Original article from: Wayne Sarosi 
 Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo.
  THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL
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SUBJECT:  Attic VHF/UHF Rotatables
 In many instances,a ham can mount a VHF or UHF beam in the attic,on a rotor.
 They can achieve good results depending on their location and height off the
ground. Antenna size limitations are soley dependent on the available room in
the attic that allows rotation of the beam without hindering it's rotation.
 To check the attic for the maximum size antenna,the ham must first enter the
attic and measure the distances in the area planned for the set-up.
 Trusses,electrical wiring,air conditioning / heating ducts,and the items 
hat
are stored up there,can all play a factor in the actual antenna size.
 Finding your antenna with a pair of long johns dragging off the front end is
not a pretty sight.
 After measuring the area in the attic,the antenna size and height off the
attic cross members can be accomplished.
 Remember to allow for a base to accommodate the rotor,this too must be
calculated into the system.
 Building a sleek system,to rotate two or three small beams,can be 
ashed,when
the system will not turn because of an oversight in the measured values of 
he
attic area in question.
 Turning radius is the important factor. Each antenna forms a rectangle ABCD
where the maximum distance is AD or BC.
              A------------------------------------B
               |                                  |
               |                                  |
           ----|----------------------------------|---- BOOM
               |                                  |
               |                                  |
              C------------------------------------D
 For horizontal antennas,the turning radius is from the mounting point to the
tip (either side) of the longest element. Multiple this figure by two for the
turning diameter of the antenna.
 For vertical antennas,the truss angle places the biggest problem as the
height from the boom to the tip of the refector (B or A). In essence,this 
ill
shorten your boom length or require a lower rotor mounting.
 These tips will help the Amateur avoid any problem before getting the system
in the attic.
-WS
--- GoldED 2.42.G1219
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