Q. Assertion (A): TWT uses a focussing mechanism to prevent the electron beam from spreading.

Reason (R): In a TWT the electron beam has to travel a much longer distance than in klystron.

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Q. In a TWT the amplitude of resultant wave travelling down the helix

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Q. Which of the following is not a travelling wave?

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Q. Both Impatt and Trapatt devices use avalanche effect

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Q. The directive gain of a transmitting antenna is

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Q. A duplexer is used to

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Q. A branched duplexer requires

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Q. In a backward wave oscillator the wave

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Q. A transmission line has Z0 = 300 Ω and ZL = (300 - j300) ohm. The transmission coefficient is

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Q. In a reflex klystron oscillator, repeller electrode is at

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Q. A quarter wave line short circuited at load end behaves as

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Q. A (75 - J50) ohm load is connected to a coaxial of Z0 = 75 ohm at 10 GHz. The best method of matching is to connect

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Q. The width of a radio beam from a 1 m diameter parabolic antenna at 1 GHz is about

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Q. To couple a coaxial line to a parallel wire line it is best to use

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Q. Assertion (A): A quarter wave transformer is used to match a resistive load to a transmission line.

Reason (R): A quarter wave transformer is a transmission line of quarter wave length.

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Q. Assertion (A): Magnetron is generally used in n mode.

Reason (R): Frequency for π mode can be easily separated from adjacent modes.

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Q. A balun should have

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Q. Assertion (A): The velocity factor of a line is the ratio of wave velocity on the line to speed of light.

Reason (R): If the conductors of a line are immersed in a non magnetic insulating liquid, the wave velocity increases.

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Q. The directivity in a receiving antenna

1. increases the intercept area in forward direction
2. reduces the noise picked up from other sources
3. provides a means of discriminating against undesired signals originating in directions other than in which the desired transmitter lies.

Which of the above statements are correct?

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Q. Assertion (A): PIN diode can be used as attenuator and limiter.

Reason (R): PIN diode has a thin intrinsic layer.

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