Ham Radio General Class Practice Test

What standing wave ratio will result from the connection of a 50-ohm feed line to a non-reactive load having a 50-ohm impedance?

1. 2:1

2. 1:1

3. 50:50

4. 0:0

The correct answer is: 1:1

The standing wave ratio (SWR) is a measure of how effectively radio frequency power is transmitted through a transmission line. It is defined as the ratio of the maximum power to the minimum power along the line, which is influenced by the impedance of the load connected to it. In this scenario, the feed line has a characteristic impedance of 50 ohms, and it is connected to a non-reactive load that also has an impedance of 50 ohms. When the impedances of the feed line and the load match perfectly, there are no reflections of the radio frequency signal back toward the source. This results in optimal power transfer and a standing wave ratio of 1:1. A SWR of 1:1 indicates that the entire power is being absorbed by the load with minimal loss due to reflections, which is the ideal condition for efficient operation in radio communications. This situation is desirable because it means that there are no standing waves being formed along the feed line. Other options such as 2:1 indicate some level of mismatch, while 50:50 and 0:0 do not represent valid SWR measurements. Thus, connecting a 50-ohm feed line to a 50-ohm load results in a SWR