What effect does lowering a signal’s transmitted elevation angle have on ionospheric HF skip propagation?
Faraday rotation becomes stronger
The MUF decreases
The distance covered by each hop increases✓Correct answer
The critical frequency increases
Explanation
A ray launched at a lower elevation angle strikes the refracting layer at a larger angle of incidence, so it travels much farther downrange before it is bent back to Earth and each hop covers more ground. Lowering the angle in fact raises the path MUF rather than lowering it, because the maximum usable frequency of an oblique path grows with the secant of the angle of incidence, while the critical frequency is by definition a vertical-incidence measurement that no change of takeoff angle can alter.