Which phenomenon describes radio waves bending around an object?

• A. Refraction
• B. Scattering
• C. Diffraction
• D. Reflection

Answer: (C)

Diffraction is the way waves bend when they encounter edges or obstacles, allowing radio waves to wrap around corners and reach receivers that aren’t in the direct line of sight. This happens because the wavefronts spread out after hitting the edge, sending portions of the wave around the object. The effect is more noticeable when the obstacle size is comparable to the wavelength; longer wavelengths diffract more readily than very short ones. This is different from refraction, which is bending due to a change in medium; scattering, which redirects waves in many directions from rough surfaces or particles; and reflection, which involves bouncing off a surface. In practical UAS communications, diffraction explains how signals can still get through around obstacles, albeit with some loss.