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Re: [TowerTalk] Good vacation antenna

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Good vacation antenna
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Thu, 3 Jul 2025 20:53:53 -0700
List-post: <mailto:towertalk@contesting.com>
On 7/3/2025 6:27 PM, john@kk9a.com wrote:
You're not alone Wes.  I also do not understand how having an inductor at
the tuner for an electrically short antenna has a different effect from
putting the inductor at the antenna base.

Dave has provided two excellent responses, which I didn't see before composing mine. And as he correctly observes, we can learn a LOT by choosing to display current distribution in EZNEC on the "show antenna" display, and studying the plots.

When I was getting back on the air in 2003, a colleague in pro audio who also happens to be great RF engineer strongly urged me to use EZNEC, specifically because he'd watched me learn from even more powerful design tools in the design of sound systems. And he was absolutely right! SimSmith is another very powerful design tool from which it's possible to learn a lot.

That "adjustable matching network" called an antenna tuner can take many forms, some of which are more efficient than others. For almost 15 years, I've used stub matching in the shack to broadband my high dipoles for 80 and 40M, all designed with SimSmith using impedance sweeps of the antennas by a high quality and well calibrated VNWA as a starting point.

73, Jim K9YC



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