Why it matters
When mismatch exists, forward power and net delivered power are not the same; reflected power travels back and line loss dissipates some energy in both directions.
A practical example
A high forward reading beside a high reflected reading does not mean all forward watts reach the antenna.
Use it well
Use directional measurements, account for line loss and reference plane, and avoid subtracting inaccurate small readings as if they were exact.
Keep the measurement reference plane, current program rules, land access, spectrum authorization, and exact packed configuration with the decision. A connector, meter reading, or program name alone does not establish readiness.