What is the name of the distance from the antenna to the point where the power density equals the MPE?

• A. The Safe Distance
• B. The Estimated Hazard Distance (DMPE)
• C. The Operational Radius
• D. The Exposure Boundary

Answer: (B)

The distance at which the RF power density reaches the maximum permissible exposure (MPE) is the boundary used in safety planning to separate potentially unsafe exposure from safe exposure. This boundary is called the Estimated Hazard Distance, abbreviated DMPE. It marks the point where the actual power density equals the MPE limit; inside that distance, exposure would exceed MPE (and be hazardous under the standard), while outside it, exposure is at or below the limit.

In practice, this distance depends on the antenna’s transmitted power and gain and the frequency-specific MPE limit, often derived from the inverse-square relationship in the far field. The term DMPE emphasizes that it’s an estimated boundary to help determine safe operational distances. Other options use more generic terms that don’t specifically denote the official exposure boundary defined by MPE.