Can S-Meter readings tell the radiated power?
Yes, we can make a rough calculation of the radiated power of a station heard. This works best with signal strengths above S9 and a calibrated attenuator, assuming that the S-meter has been set to S9 at -93 dBm. The precondition of course is a propagation peak. For that, let us assume that the ionospheric diffraction loss is 6dB per hop. Let us talk about sporadic-E contacts. For a distance of 1500 km the formula gives a free space loss of 130 dB. With one ionospheric hop the attenuation for isotropic antennas would be 136 dB. With a 10dBi antenna on the receiving side the adjusted signal loss is 126 dB. A practical measurement. The strongest TV carrier signal ever received at DL7AV was Spanish TV on 48.250 at -43 dBm. A vertical HB9CV antenna was used which might have a 6 dBi gain, resulting in a net signal loss of 130 dB. The addition of both values results in a radiated power of +87 dBm, equal to 500 kW. This number is 3 dB above the radiated power of that station which I found late
