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My Latest Homebrew 5/8 Base Antenna

Don't let me corn'fuse :confused: you about the number of radials idea. I'm a firm believer (y) that adding more radials to my Marconi was the only way to go and possibly see some additional gain. There is more to my theory here than I'm telling here, :sneaky2: but I'll wait to tell more. It is so simple, :blush: I'm afraid you guys will laugh at me.

I've asked a buddy of mine to fix me another GPK hub for my A99 with at least 6 or 8 studs for 5/8 tubing both horizontal and at 17 degrees slanted down so I can try and emulate what the inventors of the Starduster did while developing their antenna.

Of course you are not likely to be able to get a multi-element beam to show as wide a bandwidth as a well designed and symmetrical vertical, but you might be surprised that you can get very close to 2 megs if you're willing to consider maybe compromising a bit.

The idea I suggested for checking the beam's bandwidth has nothing to do with how wide it is or isn't. The idea is to simply compare the before and after...and see if there is any significant difference to be noted with the vertical added to the mast above.

It is alright to follow another's lead on ideas, I often do the same. That is why I ask questions, even if it appears offensive to some.:headbang An example is: I thought you said my meaning was clear earlier, so I'll send you a video like I did for Booty Monster and splain' it all in pictures since my words aren't cuttin' it. This is not about you, I'm trying to figure out some of my ideas here, and you have the attitude and where-with-all to get-er-done, like nobody else on this forum, and I do mean nobody else. Hopefully you don't mind this approach.


BTW, in your BW curve with the 5/8 wave above the beam, are you able to note for us the full <2.0:1 SWR bandwidth in frequency? You tell us it is wider than the antenna when it was several feet above the roof, which I can easily understand, but your numbers don't jive in the high range and they stop at 1.3:1. If that is as far up as you can go, then how do you know for sure? I've seen curves that reach a certain point and almost shoot straight up from there on.
 
@ Tony: Thanks. The shaft on the bottom of the 5/8 is not metal. It is fiberglass, so there is no mechanical connection between the two antennas. I was speculating on the potential electrical/Rf bonding of the two. And I am not taking anything Marconi is saying to be negative. I solicited any/all input and he is generous enough to to give it the "Old Grandpa" treatment.

Thanks for joining the discussion.

@ Marconi: About the bandwidth; you are correct, I have taken the checking as far as I can with my DX88HL. I suppose I should have referred to the change in the SWR readings as apparently flatter across the tested range for greater clarity. I assumed the <2.0:1 was wider because it fell within my testable range before, and now I have not reached it because it is outside my testable range. Wrong thing to do. Even had I said apparently flatter across the tested range it would have been wrong. What is apparent is that was another case of someone seeing what they wanted to see. OOPS.
Before
28.755 ---------- 2.3:1
28.305 ---------- 2.3:1
27.855 ---------- 1.9:1
27.555 ---------- 1.4:1
27.405 ---------- 1.3:1
27.205 ---------- 1.1:1
26.965 ---------- 1.0:1
26.515 ---------- 1.3:1
26.065 ---------- 2.1:1
25.615 ---------- 3+

After
28.755 ---------- 1.2:1
28.305 ---------- 1.1:1
27.855 ---------- 1.1:1
27.555 ---------- 1.05:1
27.405 ---------- 1.0:1
27.205 ---------- 1.0:1
26.965 ---------- 1.1:1
26.515 ---------- 2.2:1
26.065 ---------- 2.9:1
25.615 ---------- 2.6:1
25.165 ---------- 1.9:1

Maybe I'll finally get a wee bit sharper than I am and read things properly in the course of time. With all the great help I get It should be sooner than later, I think . . .
 
I hope you don't mind.
swr_0002.jpg

swr_0001.jpg
 
Last edited:
MrSuburban said:
SWR is nice and all but where is the antenna actually resonant at?
I will have to get an analyzer to answer that very good question exactly. I am putting away my pennies until I can enough saved to buy one. . .
Smiley22-1.gif

Additionally, I am making it of 5/8 length for 11 meters. Without an analyzer, I am still relatively well assured that when I find my SWR match near or at the resonance I designed the antenna to be. If it were of the physical proportions of another wavelength, then i might have ned to be concerned that it was not resonant on 11 meters.

36 x .625 = 22.5 so my length is correct, and my match is good, and it performs well, so lacking better tools I move on and enjoy the fruit of my labor. I would like to know what an analyzer says about it, though.
 

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