Definition

Reflection occurs when a signal encounters an impedance change (discontinuity) in a transmission line. Part of the signal energy bounces back toward the source rather than continuing to the load. Reflection coefficient ρ = (Z_load - Z₀)/(Z_load + Z₀) determines reflection magnitude: matched impedance (ρ=0) has no reflection; open circuit (ρ=1) reflects fully in phase; short circuit (ρ=-1) reflects fully inverted. Reflections cause ringing, overshoot, and signal integrity problems. Minimizing reflections requires impedance matching and avoiding discontinuities.