I have a Sony ICF-2010 receiver which has a long wave band, from 150khz. and continuous coverage to 30mhz. this covers all the traditional SW bands and than some.
What I'm getting at is that if you have an amplifier with bandwidth to 100khz, you'll also need an antenna of suitable length. IOW, well over 6000 feet full wave for 150khz. much longer at lower frequencies. Submarines utilizing ULF for communications trail an antenna of some unknown but huge length. The transmitters antenna are huge arrays, visible from space.
I would suggest, however, that the bandwidth limit of 'd' amps is one of the subtle (or NOT?) problems people complain about.
Just by the numbers, I'd suggest a minimum of 2x upper human limit + a guard band....Maybe 44khz with rolloff above that of 3 or 6 db/octave. Now, I'm slippin' here, but where have I seen that number before? hmmmmmm.
Just thinkin' out loud.
What I'm getting at is that if you have an amplifier with bandwidth to 100khz, you'll also need an antenna of suitable length. IOW, well over 6000 feet full wave for 150khz. much longer at lower frequencies. Submarines utilizing ULF for communications trail an antenna of some unknown but huge length. The transmitters antenna are huge arrays, visible from space.
I would suggest, however, that the bandwidth limit of 'd' amps is one of the subtle (or NOT?) problems people complain about.
Just by the numbers, I'd suggest a minimum of 2x upper human limit + a guard band....Maybe 44khz with rolloff above that of 3 or 6 db/octave. Now, I'm slippin' here, but where have I seen that number before? hmmmmmm.
Just thinkin' out loud.