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'Resonance' of Buried Radials?

Created by Richard Fry (W9XMT). Authors/source of included graphic are shown therein. on 2020-03-14

... As I tried to point out in my earlier post, resonance of the antenna is affected by the radial lengths and how they interact with the vertical conductor length to create resonance of the antenna system, be it shortened by loading it or not. The interaction is less with on-ground or buried radials, but it still happens. ...
RE (from the clip above): "The interaction is less with on-ground or buried radials, but it still happens."

The phrase "less interaction" there correctly should read "no interaction."

As shown in each case in the graphic below for the same applied r-f power, the accurately measured e-fields radiated by those unloaded vertical antennas of heights ranging from nearly zero to 90+ electrical degrees is a function of the number and length of buried radials used by those verticals.

The curves plotted in Fig. 30 below show no relation of system resonance with the electrical height of the vertical radiator and the buried radials.

If they did show such a relation, and (as claimed by some) — system "resonance" when using buried radials requires specific and inter-dependent conductor lengths totaling a nominal 90° for the vertical radiator plus each radial, then the greatest fields in Fig. 30 below would not be maximum for a vertical of >90° using radials with electrical lengths of ~148° (total length = 238°).

The takeaways here are that:
  • Buried radials perform much differently than elevated radials, and
  • This reality has been known from the quoted BL&E paper published in 1937, and experience with multiple thousands of installed antenna systems used since then by MW AM broadcast stations worldwide.

W0WCA2020-03-14
'Resonance' of Buried Radials?
Affected . . .