Definition of VSWR Stability of a Load

VSWR stability is defined as the change in Return Loss from no power applied to full power applied, assuming the ambient temperature does not change.

For example with no power applied the 8931-115 load VSWR is 1.20:1 at 13.56 MHz, or 40.086 dB Return Loss.

Applying 10kW (full rated power of the 8931-115), the Return Loss will change by no more than +/-0.1 dB at 13.56 MHz +/- 10 kHz.  So the final Return Loss will be 39.986 dB to 40.186 dB or 1.198 to 1.202 VSWR.