[TowerTalk] 40M interaction

[kk9a@arrl.net]

The subject of placing a 40m beam close to other HF antennas comes up a lot
here on towertalk and usually a spacing of 10' (3m) from the other antennas
is recommended.  Some shortened antenna designs are not resonant on the
other HF bands and may cause less problems, however the manufactures still
recommend the same spacing.  I believe that the biggest interaction problem
is with a 15m antenna.    My question is, is the 40m antenna performance
also degraded by close spacing or is only 15m effected.   I have 15m and 20m
monobanders spaced 7' apart.  Suppose I want to operate 40m single band in a
contest and install a temporary beam in between these.  Could this be made
to work?   Since the booms on the existing HF antennas are much less than
1/2 WL on 40m I  think it would work if mounted at 90 degrees and I don't 
see
why it wouldn't work even if it was set in the same direction as the other 
beams.
Sure the 40m beam will effect the 15m antenna, but I won't be using that 
band.
The Cushcraft 40m beam would be an ideal antenna for me because it's light
weight, small and easy to install and remove.   I haven't tried a model, nor 
do I
really know how to model the shortened elements.  Any thoughts if this is
feasible?

73,
John KK9A  (P40A in WPX CW)