How does the allowable power density for RF safety change if duty cycle changes from 100 percent to 50 percent?
It increases by a factor of 3
This answer is incorrect because the allowable power density increases by a factor of 2, not 3, when the duty cycle halves.
It decreases by 50 percent
This answer is incorrect because decreasing from 100 percent to 50 percent duty cycle actually allows the permissible power density to increase, not decrease.
It increases by a factor of 2
This answer is correct because when the duty cycle changes from 100 percent to 50 percent, the allowable power density averages over half the time and hence doubles.
There is no adjustment allowed for lower duty cycle
This answer is incorrect because RF safety standards do allow adjustments to allowable power density based on the duty cycle.
Explanation
In the context of RF (Radio Frequency) safety, the term ‘duty cycle’ refers to the fraction of time a transmitter is actively emitting a signal compared to the total time under consideration. This is critical because the exposure limits for RF energy are based on time-averaged exposure, meaning that how often and how long the signal is on versus off will affect the averaged power density over time. When the duty cycle decreases from 100 percent (continuous operation) to 50 percent (only half the time), the allowed average power density actually can increase. This happens because the overall exposure time is reduced, meaning the average power over time is less, even if the peak power remains the same. Therefore, if the duty cycle is halved, the power density limit can increase by a factor of 2 to maintain the same level of exposure over time. This understanding is vital to ensure compliance with RF exposure limits and maintain safe operating conditions, especially for users who may be frequently transmitting at high power levels.
T0C03 2022-2026