[Elecraft] Vertical phasing using Christman KB8I method

[Allen Ward]

Hi Brian,
Yes I have looked at the Lewallen method which for two 1/4 wave verticals
consists of an inductor and capacitor which can be tuned in place.  The
Christman system consists of carefully selecting cable lengths to both match
to 50 ohms and provide the desired phase shift (135 degrees in my case) and
would indeed vary as the frequency changes.  I suppose that if one intended
to operate over a very narrow frequency like +/- 10 kHz it wouldn't be a
problem.  I would like to get info from someone who has actually used the
system (I often model things and wonder how they would really work!  Hi
hi.).
Thanks and 73
Allen KA5n


> I have done some modeling of this approach using a design spreadsheet and
> EZNEC. Like any phasing system, its effectiveness depends to a great
extent
> on how the properties of the loads vary over frequency. The approach works
> perfectly at exactly one frequency, but the performance -- in terms of
> maintaining current and phase balance to give the desired radiation
pattern
> -- changes as you move away from the design frequency.
>
> I was going to say that the "Lewallen method" -- using only 1/4-wave
> sections plus a small number of matching components -- would be less
> sensitive to frequency variations, but it will also depend strongly on
> exactly how your load impedances vary.
>
> Brian K1LI
>
> -----Original Message-----
>
> Has anyone used the antenna array phasing method described by Al Christman
> KB8I in the May 1985 Ham Radio Mag and later used in the book "Low Band
> DX-ing."
>
>