[TowerTalk] Phased vertical feed??

[Tom Osborne]

k6ct wrote:
> 
> I have a 2 element vertical array for 80m. I have received conflicting
> information as to how best to phase the two so I can go in either direction.
> The verticals are spaced 65 ft apart, are elevated and each have elevated
> radials.  Here are the two methods that have been proposed:
> 1. Current fed- using a relay, switching with a 71 degree phase line so that
> the lagging element is the direction of power distribution.
> 2. Parasitic excitation, using 3/8 wave between each vertical and the switch
> box to the shack.
> 
> What are the pros and cons of each and I would like to hear from those of
> you that use these two different feed methods as to efficiency and how well
> the work.
> 73 Tom
> 
> --

Hi Tom.
I'm using a vertical array on 40 using 3 verticals. I used it with 2 
verticals for a long time and it worked very good.  I just had some nulls 
with the array, so I put up the 3rd one to fill in the nulls and it 
worked out very well.
I'm using a 135 degree phasing line with 1/4 wave spacing. If you have 
looked at ON4UN's Low Band DX'ing, there is a wealth of information in 
there on spacing and phasing.  There is a table there that gives the 
folowing info:
1/4 wave spacing with 90 degree phasing: 3 db gain- very good F/B
1/4 wave spacing with 135 degree phasing: 4.9 db gain-little less F/B
1/4 wave spacing with 180 degree phasing: 4.3 db gain-onmi directional
I'm using 135 degree phasing on my array, and it works very well. I can 
null out the foreign broadcast from S-9+20 down to S-8. It is just like 
rotating a beam on 40. With 3 antennas, I can switch to 6 diferent 
directions. I have never used it with a parasitic element so couldn't 
tell you how that would work. I know the phasing configuration works very 
well tho. 73 and GL
Tom W7WHY



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