Plain-language answer: Loss resistance is the resistive part of antenna input that converts accepted RF power into heat rather than radiation.
Why it matters in the antenna
Conductor, coil, transformer, connection, ground, dielectric, and nearby-material losses can all contribute while still producing a low SWR.
What to verify
Account for feed and component loss, watch heating, and use controlled field comparisons when efficiency matters.
The common mistake
Assuming every resistive ohm at the feedpoint is radiation resistance.
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.
