The J-Pole (affectionately known as the "North Pole") - a few bits of metal, a few hours and you'll have the simplest best omnidirectional FM antenna in the world


What you need:

  • aluminium tubing
  • base plate
  • tv antenna clamp
  • antenna mount (eg. a bargeboard mount) with screws
  • 75 Ohm shielded coaxial cable
  • 6 bolts (very small, small and larger)
  • a small piece of sheet copper
  • a long piece of cheap wire
  • a long metal stake
  • a metal hose clip

What it looks like:

Some tips:

  • when drilling into aluminium tubing, get a wooden dowel that fits snugly within the aluminium tube (to stop the tube crimping)
  • mount the antenna as high as possible
  • the small piece of copper sheet is cut into 2 straps that wrap tightly around the tubes (as indicated). They should be able to slide up and down to tune the antenna. Each strap should have 2 holes cut in it and a very small bolt inserted to tighten the straps against the aluminium tubes:

  • attach the inside wire of the coax cable to one of the copper straps and the outer braid to the other copper strap
  • tune the antenna in the morning (FM signals are normally steadiest in the morning) by finding the worst station that you can and making it as clear as possible
  • to ensure that if hit by lightning the strike causes as little damage as possible (still probably substantial): hit the metal stake a long way into the ground, attach the long piece of cheap wire to the stake and use the metal hose clip to keep it in place and make a good connection. The other end of the wire needs to be connected securely to the antenna making contact with the base plate.
  • spray around the copper straps and base plate with a clear lacquer to preserve them

If you have any queries about the J-Pole, please drop me an email:
.

I'd also really appreciate hearing any comments if you construct the J-pole!

You might also like to check out my radio show, Nothing Happening, and The Marvellous World of King Craig.