• The Maximum Usable Frequency (MUF) for a defined path is the highest frequency at which reflection can take place;  it is independent of transmitter power or antenna gain
  • Frequencies above the MUF will pass through the ionised layer and not be reflected
  • The longest signal path for a particular layer is obtained when the wave leaves the earth and approaches the layer at the most oblique angle possible for reflection
  • Max range for single hop F2 layer propagation is about 4,000 km
  • Max range for single hop E layer propagation is about 2,500 km
  • Greater ranges are possible by multi hop propagation where signal is again reflected off ground or a lower layer