Ionospheric propagation in the L. F. broadcasting band

Continuous field strength recordings made in the UK of l.f. transmissions from Poland and Algeria are described. The results show that sky waves propagate strongly during the day in winter, giving field strengths which are only about 15 dB less than night-time values. In winter, the transition from day to night is very gradual, with the signal strength increasing steadily for several hours. In summer, however, the daytime sky way is very weak and the transition between day and night is more rapid.