I have a 3 element SteppIr on order. All this ocean in my front yard
eats yagis, and having a fiberglass tube with the electrical element
inside should be better than exposed aluminum and SS hardware. The
stepper motors have proven their durability in the computer industry,
but time will tell.
As for varying the boom length, a screw mechanism should work by either
contracting/expanding the boom, or varying the element placement on a
track. I am willing to accept fixed element spacing in the interest of
structural integrity.
Most of our multi-band antennas are a compromise other than full sized,
single band yagis.
Jon Hamlet, W4ZW
Casey Key Island, FL
"A little bit of Paradise in the Gulf of Mexico"
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