I am going to make this one for my next 2 meter antenna....but they can be figured for almost any band if you can get enough copper pipe
Super J-Pole
and here is a regular jpole
J POLE ANTENNA DESIGN CALCULATOR by K4ABT
I built the Super J-Pole several years ago and it worked quite well. Then I replaced it with the 11 element yagi and never looked back.
I used 3/4 inch copper pipe for the bottom section and 1/2 inch for the top section. I used a piece of 1 inch diameter plexiglass rod for the insulator turned down to fit the 3/4 pipe on BOTH ends. I used a 3/4-1/2 inch adapter at the top to mate with the 1/2 inch pipe. I felt that with the larger size it would be stronger and it was going to be at the top of the 40 foot tower. For the phasing stub I used 3/16 copper tubing that I found somewhere around the house left from another project.