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A loss-less transmission line of length l is open-circuited and has characteristic impedance Z0. The input impedance is 

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  1. + j Z0 tan βl
  2. - j Z0 tan βl
  3. - j Z0 cot βl
  4. + j Z0 cot βl

Answer (Detailed Solution Below)

Option 3 : - j Z0 cot βl
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Detailed Solution

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Concept:

The input impedance in a transmission line is given by:

'l' = Length of the line from the Load

β = 2π/λ = Wavenumber

Z0 = Characteristic Impedance of the Transmission Line

ZL = Load Impedance

Analysis:

For open-circuited load, ZL ≈ ∞, the input impedance will be:

Zin = -Z0 cot βl

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