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Re: Re: Cross boom length?, (Metal Cross Boom)



Hi Joe and other AMSATs,

You are right for linear polarisation. It can also be
seen in the measurement results.

For circular it is some different. Even when you use 2
yagis, each 90 degrees ofset from each other, the RF
radiation is still in all directions.

Even when mounting the x-yagi in a 45 degree angle to
the elevation boom, the horizontal angle will be
reflected by the metal boom, and finally make the
radiation patern elliptical. 

>From the measurements you can see that the yagi 90
degrees to the mast does best. The 45 degrees is half
worse, and the yagi parallel with the boom is worst
off all. For both systems, in matter off angle to
mount the x-yagi on the metal elevation boom, you
would get the same result.

The idea of mounting the x-yagi on the tip of the
metal mast might be a solution, but I never tested
this.

Just my idea,
73 de William
---


Ooo!  One of my favorite topics.

I do not mean to dis-respect William, who is one cool
dude!

When it is actually measured it turns out metal is
just fine if you do it 
right.  Metal is cheaper and stronger as well.  Check
out what happens when 
someone actually measured the results at:

http://www.g6lvb.com/fibermetalboom.htm

Antenna guru Kent Britain, WA5VJB has done the leg
work for us on this.

73,
Joe
kk0sd
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