Here in VK anything below 9kHz is unrestricted as long a emissions at those
frequencies do not produce products which extend into the 9kHz and above
bands. I like the idea of this frequency as the frontier for Amateurs is
about 10km (i.e. still near field?). Also it lends itself to my favourite
technique - ultranarrowband and is perfect for my FDK experiments. John
Taylor G0AKN and Graeme Zimmer VK3GJZ have done work in this area.
Have a look at the links on:-
Also Christer SM6PXJ is interested in this area.
73s Steve Olney (VK2ZTO/AXSO - QF56IK : Lat -33 34 07, Long +150 44 40)
Laser Comms DX
Amateur Radio Astronomy