PROBLEM TO BE SOLVED: To substantially reduce the effects of fading and noise by supplying rotation, corresponding to signals to the polarization plane of radio waves to be transmitted.
SOLUTION: A signal controller (e) controls transmission radio waves by input signals. When the output voltage of the signal controller (e) is 0 volt, the output frequency of a low-frequency transmitter (c) is inputted through a balanced modulator (b) and a phase shifter (d) to the balanced modulator b' and ultimately sent out from dipole antennas X and Y as balanced modulation waves. At the time, the polarization lane of the radio waves to be transmitted is rotated at a speed equal to a frequency outputted to the low-frequency transmitter (c). Also, when a fixed DC voltage is outputted to the output of the signal controller (e), the balanced modulators b and b' lose the function of balanced modulation and output the carrier waves of a transmitter (a) as they are. The rotation of the polarization plane is stopped. In the meantime, in order to receive the radio waves transmitted in such a manner, a normal antenna and a normal single side wave band receiver (SSB) are used.