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On Fri, 21 Apr 2017 18:28:32 +0100, Jeff wrote:
No. The above antenna is tuned for 144 to 148MHz. Marine band transmit is from 156.0 to 157.5Mhz transmit, and 161.975 to 162.6Mhz for AIS and weather. You might be able to retune the Jpole antenna in the above article, but my guess(tm) is that VWSR at the band edges is too high. I think you are misinterpreting what this antenna is. It is not a J-pole. It is basically 2 closely coupled dipoles one on 2m and the other on 70cms. The drawing that looks like a j-pole is one half of the antenna ie an element cut to 2m and the other 70cms. Jeff Oops. Y'er right. It's not a Jpole, although it looks like one. More like a "fan dipole": https://www.google.com/search?q=fan+dipole&tbm=isch The 18.63" is 1/4 wave at 2m and 6.25" is 1/4 wave at 440Mhz. Thanks. Incidentally, I forgot to mumble that one doesn't need two dipoles to operate on just the marine band. Also, I can get similar performance out of an 18" bow tie dipole antenna (and balun), or a biconical porcupine: http://802.11junk.com/jeffl/antennas/biconical/index.html -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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