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Re: [TowerTalk] Multiband 1/4 wave sloper

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Multiband 1/4 wave sloper
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Wed, 19 Nov 2025 22:27:56 -0800
List-post: <mailto:towertalk@contesting.com>
Hi Art,

If you're talking about a sloping vertical fed from the base against radials. it's a fairly easy antenna to design in NEC. I had that dipole using components I'd purchased, and the lengths you're thinking about are in the ballpark. I did measure the loading coils at least 15 years ago. I'll see if I can find them.

The way to design it is to build a model with those approximate lengths and start playing with variables until VSWR plots on both bands look good on both bands.

Yes, SWR bandwidth will be very narrow on 160, but coax loss is quite low on that band if you're using RG8.

73, Jim K9YC

On 11/19/2025 9:22 PM, ARTHUR BERNSTEIN via TowerTalk wrote:
With roughly 65 ft for 80 could I resonate it on 160 with wire added after the coil? I 
realize if doable will likely be narrowband which I don’t care as I use 
primarily CW or ft8 on those bands. Inductance of coil and length could be tricky.
Art., N2KA


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