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Re: [Antennaware] Phased Butternuts?

To: "Jim Miller" <JimMiller@STL-OnLine.Net>
Subject: Re: [Antennaware] Phased Butternuts?
From: "K9AY" <>
Date: Mon, 12 Feb 2007 16:04:58 -0600
List-post: <>

Some years ago, I worked with another ham to feed his two HF2Vs in-phase 
(broadside) -- the biggest problem was getting the two antennas to have 
identical feedpoint impedance. It took plenty of tweaking; each antenna 
seemed to have a different shift between independent and mutual coupled 

Once we got the two matched, the pair worked well on 40M (primary band of 

Around that same time I had two 40M ground planes -- full-size verticals fed 
30 feet up, with (3) radials that doubled as guys. Spacing was about 160 
degrees, and they were very "tame" when it came to phasing.

73, Gary

> At 06:25 AM 2007-02-12, Jim Miller KG0KP wrote:
>>I have two Butternut vertical antennas (HF6V and HF9V) now that I
>>have rebuilt the parts one I acquired.  I would like to consider
>>phasing them and expect it would work for "any" particular band but
>>wonder what the effect would be on the other bands.  Would other
>>bands be degraded or could both antennas be driven with the proper
>>phasing (by band) and be effective?  What physical separation
>>distance would be recommended?  Same physical distance must serve all 
>>I expect this could be modeled separately as monoband verticals but
>>I am new at modeling and do not know how to model phasing.
> I'm not too familiar with the specifics of these antennas, but as
> long as they are fairly close to the same size (in wavelengths) and
> similar feedpoint impedance on each band, you shouldn't have too much
> trouble phasing them.
> You can obtain either of two bidirectional patterns (90 degrees
> apart) on the band where the antennas are 1/2 wl apart.  You can get
> cardioid (unidirectional, endfire)) patterns on the band where they
> are 1/4 wl apart.  It is possible to get endfire patterns on a band
> where they are 1/8 wl apart, but the feed impedances can get really
> low due to the mutual coupling and make it hard to get good
> efficiency (unless you like laying lots of radials).
> On higher bands where the spacing is 3/4 wl or more, there will be
> several lobes, regardless of the phasing.  However, you can steer the
> lobes (and nulls) by adjusting the phasing.
> Modeling phasing is easy.  Just put a current "source" at the base of
> each antenna and adjust the phasing to get the pattern you
> like.  (EZNEC comes with a sample 2-element phased array with 1/4 wl
> spacing and 90 degree phasing in a file called CARDIOID.EZ , plus a
> similar one with a transmission line feed network called CARDTL.EZ).
> Getting equal currents and the desired phase in the real world is a
> heck of lot harder than modeling them!
> 73, Terry N6RY

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