🔍 Key Concepts

• Decibels (dB) as a measure of power ratio, not absolute power • How a negative dB value relates to a fraction of the original power • Converting a dB value to a power ratio using 10·log₁₀(P₂/P₁)

💭 Think About

• How do you convert -30 dB into a numerical power ratio (like 1/10, 1/100, 1/1000, etc.)? • Once you know the power ratio, how does the 100 mW measured at the coupler relate to the actual line power? Is it larger or smaller than 100 mW? • Which answer choice matches the line power when you scale the 100 mW by the ratio you found from -30 dB?

✅ Before You Answer

• Confirm that for power, dB is calculated with 10·log₁₀(Pmeasured/Preference), not 20·log₁₀ (that’s for voltage). • Verify the correct interpretation of -30 dB (is it 1/30, 1/300, 1/1000, or something else?). • After finding the ratio, be sure to convert milliwatts (mW) to watts (W) correctly before comparing with the answer choices.