What does SAR measure?
The correct answer is C: The rate at which RF energy is absorbed by the body. SAR (Specific Absorption Rate) measures the rate at which RF energy is absorbed by the body. SAR is expressed in watts per kilogram (W/kg) and is a key parameter for RF exposure evaluation.
SAR quantifies how much RF power is absorbed per unit of body mass. It's the standard measure used to evaluate RF exposure and set MPE limits. Higher SAR means more RF energy is being absorbed, which increases the risk of heating and potential health effects. SAR depends on frequency, power density, and how the body interacts with the RF field. MPE limits are based on SAR values that are considered safe. SAR is measured in controlled laboratory conditions and is used to establish the exposure limits that amateurs must comply with.
Exam Tip
SAR measures = RF energy absorption rate. Remember: SAR (Specific Absorption Rate) measures the rate at which RF energy is absorbed by the body, expressed in watts per kilogram (W/kg).
Memory Aid
"**S**AR = **R**ate **R**F **E**nergy **A**bsorbed (think 'SAR = RREA')"
Real-World Application
You're evaluating RF exposure. SAR tells you how much RF power your body absorbs per kilogram. If SAR is 0.08 W/kg (the limit for general public), that means your body is absorbing 0.08 watts per kilogram of body weight. Higher SAR means more absorption and higher risk. MPE limits are based on safe SAR values.
FCC Part 97.13Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. SAR doesn't measure signal attenuation ratio. SAR is about energy absorption by the body, not signal attenuation.
Option B: Incorrect. SAR doesn't measure signal amplification rating. SAR measures how much RF energy the body absorbs, not signal amplification.
Option D: Incorrect. SAR doesn't measure RF energy reflection from terrain. SAR is about energy absorption by the body, not terrain reflection.
题目解析
The correct answer is C: The rate at which RF energy is absorbed by the body. SAR (Specific Absorption Rate) measures the rate at which RF energy is absorbed by the body. SAR is expressed in watts per kilogram (W/kg) and is a key parameter for RF exposure evaluation. SAR quantifies how much RF power is absorbed per unit of body mass. It's the standard measure used to evaluate RF exposure and set MPE limits. Higher SAR means more RF energy is being absorbed, which increases the risk of heating and potential health effects. SAR depends on frequency, power density, and how the body interacts with the RF field. MPE limits are based on SAR values that are considered safe. SAR is measured in controlled laboratory conditions and is used to establish the exposure limits that amateurs must comply with.
考试技巧
SAR measures = RF energy absorption rate. Remember: SAR (Specific Absorption Rate) measures the rate at which RF energy is absorbed by the body, expressed in watts per kilogram (W/kg).
记忆口诀
**S**AR = **R**ate **R**F **E**nergy **A**bsorbed (think 'SAR = RREA')
实际应用示例
You're evaluating RF exposure. SAR tells you how much RF power your body absorbs per kilogram. If SAR is 0.08 W/kg (the limit for general public), that means your body is absorbing 0.08 watts per kilogram of body weight. Higher SAR means more absorption and higher risk. MPE limits are based on safe SAR values.
错误选项分析
Option A: Incorrect. SAR doesn't measure signal attenuation ratio. SAR is about energy absorption by the body, not signal attenuation. Option B: Incorrect. SAR doesn't measure signal amplification rating. SAR measures how much RF energy the body absorbs, not signal amplification. Option D: Incorrect. SAR doesn't measure RF energy reflection from terrain. SAR is about energy absorption by the body, not terrain reflection.
知识点
SAR, Specific Absorption Rate, RF absorption, RF exposure
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.