HB3YAQLucerne
Power ratio in dB
Compare two powers and interpret their ratio.
HB3YAQ · Ajdin HadzicLearning to take awayhttps://hb3yaq.ch/en/tools/decibels
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Formula & context
G = 10 log₁₀(P₂ / P₁)
dB describes a ratio. Positive values mean more power than the reference, negative values less. Gains and losses of successive stages can be added in dB.
A worked example
5 to 10 W is +3.0103 dB. 10 to 5 W is −3.0103 dB.
Assumptions & limits
Use 20 log for voltage ratios only with equal resistance. dB is not absolute power; that requires a reference such as dBm.
dB, dBm and powerUnderstand the reasoning →From reading to experimenting
Power ratio in dB
5 to 10 W is +3.0103 dB. 10 to 5 W is −3.0103 dB.
Open example with starting values →Reference power P₁: 5 W · Compared power P₂: 10 WBack to the learning article →Then change exactly one value. Compare the result and use the formula to explain why it changes. The model limits below the calculator also apply here.