Plain-language answer: Dielectric breakdown occurs when an insulating material or air can no longer withstand the applied electric field and begins conducting or arcing.
Why it matters in the antenna
Breakdown damages capacitors, cable, connectors, transformers, and insulators; contamination, heat, altitude, moisture, sharp edges, and duty cycle reduce margin.
What to verify
Use rated parts with suitable safety margin, keep surfaces clean and dry, and stop immediately after arcing or insulation damage.
The common mistake
Reusing a component after an arc because it still shows continuity.
Operating boundary
Use the exact documented component, geometry, frequency, power, duty cycle, clearances, and feed/return system. Begin tests at low power and stop for heating, arcing, damaged insulation, or unstable supports.
