GATE ECE Transmission lines PYQs & Answers

Questions 1–10 of 22. Imported answers require independent review unless marked reviewed.

Consider the Friis’ transmission equation

, where

and

are the received and the transmitted powers, respectively.

and

are the gain of transmitting and receiving antennas, respectively,

is the distance between the transmitting and receiving antennas, and

is the wavelength in free space.

Given:

and

Choose the distance (D), in km, from the following options at which the received power,

Your answerChoose one option.

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The cutoff frequency (in GHz) for the dominant TE₁₀ mode of an air-filled rectangular waveguide of inner dimension 0.28 inch × 0.14 inch is __. (rounded off to two decimal places).

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For a lossless passive two-port network, |S₁₁| and |S₂₁| intersect at −3 dB. For a lossy passive two-port network, |S₁₁| and |S₂₁| intersect at −4 dB. The percentage of power dissipated in the lossy network at the intersection frequency is __. (rounded off to two decimal places)

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A complex load (in Ω) is represented as

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)?

Your answerChoose one option.

20.7 − j5.1

17.7 − j11.8

97.5 − j65.0

97.5 + j65.0

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A 50

lossless transmission line is terminated with a load

If the average incident power on the line is 10 mW, then the average power delivered to the load (in mW, rounded off to one decimal place) is __________.

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Consider a lossless transmission line terminated with a short circuit as shown in the figure below. As one moves towards the generator from the load, the normalized impedances

, and

(indicated in the figure) are ______.

Diagram for Electronics and Communication Engineering question 15

Your answerChoose one option.

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A lossless transmission line with characteristic impedance

is terminated with an unknown load. The magnitude of the reflection co-efficient is

. As one moves towards the generator from the load, the maximum value of the input impedance magnitude looking towards the load (in

) is ______.

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The S-parameters of a two port network is given as

with reference to

. Two lossless transmission line sections of electrical lengths

and

are added to the input and output ports for measurement purposes, respectively. The S-parameters

of the resultant two port network is

Diagram for Electronics and Communication Engineering question 51

Your answerChoose one option.

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The standing wave ratio on a 50

lossless transmission line terminated in an unknown load impedance is found to be 2.0. The distance between successive voltage minima is 30 cm and the first minimum is located at 10 cm from the load.

can be replaced by an equivalent length

and terminating resistance

of the same line. The value of

and

, respectively, are