A power line of 108 km length in the Kola Peninsula, Russia, was fed by a tunable AC current in the upper ULF and lower ELF frequency band. Its magnetic signature was received by the Finnish chain of pulsation magnetometers at distances from 200 to 1000 km from the source. Amplitudes and polarization properties were analyzed as a function of frequency, distance, line-of-sight angle, and local time. Some evidence was obtained that, beside the geological structure underneath the radiator, also different ionospheric conditions affect the received signal properties in a systematic way. The efficiency of the power line as an ULF-wave radiator proved to exceed largely those typically obtained in similar experiments based on modulation of ionospheric currents by powerful HF heating.