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Re: [TowerTalk] 40 meter dipole

To: towertalk@contesting.com
Subject: Re: [TowerTalk] 40 meter dipole
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Mon, 2 Oct 2023 11:02:07 -0700
List-post: <mailto:towertalk@contesting.com>
On 10/2/2023 10:19 AM, Steve Babcock wrote:
However Yagi performance IS a function of the narrow bandwidth of a shortened 
PARASITIC element. (not the driver)

No debate on that, but I'm specifically talking about dipoles.

Higher frequency bands in fan dipoles also exhibit reduced SWR bandwidth, as low frequency bands in multi-band loaded dipoles (like the common 2-band dipole with a loading coil near what would be the resonant point of the second harmonic of the band for which the loading coils are used. For example, 80/40 and 40/20. I was first introduced to the idea from commercial versions of those designs for 80/40 and 160/80, and did my own designs of a 40/20 versions using both wire and aluminum elements for CQP expeditions. Again, efficiency and pattern are not significantly affected by loading, acting like ordinary half-wave dipoles on both bands.

73, Jim K9YC


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