Base Bob's Avanti AstroPlane model

[bob85]

vector comes 3rd when mounted at the same tip height Homer,
1/2wave is a little better than 5/8 at same tip height with the astroplane out in front,

my mast below the hoop is a little long according to Eddie & about right according to DB,
i don't know what diameter mast DB used or what height above ground,

 

[Marconi]

If you are happy the models are pretty accurate i think im right in rating the astroplane at least as good as my 5/8waves Eddie,

Sometimes I don't have confidence that I'm getting good results, primarily, with my 5/8 wave models. IMO they need a physical match, and the 5/8 wave model does not respond easily.

I can model a physical matching device in a fashion and I can get a good match, but the models always seems to perform poorly. Sometimes I think such a model is doing better and I'll post it, but looking at it later...I see some flaw and I wish I had not posted it.

 

[HomerBB]

vector comes 3rd when mounted at the same tip height Homer,
1/2wave is a little better than 5/8 at same tip height with the astroplane out in front,

my mast below the hoop is a little long according to Eddie & about right according to DB,
i don't know what diameter mast DB used or what height above ground,

I had a difficult time distinguishing between the two red colors on my cell phone. Went back over them. You are correct when I looked at the asterisks more carefully.
Goes to show how the AP has the advantage with its higher current maximum in relation to its tip.
Perhaps the .625 does least well due to the inverse current in lowest 1/8^ of the vertical?

 

[Marconi]

Perhaps the .625 does least well due to the inverse current in lowest 1/8^ of the vertical?

I figure the same, Homer.

Bob, the PDF shows my iterations from 197" mast to 224" inches. I hope this handwritten comes out clear enough to see the numbers. As usual, I don't see as much difference as I imagined.

All the Average Gain results were overstating the gain. When I fixed the AGT = 1...the gain went down the value of the AGT correction factor. So, the highest gain reported in the longer mast never went over 2.31 dbi gain, and these models were in Free Space so I could see the smaller details in the AGT.

I hope you weren't looking for a couple of db or more gain.

When I was doing the scans earlier and I got to 196" inches the AG correction factor was overstated 0.04 db. When I fixed the model to a 197" inch mast the AGT value dropped to 0.00 db and I figured I had reached a tipping point. I imagined the mast was at a resonant length for 1.50" aluminum.

But I was just thinking why...out loud!

 

[Marconi]

Goes to show how the AP has the advantage with its higher current maximum in relation to its tip.

Homer, do you think maybe this might be another consideration, like Bob makes, for why Avanti depicted their antenna like they did to the buying public? I would think it would take a real antenna expert to figure out what we see here from this little antenna by Avanti. IMO, this is amazing and I did not expect the nice difference...and for an antenna that is real quite too.

I had my New Top One up as far as I could get it with a 10 foot extension on my 40' foot pushup pole and that bugger barked.

 

[Marconi]

Well, men, when I was scanning the A/P model earlier this evening I saw something unusual, but I decided to press on and finish so I wouldn't forget the point I was trying to make for my post above.

I just went back and found the model was showing Average Gain issues and the model was not made with control of the AGT = 1. I started with a Free Space model, and it was fine but I forgot to tune the antenna when I added losses back. I also posted an A/P model that was noted with Bob's name in the title. It too shows some very good gain, but I haven't checked it yet.

I'll try to fix it tomorrow. Sorry!

 

[bob85]

I don't expect anything like 2db gain difference between any of the usual antennas in free space Eddie,

most of the difference seen between antennas is due to height of current maxima and the antennas not been installed to minimise cmc on mast and feedline,
that includes the a99 dummyload blead stick people keep telling us about,

i do expect the astroplanes extra 4ft height of current maxima to make some difference when mounted over real earth with obstructions around the antenna as depicted in the astroplane ad,

you have seen with your own eyes the effect of not having the antenna clear of houses or other obstructions that you cannot model,

its under those conditions that height has the most effect on signal,

 

[Marconi]

I don't expect anything like 2db gain difference between any of the usual antennas in free space Eddie,

I was just kidding with you, Bob.

most of the difference seen between antennas is due to height of current maxima and the antennas not been installed to minimise cmc on mast and feedline,

Of course!

 

[Marconi]

OK folks, I tested every model in the PDF file below, and posted the Average Gain Test for each model, and they all = 1.

Bob, I made two A/P models:
1. is with 197" x 1.50" inch mast below the FP hub.
2. is with 216" x 1.50" inch mast below the FP hub.

There are several overlays showing each model as active.
Then each model with the AGT in Free Space as the front page.

The CF Dipole is there for comparison.
The 0.625 wave is a basic model with no matching.

I have work to do on my 5/8 wave models with a physical match.

Sorry for messing this up earlier.

 

[HomerBB]

Hmm. . .
Back to the Nv4k on top of the pile.