will likely find in a bad match if he does not have a mast inside the A/P antenna and extending below the hoop a bit. The tuner element below the feed point needs something to work against, and the mast inside the down elements is part of this design.

i would not say im well read Eddie, i try to remember what i have read from respected sources & put it into practice, sometimes my interpretation of what they tell us may be off & sometimes its not.

Maybe I used a bad choice of words, but in the example above you would probably have a minds eye idea of the problems NB'r is likely to face base on reading, experience, or getting a little tutoring at some point.

In my case the only way I would know to question NB'rs idea is via my modeling. That is what I meant when I suggested you were well read.

 

[bob85]

Eddie,

your model shows what I found when doing what NB suggested with washing line at a lower height above ground,
it is what I expected before I tested it because without the mast the loop impedance is high,

i have an idea of transmission-line currents in parallel with that high loop impedance but don't know how to prove or disprove it right now, im sure they are there but how do i prove it ?

imho calling it a mast is a misnomer, imho its part of the antenna,

I had two good elmers, Earnie & Ray,
both taught the city & guilds amateur radio course, they were & Ray still is a proper radio amateur that builds & modifys lots of their own gear,

I would sit in their classes not because I wanted to be a radio amateur, I was interested in how radio worked,
I never signed up to their courses, they let me join in because I was interested,

when I was a kid Earnie would cycle to my parents for a coffee some weekends,

he would bring watt meters dummyloads, dip meters, wave meters, in his rucksack & try to teach that crazy kid on the CB that was always fixing stuff making leyden jars, electroscopes spark gap transmitters blowing stuff up building & experimenting with antennas & trimming his coax how things worked,

they taught me there is much to learn, i will never know half of it, im still learning, its s low process,

the models you guys do help me understand & occasionally they have me baffled.

 

[Marconi]

it is what I expected before I tested it because without the mast the loop impedance is high,

That is what the model shows too.

 

[HomerBB]

@bob

"... i realise DB showed us low angle gain & vswr been higher with a longer mast but isolating that far below the antenna to test the idea would put too much load on my fiberglass isolator in high wind. "

A thing I often do to strengthen vertical masts or radiators is to use a section of PVC pipe that is larger over the weak joint(s). I do this everytime I build a dipole that will be mounted vertically with the coax running up through the lower tube.

 

[bob85]

That would work for a dipole or other lightweight antenna Homer,

The isolator i made is stronger than any CB antenna or pushup pole,
its strong enough for my modified sigma but not strong enough to hold 27ft of fat heavy mast & the astroplane in high winds without guying,

the law of moments dictates a very strong isolator that far down my mast for peace of mind.

 

[Oscar Goldman]

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