| 1. | To avoid difficulties with strapping at high frequencies, what type of cavity structure is used in the magnetron ? | |
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Slot
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Hole and slot
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Rising sun
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Vane
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Report Question| 2. | Gallium arsenide is preferred to silicon for use in Gunn diode because it has ? | |
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lower noise at high frequencies
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suitable empty energy band which silicon does not have
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high ion mobility
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better frequency stability
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| 3. | A diode with no junction that is widely used with a cavity resonator to form a microwave oscillator is a/an ? | |
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IMPATT diode
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GUNN diode
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TRAPATT diode
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TUNNEL diode
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| 4. | Which of the following uses transferred electron effect' for production of microwaves ? | |
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Germanium
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Silicon
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Gallium arsenide
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Metal-semiconductor junction
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| 5. | In the Gunn diode, out of its various modes of operation, one mode is independent of domain transit time and hence can be used at high frequency and for very high output powers. Which is this mode ? | |
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Transit time mode
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Limited space charge accumulation mode
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Quenched domain mode
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Delay domain mode
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| 6. | The main purpose of inserting a microwave isolator in a microwave circuit is for ? | |
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maintaining frequency stability of the source
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offering minimum forward impedance
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maintaining amplitude stability of output power
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offering maximum power output from the source
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| 7. | A calorimetric measurement for average power of a signal gave a value of 400 W. The value was interpreted for peak power as 0.5 MW. Then the duty cycle of the signal is ? | |
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40 per cent
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0.08 per cent
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80 per cent
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8 per cent
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| 8. | A 50 ohm coaxial line is connected to a 72 ohm load through a 60 ohm coaxial section of length 7.5 mm. What is the input VSWR on the line if it is fed by a 20 GHz source ? | |
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1.0
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1.25
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1.44
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1.33
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| 9. | A slotted line is used for the measurement of VSWR. The slot is cut at the centre, because ? | |
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the field inside the waveguide will not be perturbed
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to get a good impedance matching
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maximum field will be induced to the penetrating probe
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no field will be coupled to the probe
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| 10. | The underlying principle of working of a cavity wavemeter, tuned to measure frequency of microwaves in a system, is ? | |
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resonance of a cavity with incoming microwave energy
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selective absorption of microwave energy in solids
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selective diffraction of microwaves around a cavity
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selective scattering of microwave energy by a cavity
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