This will be a very easy explantion of how Radiation angle work and how this will effect your HF radiocommunication below 30 mhz.
Every antenna have a radiation-pattern. This pattern describe wich angle the signal will leave/enter your antenna. So before you make/buy an antenna, you need to know the purpose of your radiocommunication. If you want to make long distance contacts (DX) over etc 3000 miles, you will need an antenna with low radiation angle (Take off angle = TOA). If your purpose is domestic contacts in your local area you want an antenna with high angle of radiation. That way the signal will go straight up to the atmosphere and right down.
The picture below will illustrate this. A and B are good for long distance contacts. That could be a vertical antenna with low radiation angle or an dipole that’s elevated atleast 1 wavelength above ground. The C example may be a low elevated dipole (< 1/2 WL over ground) for local contacts. For you can see the signal will go straight up, and straight down.
Horisontal dipoles, long wire’s , yagi’s and other horisontal antennas will work so good you want it to work by decide the hight of the antenna. A thumb rule are if you want a long skip distance, you have to put the antenna atleast 1 wavelength above ground. (20 meters on 14 mhz).
If you want to rag-chew on the 80m band with your local HAM’s you hang the dipole on a low height. (10-60 feet f.e)
Under you can see radiation pattern of different antennas on different hights.
