Illustration of the J antenna and four other variations including SlimJIM, Super-J, 5/8ths Super-J and Collinear J.

J antenna and variations thereof

Here we see five variations on the basic J antenna (aka J-pole). Key takeaways include:

  • The basic J and SlimJIM configurations operate identically for all practical purposes.
  • The Super J is an easy way to obtain gain towards the horizon.
  • The 5/8ths Super J represents the most bang for the buck for gain.
  • The Collinear J provides the benefits of the Super Js in a slim package.
  • If on a conductive mast (red) a mast decoupling stub (green) provides essential RF isolation while preserving a direct path to ground.

About John Huggins

John is an electrical engineer working in astronomy and aerospace including antenna/RF design spanning 36 years with experience in antenna design including improvements (US20170201002A1 & USD798847S1) to the J antenna.

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