If you want to build the most efficient and inexpensive HF vertical antennas, you'll want to select this guide recommended by Peter Waters (G3OJV)
Peter says this guide will give you all the information you need to design, build, test, and use HF vertical antennas.
If you can't see the video, please insert this title URL into your browser search box:
https://www.youtube.com/watch?v=uza3e8E_2uQ.
Here are some comments from Peter (G3OJV):