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GATE 2026 EC – Question 52

Electromagnetics · Transmission Lines · 2 marks · Multiple choice

A complex load (in Ω) is represented as $\Gamma_L=0.5\angle30^\circ$ on the Smith chart. A co-axial cable with a characteristic impedance of 50 Ω is connected to the load. The new input impedance of the load now moves to a diametrically opposite point on the same Γ circle on the Smith chart. Which option is the nearest input impedance of the cable connected load (in Ω)?

  1. $20.7-j5.1$
  2. $17.7-j11.8$
  3. $97.5-j65.0$
  4. $97.5+j65.0$

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Correct answer: (B) $17.7-j11.8$

Explanation

The diametrically opposite point has $\Gamma=0.5\angle210^\circ=-0.433-j0.25$. Then $Z=50(1+\Gamma)/(1-\Gamma)=50(0.567-j0.25)/(1.433+j0.25)\approx17.7-j11.8\ \Omega$.