Radiation Resistance: Short Verticals

Here's a chart out of Moxon's book, antennas for all locations:

Note:  the chart is for dipoles; for verticals the Rr is half the amount shown.

             So for a vertical 50% of full length:

  • Capacitive end-loaded:    18 Ohms
  • Inductive center loaded:   5 Ohms

As we know, efficiency depends on the ratio of Radiation Resistance to Ground Resistance.  (OK, plus a tiny bit of d.c. resistance – which is negligible)

Thus, it is apparent that capacitive end-load (top-loading) is much more efficient than inductive loading, irrespectable of whether the loading coil is at the base or in the middle of the vertical.