Suggest a possible explanation.
As you have learnt in the text, the principle of linear super position of wave displacement is basic to understanding intensity distributions in diffraction and interference patterns. What is the justidication of this principle?

Explanation

a. Interference of the direct signal received by the antema with the (weak) signal reflected by the passing aircraft.
b. Superposition principle follows from the linear character of the solution of (differentia) eaquation governign wave motion. If `y_(1)` and `y_(2)` are solutions of the wave equation so is any linear combination of `y_(1)` and `y_(2)`. When the amplitudes are large (e.g. high intensity laser beams) and non linear effects are important the situation is far more complicated.