K7ITM wrote:
On Feb 5, 11:15 am, Dave99 wrote:
Hello,

Does anyone know if there's a way to determine the velocity factor of
various metal tube types, diameters and gauges?

Also, on the same subject... Is there any reason why a collinear
couldn't be constructed from metal tubing pieces, in the same basic
method of a coax collinear?

Thanks for any help,

Dave

I'm not sure just what you mean by "the velocity factor" of metal
tubes. Generally it's not the metal but the dielectric that
determines velocity factor.

But for sure you can construct a collinear from metal tubing pieces.
After all, coax is just a metal tube (which may be braided, foil or
solid) surrounding a center conductor.

I suspect he means what length would be needed for a resonant quarter or
half wavelength. That's a function only of the diameter. You can find
graphs of a "shortening factor" for dipoles or some such in numerous
places such as the _ARRL Antenna Book_. Or you can get that information
very quickly and easily with the free EZNEC demo program from
http://eznec.com or with any other antenna modeling program.

Roy Lewallen, W7EL