[NLRS] Stacking distances for loopers

[Glen Overby]

When preping for the recent SBMS 2ghz+ contest, I got looking at the stacking
distance specs for Directive's loop yagis.  I've been ignoring these specs and
put the antennas directly on my roof rack (about 4" from the metal roof).
It's easy, but lately I've been wondering how bad that has hurt me?
Directive's page on stacking dis-simmar antennas talks about how much you can
squish antennas together, but not about possibly cutting off the bottom
portion of an antenna's aperature.

Here's the list of stacking distances:

                        Band    #       Boom    Beam    Stacking Distance
                                Ele     Length  Width   E(Horiz)H (Vert)
Directive 3318LYRM      902     18      72"     30      24      21 1/2  
Directive 2324LYRM      1296    24      72"     27      21 3/4  19 1/4  
Directive 1345LY        2304    45      81"     16      15      13      
Directive 945LY         3456    45      60"     16      9.8     9

Directive's advice on stacking antennas says to use half of the stacking
distance for an antenna when calculating stacking distance between
dis-simmilar antennas.

So, my car roof is definately in the aperature of all of these, but how much
does that matter?

Glen, kc0iyt.