How does the allowable power density for RF safety change if duty cycle changes from 100 percent to 50 percent?

The concept of duty cycle is important in understanding the allowable power density for RF (radio frequency) safety. When the duty cycle is reduced from 100 percent to 50 percent, it indicates that the RF signal is only transmitting half of the time. This reduction in transmission time effectively lowers the average power delivered to a given area.

The allowable power density, measured in terms of the average power over time, can indeed be increased in relation to the duty cycle. Specifically, when the duty cycle is halved—from 100 percent to 50 percent—the limits for safe exposure can typically be relaxed, allowing for more power density without exceeding safety thresholds. This is because the overall exposure is effectively reduced when the signal is only on part of the time.

Consequently, the allowable power density can be increased by a factor of 2 when adjusting to a lower duty cycle, as the average power density can now be twice as high for the same time-averaged exposure, provided that the exposure over time remains within safe limits. Therefore, the change from 100 percent to 50 percent duty cycle leads to the conclusion that the factor by which the allowable power density can increase is indeed 2.