Plain-language answer: High SWR means the impedance presented at the measurement point differs substantially from the line’s reference impedance; it identifies a mismatch, not its cause.
Why it matters in the complete station
Possible causes include the wrong configuration or band, incorrect dimensions, missing return path, nearby conductors, damaged coax, bad connectors, water, or an unsuitable measurement plane.
What to do in the field
Stop transmitting at high power. Verify the guide and assembly, inspect connections, measure R and X at the feedpoint if possible, and substitute known-good sections one at a time.
The common mistake
Randomly trimming the radiator before ruling out feed-line and assembly faults.
Safety boundary
Stop work around power lines, lightning, unstable supports, unsafe wind or ice, damaged components, or uncontrolled public access. Current product guides, component ratings, site rules, electrical code, license conditions, and RF-exposure requirements control the final installation.
