Efficient antennas at that frequency are effectively very long
bits of wire. The ferrite rod is small compared to the wavelength
and very inefficient at generating a far field.

This is the antenna of the DCF77 transmitter (same frequency):
http://de.wikipedia.org/wiki/Bildcf77.jpg

OK Iwo. But why a small receiving ferrite antenna works here? A
non-saturated (=linear, and that means the superposition theorem works)
antenna system is reciprocal as antenna theory predicts. So you should
explain where the difference is!

- Henry