To the right is the plan I used for a 23 cm Yagi with VK5DJ's antenna calculator. I used this tool to build several antennas for 33 and 23 cm, and found that they measure very close to the expected performance on an antenna range.

You'll need to know a few things before calculating, such as:

  • frequency (MHz)
  • boom diameter
  • director diameter
  • number of directors
  • directors are in direct contact with the boom or not
  • driven element diameter
  • dipole gap at the feed
  • dipole height (for folded dipoles)
  • balun material

You may have to play with the number of directors parameter to get the gain and beam width you want, or to fill up a given boom length.

Armed with the information this produces from the calculator, one can proceed to the next step.