What does minimum SWR indicate about the antenna system?

• A. The transmitter is at maximum power
• B. The antenna is resonant at that frequency.
• C. The coax is damaged
• D. The receiver has high gain

Answer: (B)

SWR measures how well the feedline is matched to the antenna. When SWR is at a minimum, the load the line sees is closest to the line’s characteristic impedance and the reactive part of the antenna’s impedance is nearly zero. In practical terms, this means the antenna is resonant at that frequency, presenting a real, matched impedance to the feedline so most of the power is radiated rather than reflected back toward the transmitter. This is why minimum SWR indicates resonance and a good match. It doesn’t imply the transmitter is at maximum power, it doesn’t indicate coax is damaged, and it doesn’t say anything about receiver gain.