axolotl wrote:

wrote:

I am wanting to get into amateur radio antenna building most plans for
a j pole antenna I have seen use 1/2 inch coper tubing. I was wondering
if I could use stainless steel to make it rust proof. Any ideas where
one could cheaply get small diameter stainless stell tubing?
Any of you out there work with amateure radio antennas?


Many designers stay away from steel and nickel as antenna materials
because they generate passive intermodulation distortion. Probably not a
big concern for ham use. Mcmaster-Carr has stainless thinwall tubing.

Kevin Gallimore



Any bad metal to metal connection can act like a mixer diode and cause
intermodulation if other sources of rf are getting picked up by the
antenna. Some of the earlier ELT beacons were subject to that type of
problem. The adjacent channel signals would go from the antenna into
the freq. multiplier diode in the output and mix with other signals and
re radiate to cause interference on other channels.


John