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Marconi, I will quote this sentence and propose a thought -
I do not read where W8JI has said the antenna w/o GP is either inefficient, nor in-effective, although one or the other is implied. I do read that he is saying the vertical 5/8 is unpredictable in its response/performance being without a GP. To this I propose that there is also a world of testimony. The A99 1/2ƛ, and the Imax2k 5/8ƛ both have those who've tried them and liked them, and those who've cursed them because they were dismal performers where they tried to use them. I believe they use the mast, or the coax, or surrounding elements, or some such for the missing part of the system. It seems to me that W8JI is making a case for the repudiation of the idea that antennas, particularly 5/8 verticals, which the Imax2k purports to be, do need a decoupling system in order to maintain stability of operation. He mentions the choke as one such device, but advocates for a sufficient radial GP network as the most effective means of achieving this when consistent performance is sought.

At least that was my read of it. I tend to think he's right.

I am not a software modeler. I can't speak to that. What I can say is that in virtually every instance of software modeling I've looked at people tend to forget that the model does not default to unpredictable variables so the modeling results tend to be the best potential - guidelines at best.

<blockquote data-quote="HomerBB" data-source="post: 281731" data-attributes="member: 8569">Marconi, I will quote this sentence and propose a thought - I do not read where W8JI has said the antenna w/o GP is either inefficient, nor in-effective, although one or the other is implied. I do read that he is saying the vertical 5/8 is unpredictable in its response/performance being without a GP. To this I propose that there is also a world of testimony. The A99 1/2ƛ, and the Imax2k 5/8ƛ both have those who&#039;ve tried them and liked them, and those who&#039;ve cursed them because they were dismal performers where they tried to use them. I believe they use the mast, or the coax, or surrounding elements, or some such for the missing part of the system. It seems to me that W8JI is making a case for the repudiation of the idea that antennas, particularly 5/8 verticals, which the Imax2k purports to be, do need a decoupling system in order to maintain stability of operation. He mentions the choke as one such device, but advocates for a sufficient radial GP network as the most effective means of achieving this when consistent performance is sought.At least that was my read of it. I tend to think he&#039;s right. I am not a software modeler. I can&#039;t speak to that. What I can say is that in virtually every instance of software modeling I&#039;ve looked at people tend to forget that the model does not default to unpredictable variables so the modeling results tend to be the best potential - guidelines at best.</blockquote>

[QUOTE="HomerBB, post: 281731, member: 8569"] Marconi, I will quote this sentence and propose a thought - I do not read where W8JI has said the antenna w/o GP is either inefficient, nor in-effective, although one or the other is implied. I [B]do[/B] read that he is saying the vertical 5/8 is unpredictable in its response/performance being without a GP. To this I propose that there is also a world of testimony. The A99 1/2ƛ, and the Imax2k 5/8ƛ both have those who've tried them and liked them, and those who've cursed them because they were dismal performers where they tried to use them. I believe they use the mast, or the coax, or surrounding elements, or some such for the missing part of the system. It seems to me that W8JI is making a case for the repudiation of the idea that antennas, particularly 5/8 verticals, which the Imax2k purports to be, do need a [B]decoupling[/B] system in order to maintain [I]stability[/I] of operation. He mentions the choke as one such device, but advocates for a sufficient radial GP network as the most effective means of achieving this when consistent performance is sought. At least that was my read of it. I tend to think he's right. I am not a software modeler. I can't speak to that. What I can say is that in virtually [B][I]every[/I][/B] instance of software modeling I've looked at people tend to forget that the model does not default to unpredictable variables so the modeling results tend to be the best potential - guidelines at best. [/QUOTE]

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