Why is duty cycle one of the factors used to determine safe RF radiation exposure levels?

Duty cycle is a critical factor in determining safe RF radiation exposure levels because it relates to the average amount of time a transmitter is actively radiating energy compared to the total time period being considered. When calculating exposure, it's important to look at how frequently and for how long a transmitter is on. A higher duty cycle indicates that the transmitter is active more often, which means that the average exposure for individuals nearby will be greater over time.

When assessing RF radiation, the focus is on the cumulative exposure a person receives, which includes not just the strength of the signal but also the duration of that exposure. For instance, if a signal is transmitted continuously, the risk of health effects from RF exposure increases significantly compared to a signal that is transmitted intermittently, even at the same peak power level.

This variable becomes crucial when developing safety guidelines and regulations for RF exposure, as it ensures protection levels are adequate for those who might be exposed to signals in a range of scenarios, including near the transmitter and during varying operational states.