S11 for marker 1 says -47.661 dB
Two Questions
1st ….. What is | S11 | ^ 2
2nd
Is this accurate ?
g = 20 log_10(-47.661) dB
Electronic – S-Parameters math confusion
RFs-parametersspectrum analyzer
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Best Answer
\$\left|S_{11}\right|^2\$ is a power ratio. -47 dB means a power ratio of roughly 2/100,000 or 0.00002 (because -50 dB would be 1/100,000 and +3 dB is about 2x)
You could also get this result by simply changing your network analyzer to display a linear scale.
Since you haven't defined \$g\$, it's not possible to answer this.
But it would be very unusual to take the log of a decibel value. You get decibels by taking the log of a power ratio. Taking the log again doesn't generally give a meaningful result.
If you want to convert a decibel value \$X\$ back to a power ratio, you'd use $$\frac{P_2}{P_1} = 10^{X/10}.$$
If you want to convert a decibel value \$X\$ back to a voltage ratio (assuming equal reference impedances for both signals), you'd use $$\frac{V_2}{V_1} = 10^{X/20}.$$