Explain the difference between VSWR and return loss and how they relate.

• A. VSWR is the ratio of forward to reflected voltage; Return loss is the logarithmic measure of reflected power; Higher return loss means a worse match and higher VSWR.
• B. VSWR and return loss are the same concept expressed in different units.
• C. VSWR is the ratio of forward to reflected voltage; Return loss is the logarithmic measure of reflected power; Higher return loss means a better match and lower VSWR.
• D. Return loss is measured in volts; VSWR is in amperes.

Answer: (C)

VSWR and return loss describe how well power is matched to the antenna, but they express it in different ways. The reflection coefficient Γ quantifies how much of the forward wave is reflected back; its magnitude tells you how severe the mismatch is. VSWR is a direct ratio of voltage magnitudes on the line, often described as the ratio of the highest to the lowest voltage due to standing waves, and it can be computed from Γ as VSWR = (1+|Γ|)/(1-|Γ|). As more power is reflected (larger |Γ|), this ratio grows, indicating a worse match.

Return loss, on the other hand, is a logarithmic measure of the reflected power relative to the forward power. In dB, it is defined as RL = -20 log10(|Γ|) (or equivalently RL = 20 log10((VSWR+1)/(VSWR-1)). A larger return loss means less power is reflected, which corresponds to a better match and a lower VSWR.

Because both rely on the same reflection coefficient, you can move between them using the relationships above. So the best description is that the first part is a simple ratio of forward to reflected voltage, while return loss is a logarithmic, power-based measure of the reflected portion; a higher return loss signals a better match and a lower VSWR.