ARRL Technician Practice Exam 2026 – Complete Prep Guide

Standing wave ratio (SWR) is fundamentally a measure of how well a load is matched to a transmission line. It quantifies the efficiency of power transfer between the transmission line and the load, such as an antenna. When the load is perfectly matched to the transmission line, the SWR is 1:1, meaning all the power is transmitted to the load without reflection. If the load is not well matched, some of the power reflects back towards the source, leading to a higher SWR. A high SWR indicates inefficiencies, which can result in lost power and potential damage to the transmitter.

Understanding SWR is crucial for any radio operator, as a high SWR can affect the performance of the antenna system and reduce the effectiveness of your radio transmission. Recognizing that SWR is specifically about the relationship between the transmission line and the load helps to clarify why this choice is the most accurate description of the concept. This choice does not delve into power loss in the cable or the physical characteristics of antenna height or modulation techniques, which are unrelated to the definition of SWR.