Total posts : 45366
We agree on the difference in gain and fields for a short monopole compared to a 1/4-wave monopole, for the same system losses.
BTW, there is a typo in your statement for the 1/4-wave field at 1 km for 1 kW — the unit of measure should mV/m instead of mW/m.
The FCC agrees with Rich’s statement that an elevated antenna does not necessarily have more efficiency than one that is at ground level.
But the efficiency of an elevated Part 15 AM antenna system IS greater than one at ground level. My post attempted to show what was responsible for that.
To clarify, the increase in Part 15 AM antenna system efficiency and field strength when elevated is the result of radiation by conductors OTHER than the 3-m monopole, and not the result of greater radiation or better path clearances from the elevated 3-m monopole, itself.