You can use ferrit antenna rods. That works for receivers very fine in VLF
band and for transmitters too - as long as the ferrit won't go into
saturation.
That is a magnetic antenna and it is much shorter than the equivalent
mentioned.

- Henry


"Paul Keinanen" schrieb im Newsbeitrag
news
On Fri, 29 Sep 2006 17:13:28 -0700, "Joel Kolstad"
wrote:

No. The problem is that wavelength of a, say, 10kHz signal is 3km in
free
space.

This must be a typo, since the free space wavelength at 10 kHz is 30
km.

Paul OH3LWR