[TowerTalk] Stacking offset compensation

[HA3LN]

Dear All,

Turning into the final stage lifting the stacks for 10m and 15m before 
ARRL-DX contests
I need a bit of guidance regarding the feed-line setup.

I read in the ARRL Antenna book that if 2x vertically stacked Yagi's
are not exactly in the same vertical plane feed-line length compensation 
is needed to avoid stacking performance degradation.

Both band setups will have similar OWA Yagi types via coax chokes + WX0B 
like stackers.

However, due to the tower geometry it is not possible to position the 
lower antennas to the proper vertical position "below" the upper one.

...for 15m (crank-up tower), is OK to have the lower one "underneath" 
the upper one but with a ~60cm offset to the side direction.
...for 10m (freestanding tower), not only the side ~80cm offset but due 
to the element positions it needs to be pulled a bit back with ~80cm as 
well. So in this case the offset is two dimensional.

- are these less than 1m offsets are serious enough the compensate (with 
aiming for max performance)?
- is it possible/needed to compensate the "side only" offset in 15m case 
as the driven elements will be in vertically same plane?
- these calculation formulas can be used to determine the extra coax 
needed?
(Driver element offset length) / WL x 360 = degrees of delay required
(Driver element offset length) / VF = extra coax length required


Thanks in advance.

73!
Csaba  HA3LN / HG3N