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FCC NOUO: “Your operation on frequency 1620 kHz was measured at 65,000 microvolts per meter (uV/m) at 100 meters. This exceeds the allowable unlicensed limit of 14.8 uV/m at 30 meters established in 47 C.F.R. S: 15.209(a). Thus, this station is operating in violation of 47 U.S.C. S: 301.”
Ermi Roos: “The field stength measured at the college charged in this particular NOUO corresponds to a radiated RF power from an electrically short antenna of 469 mW. This clearly exceeds Section 15.219 limits, since the input power that is allowed by Section 15.219(a) is only 100 mW, and the antenna length limit of Section 15.219(b) results in an astonisingly low radiated power (even if there is cheating), as I showed in another post in this thread.
If I did this right, the numbers are even worse, Ermi.
Generating a 65 millivolt/meter groundwave field 100 meters from a ground-mounted, base-loaded Part 15 AM setup on 1620 kHz with 20 ohms total of coil and r-f ground loss would take an applied power of almost 80 watts. The r-f voltage at the base of the 3-m whip would be in excess of 6,000 volts !
The above system elevated so that the base of the 3-m whip and transmitter was 6 meters above the earth, and was connected by a 6-meter vertical conductor to the same r-f ground would need about 13 dB less applied power for the same measured field strength. A -13 dB ratio converts to a power multiplier of about 0.05, so the power needed then would be a bit less than 4 watts. The r-f voltage at the base of the whip would be about 330 volts.
Even a perfect 1/4-wave monopole over a perfect ground plane would need about 1/2 watt of applied power to produce this measured field at 100 meters.
It would be interesting to learn what their configuration really was.