Why is impedance matching important in RF systems?

Impedance matching ensures maximum power transfer and minimizes signal reflections between source, transmission line, and load. When impedances are mismatched, part of the signal reflects back (quantified by reflection coefficient Γ = (ZL-Z0)/(ZL+Z0)), causing standing waves and power loss. VSWR (Voltage Standing Wave Ratio) measures mismatch severity; ideal is 1:1, acceptable is typically <2:1. Matching techniques include: L-networks (series-shunt components), stub matching, quarter-wave transformers, and Smith chart-based design. Standard RF impedance is 50Ω (compromise between power handling and loss for coax) or 75Ω (minimum loss for video).