It was constructed from a single 10-foot length of 3/4 inch copper water pipe and some copper water pipe hanger straps.

What makes this version different from the J-Poles normally seen is the use of copper "sliders" and a SO-239 coax connector for connecting the coax feed line to the quarter wave shorted matching stub.

This makes adjusting the antenna much easier.  Just loosen the screws on the sliders, move them up and down a little and tighten the screws back up.

The completed Copper Cactus J-pole.

Another view showing the full height of the antenna.  Everything below the shorted stub can be removed.  I use the extra length for mounting the antenna.

A view of the SO-239 coax connector and the copper strap sliders.

Another view of the SO-239 connector and the sliders.

A closer view showing the mechanical details of the SO-239 and copper sliders.

Another close up of the feed point.

A view of a completed 2-Meter Copper Cactus J-Pole.  Note the use of a coax choke balun at the antenna feed point.  The J-Pole is a balanced antenna system and a RF choke or split ferrite blocks should be used to prevent currents from flowing on the outside or shield of the coax feed line.