[TowerTalk] Downward Mast Extensions

Doug Rehman rehman at surveil.com
Sun Jun 4 18:11:02 EDT 2006

I'm in the conceptual stage of adding a few antennas to my tower. At
present, the 24' of mast above the tower is pretty well filled with antennas
from 7 MHz to 1296 MHz. I plan on adding a few more UHF and microwave

What I am contemplating is attaching a cross arm on the mast just above the
thrust bearing. The cross arm will probably be about 8' long. On each end of
the cross arm, a 10' mast will be attached downward. This will allow me to
rotate the antennas 360 degrees with the other antennas and to retract the
tower. Here's a poor ASCII art idea of what I'm talking about ("U"
represents the tower itself):

   | | |
   | U |

Has anybody ever done this before or seen it done?

Would the wind loading of the antennas on the "down hanging" masts actually
offset against the wind loading of the antennas on the main mast? (This
presumes that the antennas are somewhat balanced on the two down hanging
masts to avoid adding an unbalanced lateral load on the main mast.)

Thoughts, comments, criticisms?


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