[TowerTalk] Christman Phasing help!

[Jim Lux]

Rick has a valuable recommendation

The Christman scheme was, I think, developed to get some gain from a couple 2m or 70cm band whips. 
It is *very* sensitive to the mutual Z and the environment of the two antennas.

If you want to fool with a two element array and directivity, there was a interesting article in one of the antenna compendiums where you basically put a LC network (a manual antenna tuner would work) in series with one of them, and a switch to be able to flip the phase. You adjust the tuner until you get a null on the desired signal, and then reverse the phase. It’s not broadband. But then no simple phasing schemes are.

Now, if you have something like a NanoVNA to measure all the Zs (and with two ports, you can measure Z12 as well as Z11 and Z22), and you want to work the math, you can do the “two coax of different lengths to a T” scheme.
 


On Sat, 6 Sep 2025 14:58:55 -0700, "Richard (Rick) Karlquist" <richard at karlquist.com> wrote:

Read these articles about phased array design on my web site:

http://n6rk.com/driving_the_7_hex.pdf
http://n6rk.com/7_hex_array.pdf
http://n6rk.com/7_hex_eznec.html

I actually built this array and it worked perfectly, without any
problems. This decribes a 7 element array, but can be adapted to
fewer (IE 2) elements.

I do NOT recommend the Christman method.

73
Rick N6RK

On 9/5/2025 4:55 PM, R. David Eagle via TowerTalk wrote:
> Hello all,
> Let me preface this by saying this - I am NOT a phasing expert by any means so I thought I would tackle a new antenna project this summer and maybe learn something....or lose more hair!  So any ways...I decided to put up a pair of phased 1/4 wave verticals and phase them via the Christman method.  Each antenna has 2

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