Subelement J: Antennas— Topic 64: Voltage, Current and Power Relationships
Question 3-64J3
Element 3 (GROL)Which of the following represents the best standing wave ratio (SWR)?
Explanation
Standing Wave Ratio (SWR) measures the impedance match between your transmitter and the antenna system. A perfect SWR of 1:1 indicates that the antenna system's impedance precisely matches the feedline and transmitter's output impedance (typically 50 ohms).
In a 1:1 SWR scenario, all the radio frequency (RF) power sent from the transmitter is absorbed and radiated by the antenna. There is no power reflected back towards the transmitter, ensuring maximum efficiency and minimal stress on the radio's final amplifier stage.
Conversely, higher SWR values like 1:1.5, 1:3, or 1:4 signify a greater impedance mismatch. This mismatch causes a portion of the RF power to be reflected back down the feedline towards the transmitter. Reflected power reduces the effective power radiated by the antenna and can cause the transmitter to reduce its output power or potentially lead to damage over time. Therefore, 1:1 represents the ideal, most efficient SWR.
Related Questions
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