This has been gone over a zillion times. Short answer; Mount them in an "X" configuration and don't worry about it. http://www.g6lvb.com/fibermetalboom.htm
--- On Sat, 7/25/09, Kevin Groth hislens@gmail.com wrote:
From: Kevin Groth hislens@gmail.com Subject: [amsat-bb] Cross boom question To: amsat-bb@amsat.org Date: Saturday, July 25, 2009, 1:47 PM
I have just finished building a set of 2m and 440mhz circular polarized beams to work the birds. (tired of standing in the heat and cold outside!) I tried to save a little bit of money by building a wood dowel inserted into a sched 40 uv resistant pipe. I hung the beams on either side of the cross boom and it sags way too much and is ugly. I thought about using some eyebolts and some nylon cording for support to the vertical mast, but I'm trying to keep everything as clean as possible for the neighbors. I would really rather not have to purchase a fiberglass satellite boom commercially, but if I have to, I will.
I have a bunch of 1.75" aluminum pipe that would be more than able to support most anything I plan to add to the antenna collection in the future (1.2 and 2.4 ghz). My question is how much of a difference would it make if I mounted the 2m and 440 beams in an X position to the aluminum beam? I have read some short answers that it would minimize the swr issue, but haven't really found an answer that I am comfortable with. Also, how would that effect a later addition like a 1.2 or 2.4 ghz antenna.? My current antennas are a KLM 2m-14c and a 435-40cx, both circular polarized and switchable RH and LH polarization. Does anyone have any experience with a metal crossboom?
Thanks!
Kevin
N9EME
Fort Worth, TX
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