Gene Fuller wrote:
"The specific number, 22 dB comes with some specific conditions."

Yes, but when you are calculating the decline in field due to distance
from the source, 22 dB is convenient as the reduction within the first
wavelength. Every time the distance doubles after the first wavelength,
the volts per meter are halved. The power per square meter is thus
quartered (decreases by 6 dB).

Best regards, Richard Harrison, KB5WZI