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GATE 2020 EC – Question 56

Networks, Signals and Systems · Two-Port Networks and Wye-Delta Transformation · 2 marks · Numerical answer

For a 2-port network consisting of an ideal lossless transformer, the parameter $S_{21}$ (rounded off to two decimal places) for a reference impedance of $10\ \Omega$, is ________.

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Correct answer: 0.79 to 0.81

Explanation

For an ideal transformer with turns ratio $n=2$ and the same reference impedance at both ports, $S_{21}=\frac{2n}{n^2+1}=\frac{2\times2}{4+1}=0.8$.