Return loss is a measure in dB of how much power is reflected due to impedance mismatch; higher return loss indicates a better match.

• A. Return loss is the logarithmic measure of reflected power; higher values mean better matching.
• B. Return loss is the ratio of forward to reflected voltage.
• C. Return loss equals SWR.
• D. Return loss increases with frequency regardless of match.

Answer: (A)

Return loss measures how much RF power is reflected back toward the source due to impedance mismatch, and it is expressed in decibels to show the ratio of forward power to reflected power. The key idea is that a good match sends almost all the power to the load, so very little is reflected, which yields a high return loss value. Mathematically, return loss in dB is RL = 10 log10(P_forward / P_reflected), which is also described as RL = -20 log10(|Γ|), where Γ is the reflection coefficient. Since |Γ| is less than or equal to 1, a smaller reflected portion gives a larger RL, indicating a better match. If the load is perfectly matched (Γ = 0), the return loss tends toward infinity in theory, representing no reflected power; as the reflection grows, the return loss value decreases, signaling a poorer match.

The other statements don’t fit because return loss is about power, not a simple voltage ratio; it is related to SWR but not equal to it, and it depends on the match rather than increasing with frequency regardless of how well the system is matched.