[CQ-Contest] 4O3A Station rebuild

[David Gilbert]

Ranko,

I'm not sure I understand the appeal of the 4x 2L40 in H-frame 
configuration.

1.  Whatever gain you get from the horizontal phasing will come with the 
penalty of narrower beamwidth, and I'm not sure that's desirable for 
covering USA/VE/Caribbean.

2.  The theoretical maximum you can gain from the horizontal spacing is 
3 db and in practice would be less.  You could get most of that same 
gain with better pattern by simply using a single stack of two 4-element 
antennas on one tower.

3.  While beaming US/VE on 40m you run the risk of wasting whatever else 
is on the two towers if propagation happens to be better to some other 
location on those other bands.

4.  No matter how you try to optimize the spacing between the two 
towers, you will only get your best gain and pattern broadside to the 
two towers.  If you try to swing both sides of the H-frame somewhere 
else you dramatically disturb the phasing that gave you your optimized 
gain.  A stack on a single tower holds its gain and pattern no matter 
where you point it.

I'm probably missing something there, but it just seem like 3 rotary 
towers could be put to better use.

In any case, 73 and best of luck on your rebuild!

Dave  AB7E



On 4/20/2018 7:10 AM, Ranko Boca wrote:
> Hi Frank,
>
> nice to hear from you.
>
> I will have 3 rotary towers. On 40M I will have 2/2, plus four tribanders.
> Towers are in triangle, and  will be able to turn two of them toward USA or
> JA. Want to have optimized 4x 2L40 in H frame configuration.
> Exactly what you are saying, I have to look for 20M antennas, to fit this
> optimized 40M distance of towers. Based on its boom length, I will look for
> adequate tribanders, or will decide to make it by my own.
>
> I hope it is more clear now?
>
> 73
> Ranko
>