[TowerTalk] Does Mast Destroy V-Pol UHF Beam Pattern??

[i4jmy@iol.it]

The mast doesn't necessarily destroy the pattern althought such type of 
risk effectively exist and depends by multiple variables. 
Same story apply to a coaxial cable that runs parallel to elements. 
Therefore the fiberglass mast won't insure at all or always prevent 
interactions and antenna pattern distortions.
The best way to overcome the problem is to mount the antenna on a sort 
of horizontal mast (like when horizontally stacking two antennas) that 
results normal to elements.
In this way, shifting the antenna half wavelenght (or more) from the 
mast and making the coaxial line to follow the boom, the horizontal 
mast and then the vertical mast, one can be quite sure to really avoid 
the electrical problems.
Concering the mechanical point, in the case the antenna weight is 
consistent, some counterweight opposed to the antenna (why not a second 
antenna...) could be required to avoid the vertical mast is subdue to a 
lateral force.

73,
Mauri I4JMY



> ---------- Initial message -----------
> 
> From    : owner-towertalk@contesting.com
> To      : towertalk@contesting.com
> Cc      : 
> Date    : Thu, 27 Jul 2000 18:36:46 -0500
> Subject : [TowerTalk] Does Mast Destroy V-Pol UHF Beam Pattern??
> 
> 
> I have a 25 element 432 MHz beam (K1FO design) that I want to mount
> vertically polarized for Amateur Television (ATV).
> 
> Will mounting it up against a vertical steel mast destroy the pattern?
> 
> If so, I thought I could use a vertical fiberglass mast except the 
coax
> cable that connects to the beam would probably cut into the pattern 
too.
> 
> 73,
> Dave Rich
> kg0us@swbell.net
> 




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