HAM RF Safety and Station Grounding

Question 1

What is the maximum permissible exposure (MPE) power density limit for the general public in an uncontrolled environment at frequencies between 30 and 300 MHz?

Accepted Answer

0.2 mW/cm²

Answer

The FCC uncontrolled (general public) MPE limit in the 30–300 MHz range is 0.2 mW/cm², which is five times more restrictive than the 1.0 mW/cm² occupational limit.

Question 2

Which factor most significantly reduces RF exposure at a given transmitter power level?

Accepted Answer

Increasing the distance from the antenna

Answer

RF field strength decreases with the square of distance (inverse square law), making increased distance from the antenna the single most effective way to reduce RF exposure.

Question 3

What averaging time is used for RF exposure evaluation in an uncontrolled (general public) environment?

Accepted Answer

30 minutes

Answer

FCC rules require that RF exposure for uncontrolled environments be averaged over any 30-minute period, compared to 6 minutes for controlled environments.

Question 4

What is meant by 'duty cycle' in the context of RF exposure calculations?

Accepted Answer

The ratio of transmit time to total operating time

Answer

Duty cycle is the fraction of total time that the transmitter is actually transmitting, and it is used to calculate the time-averaged power for RF exposure assessment.

Question 5

What is SAR (Specific Absorption Rate) a measure of?

Accepted Answer

The rate at which RF energy is absorbed by body tissue

Answer

SAR measures the rate at which RF electromagnetic energy is absorbed by the human body, expressed in watts per kilogram of tissue.

HAM - Radio Extra Class Test Practice Test

HAM - Radio Extra Class Test Practice Test

HAM RF Safety and Station Grounding