That is good to know Homer. You were reading my mind. I was just about to look up where exactly you put your choke below the hoop, seriously. I was going to isolate the mast in my A/P model at the same point, and see what difference it made in my model that is working pretty good now that I've adjusted some mistakes and omissions. BTW, I think I'm about to give up on the idea of isolating the mast on the A/P, based on what I see happening to the match. However, there may hopefully be another way to improve stopping the RF on the mast/feed line.
Because of your testing noted above, and to confirm my suspicions that isolation is not the way to go, I think I realize now that my idea that isolation, using an insulator, would respond similar to the affects of using a feed line choke, maybe no-way-no. Now, with your information, I believe common sense would suggest that is wrong or it needs more consideration. Sorry for any confusion here, there is a distinction in there...that I'm really trying to make, believe me.
The feed line choke should be transparent to the system, but my models show that isolation affects the match, just like adding a mast to a model affects the match. So, I figure in the real world the same might be true. I'm just going to have to learn how to model a choke. I think it is possible with Eznec and maybe even effective at doing what is commonly believed.
I've just been looking at an old 2007, thread to refresh my memory of what has previously been said on the A/P subject. Look here, if you haven't seen it, you will be interested I think: http://www.worldwidedx.com/cb-antennas/26370-new-style-astro-plane.html
I'm testing some of the wisdom suggested in this thread. Based on my model and real world experience with the A/P, I believe some of it might have been off the mark a little bit.
I also have an old thread from 2010, noted below that is not too long back, but I can't find the thread still on the forum, and that is too bad. I found the older thread noted above, back in 2007 sometime, but this more recent one entitled "AstroPlane up and Testing" is not to be found. You will find this one interesting also. This guy, Starduster, came on for a while and could model, and was building a really nice and durable A/P styled antenna, and was experimenting on the best design. He is the one that really got me interested in learning to model, but he disappeared and I hated that. He was one of the few that didn't just give us words. Like you, he really did some work and showed us. Check it out, he was doing some of the very same things that you just did with your A/P, and that is remarkable. Too bad it's such small print, and ignore my notes. I have no idea what most of that means any more. If you can read his bandwidth charts, you will note there are frequency mistakes in his list. I just fix them in my mind.
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I just got through remodeling my working model of the A/P with a full 1/4 wave tip, and I'm in the process of considering how it responds...considering what has been said about it in the attachments above. More to come.
