Re: Dipole antenna with Low Z0 feed point Impedance
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Bill,
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Single band or multi? Because the 1:2 transformer (also use a ferrite choke) only matches the feed point essentially on one band (there will likely be some higher-order sorta-matches in there, too), I always just put up the attic loop or dipole and put an LDG RT-100 (or similar) at the feed point. Then, DC to Daylight. Interesting question, though. I want to know the answer as well. :) Regards, Kirk, NT0Z My book, "Stealth Amateur Radio," is now available from www.stealthamateur.com and on the Amazon Kindle (soon) On Friday, November 8, 2024 at 11:54:24 AM CST, Bill WA2WIO <sla@...> wrote:
Using a VNA to measure dipole antenna feed point characteristics has been discussed. I believe this is a little different twist. I have an attic mounted 1/2 wave dipole antenna with a 20-25 ohm Z0 at the feed point. I expected this because of the 12 foot attic mounting height, non-linear non-symmetric shape, near by structures, poor ground effect, other constraints, etc. Having confirmed this, how to best match this dipole's Z0 of 25 Ohms to a 50 ohm coax line is now the challenge. Would a 1:2 UnUn be appropriate? 1:2 BalUn? If so, what would this UnUn / BalUn look like? I have seen 2:1 commercial units available. The input and output connectors are for 2:1. I have not seen one with the connections setup for 1:2. If this is a viable are there any recommended commercial sources for it? I would then use the VNA to verify results. Thoughts and suggestions? Thank you. Bill WA2WIO |
Kirk Kleinschmidt, NT0Z