Hi Paul -

Some field strength measurements made in England at 73 kHz during the
summer, using a calibrated meter indicated 25 uV/m in 200 Hz
bandwidth, which would produce about 120 dB more power from a full
sized (2 km) dipole than a single matched resistor at the receiver
input.

My receiver bandwidth is about 10Hz because of the 77.5KHz quartz crystal
filter. So the sensitivity is better. Is 10*lg(200/10) here correct?


Thus, even if the actual antenna efficiency was -100 dB and the LNA
noise figure as bad as 10 dB, the band noise would still be stronger
than the amplifier noise.

While an antenna with -100 dB gain would be usable for receiving, such
antenna would be useless for transmitting.

It is interesting to learn, that antennas can be noise limited. So
reciprocal theorem is not all to know.

Thanks -
Henry