[NLRS] Mounting 1296 Mhz loop antennas to metalic masts?

[Dr. Gerald N. Johnson]

On Tue, 2006-08-01 at 22:09 -0500, Carl Estey wrote:
> 
> I have contemplated putting up a DSS 1296 MHz 45 element loop yagi and
> mentioned that to Dave, N0KP, during a chat today.  He explained that the
> metallic mast will very seriously degrade performance of the antenna, 

There should be a boom to mast clamp that stays out of the loops. I made
one from a slab of aluminum that used stainless steel hose clamps around
the boom. Then I bent a conduit piece through 90 degrees and hung it
with the loops down. Was only good (27 element) for working Houston and
Sandusky with 3 watts. Going to plastic doesn't help all that much
because you still have to run the coax along the plastic and along the
boom to the feed point.

IMC or rigid conduit bends harder than EMT, but has a far better
galvanize coating so it weathers far longer.

In theory you could split the conduit lengthwise and bend two ears out
to be clamped to the boom with the hose clamps.

I've seen European loop yagi mounts where they ran a second boom
parallel to the yagi boom, about 6" away with smooth bends at the ends
of the second boom. Still the boom to double mast clamps didn't go past
the loop yagi boom.

My boom to mast fitting was made from 1/2" aluminum plate. A triangle
probably 4 or 5" along the boom. I milled a rabbet, probably 1/4" x 1/4"
that the boom sat in. I made some ears for the hose clamps to go around
then I used one or two U bolts to the mast. it could probably be bent up
from 1/16" or 3/32" aluminum just as well.
>  
> 
>  
> 
> When stacking a 1296 MHz loop antenna how do people mount the antenna?  I am
> wondering how a 32" long 1" diameter PVC water pipe might work clamped to
> the metallic mast and extending horizontally to a 90 degree elbow with a
> short vertical piece of 1" PVC pipe to mount the loop antenna.
> 
>  
> 
> Ideas?
> 
>  
> 
> 73
> 
> Carl Estey WA0CQG
> 
> wa0cqg at arrl.net
> 

-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer