Does anyone know if a non-metallic pole approx. 4 m long is available that i can use to mount a vertical 10 m 4 element yagi ? that is not wood, PVC or fiber glass as these are either too heavy or not strong enough. My location is Melbourne in Australia.

  • $\begingroup$ Unless you are willing to go with carbon fiber, I believe the strongest synthetic common non-metal is fiberglass. $\endgroup$ – Chris K8NVH Oct 11 '19 at 0:13
  • 2
    $\begingroup$ I'm guessing you do not actually want non-metallic but non-conductive? Carbon fiber is a good conductor. What is your issue with fiberglass? the mast e.g. of a windsurfing board is plenty strong. $\endgroup$ – loonquawl Oct 11 '19 at 5:56

You could use a metal pole broken up with a few insulators.

One at the boom itself, and one near the ends of the elements, perhaps one more 2.5 m below the antenna, or at the base of the pole.

Don't forget to route the feed cable out around the back of the antenna far from the reflector, or cover it in ferrite beads if it runs down the pole.

  • $\begingroup$ But won't the broken up metal pole segments still get in the way if they are in between the elements ? even if they re less RF "visible" at the frequency being used ... $\endgroup$ – Andrew Oct 15 '19 at 4:33
  • $\begingroup$ Short pieces of metal have very little effect on the antenna. If the section connected to the boom is << 0.25 $\lambda$ or an unconnected section is << 0.5 $\lambda$, it won't couple much to the antenna. $\endgroup$ – tomnexus Oct 15 '19 at 14:43
  • $\begingroup$ so you are saying that i could use a metal pole for a vertical yagi provided that it isn't too long and not connected to the boom ? What is the maximum length it could be without affecting the antenna too much ? $\endgroup$ – Andrew Oct 16 '19 at 8:03
  • $\begingroup$ Yes, if you keep it to less than a quarter wave. But that won't support the antenna, as each element hangs out by a quarter wave. So you will need multiple insulated segments. Connecting fibreglass to metal is quite difficult, bulky and takes up a lot of length, so I still think its easier to make the whole top 3/4 wavelength of the pole out of fibreglass. $\endgroup$ – tomnexus Oct 16 '19 at 9:08

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