Topband: Boring Report

[Michael Tope]

----- Original Message ----- 
From: "Tree" <tree at kkn.net>

> 
> In the mean time, I believe that it is indeed possible to use a gamma
> matched tower in a phased array.  I know there is a concern that the 
> gamma will affect the phase relationship.  However, thinking about this,
> I believe that the current at the base of the tower has to obey what
> the shield of the coax is trying to do - and all of the gamma "magic"
> doesn't change that.  
> 
> I also know K6SE was able to phase two gamma matched towers with good
> results.  
> 

I see no reason why a pair of gamma matched towers can't be made 
to work in a phased array, Tree, but because of the gamma match I 
don't think that you can rely on current forcing from the Comtek 
unit to produce equal "net current" in the towers. The current 
forcing will produce equal currents in the gamma arms and by 
extension equal currents in the coax shield (assuming that you 
have good radial systems under each tower and adequate feed line 
choking), but the shield current can split into two components - one 
into and out of the radials and the othe into and out of the tower (a 
loop current around the gamma arm circuit if you will). You really 
need to do what Lee suggests and measure the current into the 
gamma arm and also in the tower and then calculate the vector sum 
and make sure this is equal in magnitude and has proper phase
relative to the vector current sum from the other tower.

I wonder if there is anything in the archives as to how K6SE did it?

Mike W4EF.......................