Which VSWR value is best for transferring RF energy between connections?

• A. 2.0:1
• B. 1.5:1
• C. 3.0:1
• D. 1.2:1

Answer: (D)

Efficient RF energy transfer depends on how well the impedance of the transmitter, line, and load are matched. When they’re matched, almost none of the energy is reflected back, so the forward power delivered to the load is maximized. VSWR is a quick way to gauge that match: a value of 1.0:1 means a perfect match and no reflected power; the larger the VSWR, the more energy bounces back and the less arrives at the load.

Among the options, 1.2:1 is the closest to a perfect match, so it minimizes reflections and maximizes transfer. You can think of the reflection as a small fraction of power bouncing back; for 1.2:1 the reflected portion is very small, whereas larger VSWR values show noticeably more reflection (1.5:1 has more, 2.0:1 even more, and 3.0:1 quite a lot). This makes 1.2:1 the best choice for transferring RF energy efficiently.